Treatment of adenocarcinoma of unknown primary site

CMP: comprehensive molecular profiling; CUP: cancer of unknown primary; IHC: immunohistochemistry; MCCA: molecular cancer classifier assay; MSI-H: high microsatellite instability; TMB-H: high tumor mutational burden.

* Specific clinicopathologic subgroups include the following. Refer to UpToDate content on adenocarcinoma of unknown primary site for treatment strategies.

• Females with peritoneal carcinomatosis, who are treated similar to patients with ovarian cancer.
• Females with axillary lymph node metastases, who are treated similar to patients with breast cancer.
• Males with skeletal metastases and elevated prostate-specific antigen levels, who are treated similar to patients with prostate cancer.
• Patients with specific tumor profiles (ie, colon cancer, lung cancer, kidney cancer, thyroid cancer, among others).

¶ Site-specific therapy includes the use of first- and subsequent-line chemotherapy, targeted therapy, and immunotherapy indicated for the tumor type or predicted to be effective on CMP regardless of tumor type (eg, TMB-H, MSI-H tumors).

Δ If CMP identifies molecular alterations that are not part of standard treatment for that tumor type, such targeted therapy may be used at some point during the disease course.

◊ Options include carboplatin plus paclitaxel, gemcitabine plus either cisplatin or carboplatin, and gemcitabine plus irinotecan. All these regimens have similar efficacy, and selection of therapy is based on patient and provider preference regarding relative toxicities.

§ Molecularly-guided therapy is the selection of therapy (eg, targeted agents and/or immunotherapy) based on molecular alterations identified by CMP, in the absence of a known tissue of origin. The optimal sequencing of molecularly-guided therapy and empiric chemotherapy (eg, concurrent versus sequential use) has not been determined. For patients with advanced MSI-H or TMB-H tumors, refer to UpToDate content for management.