INTRODUCTION — The lymphatic drainage areas of the breast (axillary, internal mammary, and supraclavicular nodal groups) are the nodes most likely to be involved in patients with metastatic breast cancer.
The risk of breast cancer spreading to regional lymph nodes, the preoperative assessment of the axilla, and the indications for axillary dissection and axillary radiation are reviewed in this topic.
The techniques for performing a sentinel lymph node biopsy (SLNB), an axillary lymph node dissection (ALND), axillary radiation, and the management of the axilla in the clinical setting of neoadjuvant therapy are discussed elsewhere.
●(See "Overview of sentinel lymph node biopsy in breast cancer".)
●(See "Sentinel lymph node biopsy in breast cancer: Techniques".)
●(See "Technique of axillary lymph node dissection".)
REGIONAL LYMPH NODES RELEVANT TO BREAST CANCER — The axillary lymph nodes receive the majority of the lymphatic drainage from all quadrants of the breast; the remainder drains to the internal mammary, infraclavicular, and/or supraclavicular lymph nodes.
Axillary lymph nodes — The axillary lymph nodes (ALNs) receive 85 percent of the lymphatic drainage from all quadrants of the breast.
The likelihood of ALN involvement is related to tumor size, location, and certain histologic features (eg, grade, lymphatic invasion, receptor status) [1,2].
●Tumor size – In general, larger primary tumors are associated with a higher likelihood of ALN involvement (although this can vary with tumor subtype) [3-5]. As an example, in a series of 6800 women diagnosed with invasive breast cancer after screening mammography, the incidence rate of ALN involvement increased with tumor size (table 1) [6].
However, ALN metastases are relatively common even with invasive breast cancers ≤1 cm in size [1,2,7-10]. In a report of 919 women who underwent ALN dissection, ALN metastases were detected in 16 and 19 percent of those with T1a (tumor size 0.1 to 0.5 cm in greatest dimension) and T1b tumors (tumor size 0.5 to 1.0 cm), respectively [10]. (See "Tumor, node, metastasis (TNM) staging classification for breast cancer".)
●Tumor location – ALNs are more commonly involved with tumors in the lateral rather than the medial portion of the breast [3,11,12]. As an example, in a study of 1671 early-stage breast cancers, the odds ratio of a lateral tumor having ALN metastasis was 1.33 (95% CI 0.95-1.87) relative to a medial tumor [13]. The most likely explanation for this difference is the preferential drainage of some medial tumors to the internal mammary nodes [14]. (See 'Internal mammary lymph nodes' below.)
●Histologic features – Grade 1 tumors have a significantly lower rate of ALN metastases compared with grade 2 or 3 tumors [9]. As an example, in data derived from the Surveillance, Epidemiology, and End Results (SEER) database, the incidence of ALN involvement in patients with grade 1 and grade 3 tumors of similar size was 3.4 and 21 percent, respectively [9].
Tumors that are associated with a less than 5 percent risk of ALN metastases include those with a single focus of microinvasion [15,16], <5 mm grade 1 tumors without lymphatic invasion, and pure mucinous or pure tubular carcinomas <1 cm [17,18]. (See "Pathology of breast cancer".)
Correcting for size, some tumor subtypes (eg, HER2+, triple-negative) have higher node positivity rates than others (eg, luminal).
●Detection method of primary tumor – Across all size categories, patients whose invasive tumors are detected by screening mammography are more likely to have pathologically negative lymph nodes than those with clinically detected tumors [6].
●Management – The preoperative evaluation and management of metastatic axillary lymph nodes in breast cancer is discussed in detail below. (See 'Axillary evaluation' below and 'Axillary management' below.)
Internal mammary lymph nodes
●Presentation – Like the ALNs, the internal mammary nodes (IMNs) receive lymph drainage from all quadrants of the breast [19]. However, medial tumors have a significantly higher rate of IMN metastases [20]. Although the IMN chain extends from the fifth intercostal space to the retroclavicular region, nodes in the upper three interspaces are most likely to contain metastases [21-23].
Isolated IMN metastases are infrequent; more often, ALNs are involved as well [14,20,24]. In a report of over 7000 cases in which the IMNs and ALNs were examined, IMN metastases were detected in 22 percent, but fewer than 5 percent of the node-positive patients had IMN-only disease [14]. Isolated IMN involvement was more frequent for medial than lateral tumors (7.6 versus 2.9 percent).
●Imaging – There are no convincing data that routine imaging of IMNs is needed in clinically node-negative breast cancer patients. They may be imaged as part of staging positron emission tomography (PET) or chest computed tomography (CT) scans, which patients undergo if there is concern for metastatic disease. The results may change the patient's nodal stage and impact surgical and radiation treatments. (See "Clinical features, diagnosis, and staging of newly diagnosed breast cancer", section on 'Role of imaging'.)
●Management – The management of IMNs is controversial.
•Sentinel lymph node biopsy – Dissection of the IMNs with SLNB is considered investigational [20,25-29]. Using standard technique, IMNs are only visualized in 20 percent of patients during SLNB. An IMN is rarely positive if an axillary sentinel lymph node is removed that is negative. Given that the IMN status rarely changes management, and that the nodes in the axilla usually reflect the IMN status, very few surgeons would perform SLNB of an IMN or even try to identify them preoperatively with lymphoscintigraphy. Potential complications of IMN SLNB include pleural effusion and injury to the internal mammary artery [30]. (See "Overview of sentinel lymph node biopsy in breast cancer", section on 'Internal mammary nodes'.)
•Radical dissection – Following four early (1960s) randomized trials showing no survival benefit from extended mastectomy (which included IMN dissection) compared with radical or modified radical mastectomy (even in the absence of chemotherapy), routine dissection of IMN was abandoned [31-34]. Furthermore, the widespread use of adjuvant systemic therapy for women with both node-positive and node-negative breast cancer has diminished the importance of the IMNs in clinical care.
•Radiation therapy – However, for women receiving adjuvant regional radiation therapy (RT), either after breast-conserving surgery or with postmastectomy RT (PMRT), RT of the IMNs is generally included. Indications for regional RT are discussed elsewhere. (See "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer", section on 'Indications for regional nodal irradiation' and "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer", section on 'Patients treated with mastectomy'.)
However, an individualized approach is necessary that takes into account the patient's risk for IMN involvement, the anatomy, and the ability to exclude critical structures (eg, the heart) from the treatment field. (See "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer", section on 'RT of internal mammary nodes'.)
Supraclavicular lymph nodes
●Presentation – Supraclavicular nodal metastases are usually associated with extensive ALN involvement and are rare in its absence. As an example, in a series of 274 women undergoing routine supraclavicular dissection, supraclavicular nodal metastases were found in 18 and 0.7 percent of those with and without ALN metastases, respectively [35].
●Management – Supraclavicular nodal metastases represent locally advanced disease. Nonetheless, curative treatment is possible with aggressive multimodality treatment, typically consisting of neoadjuvant systemic therapy, surgery, possible adjuvant systemic therapy, and radiation [36,37].
AXILLARY EVALUATION — The axilla of patients with breast cancer can be assessed with physical examination, axillary ultrasound, and/or percutaneous needle biopsy (core needle biopsy [CNB] or fine needle aspiration [FNA]). The optimal pathway depends on the tumor size and pathologic features, including its receptor status, as these factors influence whether neoadjuvant systemic treatment will be offered.
Physical examination — All patients undergo physical examination of the axilla. However, it is neither sensitive nor reliable in ascertaining the status of the axillary lymph nodes (ALNs) because metastatic lymph nodes are often not palpable, and reactive lymph nodes may be mistaken for metastases. The positive predictive value of clinical palpation (ie, likelihood of finding axillary metastases in a patient with suspicious findings on physical examination) ranges from 61 to 84 percent, while the negative predictive value (ie, the likelihood that axillary nodal metastases are absent in a patient with no suspicious findings on physical examination) is only 50 to 60 percent [38-40]. In the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-32 sentinel node trial, in patients with negative axillary nodes by clinical examination, the node-positive rate was 26 percent [41]. However, the risk of individual patients is influenced by factors such as tumor size (table 1). (See "Clinical manifestations, differential diagnosis, and clinical evaluation of a palpable breast mass", section on 'Palpation'.)
Axillary ultrasound — Axillary ultrasound is an effective screening method for detecting nodal metastasis in patients with invasive breast cancer [42]. Sonographic suggestions of metastatic disease include cortical thickening >3 mm, loss of fatty hilum, and irregular margins (image 1 and image 2) [43]. However, the efficacy of ultrasound-guided biopsy can vary between centers because the accuracy of ultrasound examination is operator dependent [44]. (See "Diagnostic evaluation of suspected breast cancer", section on 'Axillary ultrasound'.)
The use of axillary ultrasound in patients with newly diagnosed invasive breast cancer varies between centers [45]. Some experts routinely perform axillary ultrasound in all patients with a newly diagnosed invasive breast cancer, while others only perform ultrasound for clinically positive (palpable) nodes or when neoadjuvant chemotherapy is planned.
For patients who are not planning to undergo neoadjuvant chemotherapy, the benefit of preoperative axillary ultrasound is debated:
●Proponents argue that ultrasound staging can identify patients with a high axillary disease burden (≥3 metastatic nodes, extranodal extension, or level III nodes), who may go straight to ALND [46-48]. In a retrospective study of patients with non-metastatic T1 or T2 breast cancer who had only one metastatic node on preoperative ultrasound, preoperative ultrasound had a sensitivity and negative predictive value of 92 percent and false negative rate of 8 percent; the performance of ultrasound was comparable to that of sentinel lymph node biopsy (SLNB) [49].
●Opponents argue that early breast cancer patients are not likely to have a large number of involved axillary nodes. They further argue that ultrasound cannot differentiate between one or two positive nodes from three or more positive nodes and thus does not have sufficient negative predictive value to bypass SLNB and does not add more information to SLNB [50-53].
●Use of axillary ultrasound as a substitute for SLNB in selected patients is being evaluated. (See 'Can ultrasound identify patients who can omit sentinel node biopsy?' below.)
For patients who are planning to undergo neoadjuvant chemotherapy, the benefit of preoperative axillary ultrasound is that it permits targeted axillary dissection by identifying, guiding biopsy of, and marking any positive node(s) [48] (see 'Comparison of modalities' below). In the Z1071 trial, targeted axillary dissection reduced the false negative rate of SLNB from 12.6 to 6.8 percent in patients with positive axillary nodes undergoing neoadjuvant treatment [54].
Percutaneous needle biopsy — Abnormal lymph nodes identified on axillary ultrasound should undergo needle biopsy for pathologic analysis [42,45,55-60]. Such biopsies, either CNB or FNA, can be performed percutaneously under ultrasound guidance. However, until further data become available, needle biopsy of an abnormal axillary lymph node(s) does not obviate surgical evaluation of the axilla, and SLNB is still required in most patients with breast cancer. (See "Breast biopsy".)
AXILLARY MANAGEMENT — The decision to give neoadjuvant chemotherapy, endocrine therapy, and immunotherapy depends on the hormone receptor and HER2 status and stage of the cancer. The selection of patients for neoadjuvant therapy is discussed elsewhere. (See "General principles of neoadjuvant management of breast cancer", section on 'Patient selection'.)
Our approach to axillary management depends, in part, on whether a patient received neoadjuvant treatment. (See 'Patients who do not undergo neoadjuvant therapy' below and 'Patients who undergo neoadjuvant therapy' below.)
Rationale for axillary management — Axillary treatment improves regional disease control; however, with improved systemic treatment, there is no clear evidence of an improvement in overall survival.
In the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-04 trial, clinically node-negative patients were randomly assigned to total mastectomy and axillary lymph node dissection (ALND), total mastectomy with regional radiation therapy (RT), or total mastectomy only with delayed ALND at the time of recurrence [61]. Although the 10-year survival was similar in the three groups, the axillary failure rate was significantly higher in women treated with mastectomy alone (without ALND or regional RT; 18 percent) compared with those undergoing regional RT or initial ALND (3.1 and 1.4 percent, respectively). The rate of axillary failure was probably higher than 18 percent in those undergoing delayed ALND because inoperable axillary recurrences and operable axillary recurrences that occurred simultaneously with or after distant metastases were excluded. It should be noted, however, that the time period for this study was 1971 to 1974, when the use of mammographic screening was neither widespread nor as sophisticated as it is presently, and adjuvant systemic therapy was less refined. Additionally, the mean tumor size in this study was generally larger than currently identified.
Since the likelihood of subclinical axillary metastases increases with increasing tumor size, we would anticipate that axillary failure rates without dissection or radiation today would be significantly lower than 18 percent, especially in light of contemporary adjuvant systemic treatment regimens. Indeed, the axillary relapse rate in the Z0011 trial was 0.5 percent with ALND and 1 percent with SLNB alone [62].
Comparison of modalities — There are two modalities of axillary treatment for breast cancer, surgery (sentinel lymph node biopsy [SLNB], targeted axillary dissection [TAD], or ALND) and radiation (regional radiotherapy). Given randomized trial data showing that many women with limited or no sentinel lymph node involvement can safely omit ALND and be treated with radiation only, this has become the standard approach for women who have early breast cancer and clinically negative axillary nodes, as discussed elsewhere. (See "Overview of sentinel lymph node biopsy in breast cancer", section on 'Management after SLNB'.)
●Sentinel lymph node biopsy – In patients with clinically node-negative early breast cancer, SLNB identifies patients with limited or no axillary lymph node (ALN) involvement who may therefore be able to avoid more extensive surgery. The decision about proceeding with ALND is based on the results of SLNB, primary tumor size, and other factors. (See "Overview of sentinel lymph node biopsy in breast cancer".)
●Targeted axillary dissection – TAD is an axillary staging technique that removes any biopsy-proven positive axillary nodes (targeted lymph node biopsy [TLNB]), which are marked with a clip or tattoo prior to neoadjuvant chemotherapy, in addition to SLNB. TAD is an adaptation of axillary sampling that targets removal of positive nodes while minimizing morbidity. In a meta-analysis of over 3000 patients, the pooled success rate of identifying and retrieving a marked node was 90.0 percent (95% CI 85.1-95.1). Compared with ALND in 13 studies, TAD was associated with a false negative rate of 5.18 percent (95% CI 3.41-7.54) [63]. In a prospective registry study of 548 patients with node-positive breast cancer, the clipped node was intraoperatively resected in 78 percent, TAD was successful in 87 percent, the sentinel node and targeted node were identical in 65 percent. The false negative rate was 7.2 percent for TLNB and 4.3 percent for TAD when compared with ALND [64].
●Axillary lymph node dissection – Histologic examination of removed lymph nodes from an ALND is the most accurate historical method for assessing local spread of disease to regional nodes. The potential utility of ALND for patients with clinically positive axillary nodes includes its impact on disease control (ie, axillary recurrence), its prognostic value, and its role in treatment selection. However, the anatomic disruption caused by ALND may result in lymphedema, nerve injury/pain, and shoulder dysfunction (reduced strength and range of motion), which compromise functionality and quality of life compared with SLNB [65]. As such, although ALND was once a routine component of the staging and management of breast cancer [66], SLNB is now accepted as the standard initial approach for women with early breast cancer who meet the Z-0011 criteria [67]. (See "Technique of axillary lymph node dissection".)
Both axillary dissection and radiation therapy to the axilla increase the risk of long-term ipsilateral arm lymphedema, and so use of both together is often avoided, except in very-high-risk circumstances. (See "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer", section on 'Involved lymph nodes'.)
●Regional radiotherapy – Standard whole breast radiation therapy (WBRT), offered to women after breast-conserving surgery or postmastectomy radiation therapy (PMRT), includes two tangential radiation fields to the breast or chest wall, which generally covers the low ipsilateral axillary nodes. Full regional RT is defined as the use of an additional third radiation field and in some cases a fourth field to ensure treatment of the supraclavicular, infraclavicular, and upper ALNs. (See "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer".)
Several randomized trials have directly compared locoregional failure rates and survival in women treated with ALND or regional RT in women with early-stage breast cancer [68-70]. All have shown low rates of axillary failure after either ALND or regional RT and similar long-term survival, and as such, many women are able to avoid ALND, with incorporation of regional RT. The selection of women who may be able to avoid ALND is according to the results of SLNB. (See 'Patients who do not undergo neoadjuvant therapy' below and 'Patients who undergo neoadjuvant therapy' below.)
Two trials comparing ALND and RT are as follows:
●Reported in 2014, the After Mapping of the Axilla: Radiotherapy or Surgery (AMAROS) trial was a multi-institutional trial [71,72]. The trial included 4806 patients with T1 or T2 primary, unifocal, invasive breast cancer without palpable axillary lymphadenopathy. Of the 1425 patients who were found to have positive sentinel lymph nodes by SLNB, 744 were randomly assigned to receive ALND and 681 to receive axillary radiotherapy. Ninety-five percent of patients in both groups had one or two positive sentinel nodes. The 10-year axillary recurrence rate was 0.93 percent (95% CI 0.18-1.68) in the ALND group and 1.82 percent (95% CI 0.74-2.94) in the axillary radiation group. There were no statistically significant differences in survival between treatment groups. Lymphedema was noted significantly more often after ALND than after axillary radiation at one, three, and five years (25 versus 12 percent). The 10-year cumulative incidence of second primary cancers was 12.1 percent (95% CI, 9.6 to 14.9) after axillary radiation and 8.3 percent (95% CI, 6.3 to 10.7) after ALND.
The 10 year follow-up results of the AMAROS trial have been reported in abstract form [73]. After 10 years, the axillary recurrence rate remained low and comparable between the ALND group (7/744 patients; 0.93 percent) and the axillary radiotherapy group (11/681 patients; 1.82 percent). Distant metastasis-free survival and overall survival rates were similar. While this trial did find more second primary cancers developed in patients treated with axillary radiotherapy (11.0 versus 7.7 percent, p = 0.035), some of these cancers were contralateral breast cancers. It is unclear how much of this was due to the axillary radiation versus chance alone.
●In the OTOASOR trial, 474 patients with cT ≤3 cm, cN0, and pN1 (sentinel node) breast cancer were randomly assigned to completion ALND versus axillary RT. There was no statistically significant difference in axillary recurrence or overall survival between the two groups of patients at 40 months (axillary recurrence 0.82 percent ALND, 1.3 percent RT) [74] and at 97 months (axillary recurrence 2 percent ALND, 1.7 percent RT; overall survival 77.9 [ALND] versus 84.8 percent [RT]; disease-free survival 72.1 [ALND] versus 77.4 percent [RT]) [75].
Patients who do not undergo neoadjuvant therapy — Most patients without known axillary metastases undergo SLNB, with choices regarding ALND or regional nodal irradiation (or both) depending on the results of the SLNB. (See 'No known axillary nodal metastasis' below.)
The approach to patients with known axillary metastases is described below. (See 'Known axillary nodal metastasis prior to surgery' below.)
No known axillary nodal metastasis — Preoperative axillary evaluation is discussed above. (See 'Axillary evaluation' above.)
Patients who have no axillary nodal metastasis found on preoperative axillary evaluation should proceed directly to SLNB at the time of primary breast surgery. For such patients, SLNB is the standard method for axillary staging and can reliably distinguish between patients requiring ALND and those for whom radiation alone or observation is sufficient [45,76-78].
Further management of the axilla depends on the outcomes of the SLNB (algorithm 1):
No positive sentinel node — Patients who do not have nodal metastases on SLNB do not require ALND. (See "Overview of sentinel lymph node biopsy in breast cancer", section on 'No sentinel node metastasis'.)
Randomized trials including patients with high-risk node-negative disease have suggested improvements in breast-cancer-free survival with regional RT [79,80]; as such, we offer regional RT in addition to WBRT to women with high-risk, node-negative disease, although this practice varies between centers. High-risk disease includes T3 or T4 disease as well as those with T2 tumors who have undergone limited axillary dissection (<10 lymph nodes) and also have other risk factors, including high-grade histology, estrogen receptor (ER)-negative tumors, or lymphovascular invasion [80]. (See "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer", section on 'High-risk features of the primary tumor'.)
For the majority of patients who do not have high-risk features of the primary tumor, regional RT is not required.
One or two positive sentinel nodes
●Breast-conserving surgery – For most patients who have one or two sentinel lymph nodes positive for metastases and who will receive breast-conserving surgery with WBRT, we do not perform completion ALND.
For many of these patients, we offer the addition of regional RT to WBRT. However, this practice also varies between centers; some centers use only WBRT, as this was the strategy performed in the Z-0011 trial; other centers raise the breast tangents to radiate more of the axilla without adding additional fields. Available data are discussed in detail elsewhere. (See "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer", section on 'Involved lymph nodes'.)
An exception is that for women with micrometastatic disease to one to two lymph nodes, in general, we do not add regional RT in the absence of other high-risk features. However, regional RT may be added in patients with micrometastatic lymph node disease if other high-risk features are present. Again, this is not a uniform practice across all centers. (See "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer", section on 'Exception for micrometastatic nodal disease'.)
●Mastectomy – For patients who have one or two sentinel lymph nodes positive for metastases, we do not perform complete ALND. (See "Overview of sentinel lymph node biopsy in breast cancer", section on 'One or two sentinel node metastases' and "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer".)
We offer postmastectomy radiation therapy (PMRT) for such patients. Although there is some debate, we generally proceed with PMRT for these patients to maximize the opportunity to reduce the risk of recurrence and potentially improve disease-specific survival, based on data from randomized trials [81,82]. However, given that the absolute magnitude of benefit derived depends on the baseline risk of locoregional failure, an individualized approach that takes into account patient preference and high-risk features is necessary. Those with micrometastatic diseases only do not require PMRT unless there are high-risk features.
Patients who desire immediate reconstruction after mastectomy may not be optimal candidates for PMRT, because of cosmetic concerns. Some centers offer such patients PMRT with a tissue expander to circumvent contractions and other wound issues that can occur with radiation.
More positive lymph nodes — Our practice with regard to number of positive sentinel nodes is as follows: we perform completion ALND in patients with three or more positive sentinel nodes, regardless of whether they had mastectomy or breast-conserving surgery. The need for regional RT would be discussed with regard to risk factors. For patients with four or more nodes, we typically administer comprehensive regional RT; patients with one to three nodes with other high-risk features (large primary tumor, extensive lymphovascular invasion, etc) typically also receive regional RT. Regional RT is more controversial for those with small tumors (T1 or T2) with one to three nodes without extracapsular disease or extensive lymphovascular invasion and is discussed in more detail elsewhere, both for those who undergo breast-conserving therapy (see "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer", section on 'Involved lymph nodes') as well as for those who undergo mastectomy. (See "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer", section on 'Involved lymph nodes'.)
Regional RT, when performed after breast-conserving therapy, is performed in addition to WBRT and as a part of PMRT (in addition to chest wall radiation) after mastectomy. (See "Overview of sentinel lymph node biopsy in breast cancer", section on 'Three or more sentinel node metastases'.)
Known axillary nodal metastasis prior to surgery — Patients with clinically bulky, biopsy-confirmed node-positive disease (eg, via needle biopsy) prior to breast surgery who do not undergo neoadjuvant treatment are managed with ALND at the time of the primary breast procedure, given high recurrence rates in this high-risk population [83]. Such patients are also often recommended for adjuvant regional RT.
Patients with node-positive disease based on biopsy alone (ie, non-clinically bulky) can undergo SLNB, with further management dictated by the result of SLNB [84]. (See 'Patients who do not undergo neoadjuvant therapy' above.)
The use of RT in such patients is discussed elsewhere. (See "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer", section on 'Involved lymph nodes'.)
Omitting axillary surgery
Select older patients with small hormone receptor-positive tumors — Select older patients with small (≤3 cm) ER-positive, HER-2/neu-negative tumors who will receive adjuvant endocrine therapy and who are clinically node negative may be managed without any axillary surgery [85-87]. That is because knowledge of the status of the axillary lymph nodes may not influence treatment recommendations or outcomes in these patients [88]. The exact criteria for omitting axillary surgery may vary by guidelines [89]. Additionally, chronologic age may differ from "biological age," and some older women with good baseline health may have a higher likelihood of benefit from treatments such as RT or chemotherapy than a younger patient with significant comorbidities. Other risk factors (eg, tumor grade, intensity of ER expression, etc) also need to be considered. (See "Overview of the approach to early breast cancer in older women", section on 'Management of the axilla'.)
Most cases of ductal carcinoma in situ — By definition, in situ cancer does not metastasize. However, lymph node metastases are found in 0.2 and 0.7 percent of ductal carcinoma in situ (DCIS) due to the occasional undetected presence of an invasive cancer component in the surgical specimen [90,91]. Hence, axillary staging in the form of SLNB is only required for patients undergoing mastectomy. Some opt to do SLNB in cases of DCIS with suspicious features suggestive of underlying invasive cancer; however, for patients undergoing lumpectomy, an SLNB can always be performed after the upstaged diagnosis to invasive disease is found. (See "Overview of sentinel lymph node biopsy in breast cancer", section on 'DCIS with planned mastectomy or suspicious features'.)
Can ultrasound identify patients who can omit sentinel node biopsy? — Trials are evaluating whether selected patients with low-risk cancers can safely omit sentinel node biopsy. However, although the choice of adjuvant therapy is increasingly decided by biologic parameters, axillary nodal information is still used to determine the choice and duration of adjuvant chemotherapy and endocrine therapy, as well as regional radiation field [92]. This is especially true for the younger population. As such, we continue to use sentinel biopsy to evaluate a clinically negative axilla , except for cases outlined above (see 'Select older patients with small hormone receptor-positive tumors' above and 'Most cases of ductal carcinoma in situ' above).
The Sentinel Node Versus Observation After Axillary Ultrasound (SOUND) trial compared SLNB versus axillary observation in 1463 women with stage I (<2 cm) breast cancer and negative axillary ultrasound [93]. Fourteen percent of patients who underwent SLNB had at least one metastatic sentinel node (5.1 percent micrometastasis, 8.6 percent macrometastasis); 0.6 percent had >4 metastatic sentinel nodes. At five years, only 0.4 percent of patients in both groups developed axillary recurrence. The rates for distant metastasis, overall survival, and disease-free survival were also similar. Omission of surgical axillary staging did not impact the selection of adjuvant treatment, although the study population included largely patients with low-risk cancers (93 percent with ER positive, HER2 negative cancer).
The results of additional ongoing trials, such as the Intergroup-Sentinel-Mamma (INSEMA) [94], Clinically Node Negative Breast Cancer Patients Undergoing Breast Conserving Therapy: Sentinel Lymph Node Procedure Versus Follow-up (BOOG 2013-08) [94], and No Axillary Surgical Treatment for Lymph Node-Negative Patients after Ultrasonography (NAUTILUS) [95], may further clarify the requirement for axillary ultrasound staging in breast cancer and may further de-escalate axillary surgical management for breast cancer when axillary ultrasound is negative.
Patients who undergo neoadjuvant therapy — For patients undergoing neoadjuvant therapy, after its completion, the axilla should be reevaluated with clinical examination and possibly a repeat ultrasound according to some authors. The information gathered by the axillary assessments prior to and after neoadjuvant therapy should inform the choice of axillary surgery (SLNB versus ALND). Unless there is clear evidence of residual nodal disease, most experts would favor an SLNB given the higher morbidity of ALND; nodes that appear suspicious radiographically may be negative on pathology evaluation. (See "General principles of neoadjuvant management of breast cancer", section on 'Management of the axilla'.)
Although it is our practice to perform SLNB after neoadjuvant chemotherapy (NACT), some institutions perform SLNB prior to NACT. The decision regarding when to perform SLNB in patients receiving NACT is discussed elsewhere. (See "General principles of neoadjuvant management of breast cancer", section on 'Those with SLNB prior to treatment'.)
The management of the axilla in patients receiving neoadjuvant therapy is briefly outlined below. It is discussed in much more detail in this algorithm (algorithm 2) and in another topic. (See "General principles of neoadjuvant management of breast cancer".)
Initial cN0 to cN1 disease and clinically node negative after neoadjuvant therapy — Patients who are initially clinically node negative, or patients with cN1 (metastasis to movable ipsilateral level I, II axillary lymph nodes) disease who become node negative after neoadjuvant therapy, are eligible for SLNB. This should, when possible, be combined with removal of any node that was positive by biopsy prior to neoadjuvant treatment and marked by a clip (referred to by some as targeted axillary dissection) (see 'Comparison of modalities' above). Further axillary treatment depends on the result of surgical axillary staging, as discussed in the sections below. (See 'Sentinel node identified and pathologically negative' below and 'Positive sentinel node(s)' below.)
There is no consensus on axillary management after neoadjuvant therapy in patients with clinically node-positive (cN+) breast cancer. In a 2022 survey by the European Breast Cancer Research Association of Surgical Trialists, the most common post-neoadjuvant therapy axillary surgery in patients with cN1 disease converting to ycN0 was targeted axillary dissection (54.2 percent), followed by SLNB alone (20.9 percent), level 1 to 2 ALND (18.4 percent), level 1 to 3 ALND (4 percent), and TLNB (2.5 percent) [96].
Sentinel node identified and pathologically negative — These patients (ypN0) do not require completion ALND. (See "General principles of neoadjuvant management of breast cancer", section on 'Management of the axilla'.)
The decision regarding whether axillary radiation is delivered depends on the initial stage, the response to therapy, and other high-risk features (see "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer", section on 'Patients who received neoadjuvant therapy'):
●Patients presenting with initial stage I disease (cN0) with a complete pathologic response in the breast and axilla are not treated with ALND or regional RT.
●Patients who initially presented with stage II disease who have a complete response to treatment need individualized decision making with regard to adjuvant regional RT, taking into account pretreatment risk factors. We would typically not administer radiation unless the patient had clinical N1 disease at presentation.
●For those who initially presented with stage III disease or those with any initial-stage disease who have residual breast disease, we offer regional RT, either in addition to WBRT after breast-conserving surgery or as a part of PMRT after mastectomy. However, we recognize that this approach is controversial, and our threshold to omit regional radiation in such patients is lower than for patients with residual nodal disease. (See "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer", section on 'Patients who received neoadjuvant therapy'.)
Positive sentinel node(s) — For patients with any positive sentinel node after neoadjuvant therapy (ypN+), we offer maximal axillary therapy consisting of completion ALND followed by regional RT. For now, ALND remains standard care in patients with residual disease after neoadjuvant chemotherapy while the results of Alliance A011202 (NCT01901094) are pending [97]. (See "General principles of neoadjuvant management of breast cancer", section on 'Management of the axilla' and "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer", section on 'Patients who received neoadjuvant therapy'.)
Initial cN2 or cN3 disease, or clinically node positive after neoadjuvant therapy — ALND followed by regional RT is also appropriate for patients with either initial cN2 or cN3 disease (metastasis in fixed/matted axillary nodes or internal mammary, infraclavicular, or supraclavicular nodes) or those with any stage disease found to have a persistently positive lymph node after neoadjuvant treatment. (See "General principles of neoadjuvant management of breast cancer", section on 'Positive axilla prior to treatment' and "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer", section on 'Patients who received neoadjuvant therapy'.)
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Breast surgery".)
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)
●Beyond the Basics topics (see "Patient education: Breast cancer guide to diagnosis and treatment (Beyond the Basics)")
SUMMARY AND RECOMMENDATIONS
●Axillary evaluation – Axillary physical examination is performed in all patients with breast cancer. Axillary ultrasound may be performed, although practice varies between centers. Percutaneous, ultrasound-guided needle biopsy should be performed for abnormal lymph nodes detected on ultrasound. (See 'Axillary evaluation' above.)
●Axillary management – The need for surgery, radiation, or both depends on the result of the axillary evaluation and whether the patient undergoes neoadjuvant therapy. (See 'Comparison of modalities' above.)
●Patients who do not undergo neoadjuvant therapy – Patients who do not require neoadjuvant therapy generally undergo either sentinel lymph node biopsy (SLNB) or axillary lymph node dissection (ALND) with their primary breast procedure (algorithm 1). (See 'Patients who do not undergo neoadjuvant therapy' above and "Overview of sentinel lymph node biopsy in breast cancer", section on 'Management after SLNB'.)
•Patients with clinically node-negative axilla should undergo SLNB, the result of which directs further treatment (see "Overview of sentinel lymph node biopsy in breast cancer"):
-Pathologically negative sentinel nodes – Patients who do not have nodal metastases on SLNB do not require ALND, and the majority do not require regional radiation therapy (RT). We offer regional RT for select patients with high-risk features, although this practice varies between centers. (See 'No positive sentinel node' above.)
-One or two positive sentinel node(s) – For such patients, we do not perform completion ALND, but for those who undergo mastectomy, we administer postmastectomy RT (PMRT). We offer regional RT for those who undergo breast-conserving therapy in addition to whole breast RT (WBRT), although this practice varies between centers. (See 'One or two positive sentinel nodes' above.)
-More positive sentinel nodes – For patients with three or more positive lymph nodes, we proceed with both completion ALND and regional RT. (See 'More positive lymph nodes' above.)
We recognize, however, that regional RT is controversial in those with fewer than four involved lymph nodes. (See 'More positive lymph nodes' above.)
•For patients with clinically bulky and biopsy-proven node-positive disease who do not undergo neoadjuvant treatment, we suggest ALND at the time of the primary breast procedure rather than SLNB or nodal radiation alone (Grade 2C). Patients with a positive node based on ultrasound-guided biopsy alone may undergo SLNB. (See 'Patients who do not undergo neoadjuvant therapy' above.)
The use of regional RT in such patients is discussed elsewhere. (See "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer", section on 'Involved lymph nodes'.)
•Select older patients with early-stage estrogen receptor (ER)-positive, HER-2/neu-negative tumors who are clinically node negative and who will receive adjuvant endocrine therapy may be managed without any axillary surgical assessment. (See 'Omitting axillary surgery' above.)
●Patients who undergo neoadjuvant therapy – After neoadjuvant therapy, the axilla should be reexamined clinically with or without another ultrasound (algorithm 2). (See 'Patients who undergo neoadjuvant therapy' above and "General principles of neoadjuvant management of breast cancer", section on 'Management of the axilla'.)
•Patients who are initially clinically node negative (cN0), or patients with cN1 disease who become pathologically node negative after neoadjuvant therapy, should undergo SLNB (with removal of any clipped node) at the time of surgery (after neoadjuvant chemotherapy), the result of which directs further treatment:
-Pathologically negative sentinel nodes – These patients (ypN0) do not require completion ALND. However, the decision regarding whether axillary radiation is delivered depends on the initial stage, the response to therapy, and other high-risk features. (See 'Sentinel node identified and pathologically negative' above.)
-Any positive sentinel node(s) – For patients with any number of positive sentinel nodes after neoadjuvant therapy (ypN+), we proceed with completion ALND followed by regional RT. (See 'Positive sentinel node(s)' above.)
•Patients with either initial cN2 or cN3 disease (regardless of response to neoadjuvant treatment), or a persistently positive lymph node after neoadjuvant treatment regardless of stage, should undergo ALND and regional RT. (See 'Initial cN2 or cN3 disease, or clinically node positive after neoadjuvant therapy' above.)
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