Treatment of newly diagnosed cT2N0 rectal adenocarcinoma or cT1 disease not amenable to local excision

MRI: magnetic resonance imaging; EUS: endoscopic ultrasound; CT: computed tomography; FDG-PET: fluorodeoxyglucose positron emission tomography; LAR: low anterior resection; APR: abdominoperineal resection.
* T1 tumors invade through the muscularis mucosa but not into the muscularis propria. T2 tumors invade the muscularis propria but not into the pericolorectal tissues.
cT1 tumors with all of the following features are amenable to local excision:

• Superficial T1 cancer, limited to the submucosa
• No radiographic evidence of metastatic disease to regional nodes
• Tumor <3 cm in diameter
• Low risk of developing positive regional nodes (well-differentiated, no lymphovascular or neural invasion)
• Involves <30% of the circumference of the lumen
• Mobile, nonfixed
• Margins clear (>3 mm)
• Compliance with appropriate postoperative surveillance

¶ CT is appropriate for all except those with clinical T1N0 cancers with favorable histologic factors.

• If pelvic MRI has been done, we perform CT of the chest and abdomen
• If pelvic MRI has not been done, we perform CT of the chest, abdomen, and pelvis

Δ Patients who refuse surgery or are considered poor surgical candidates after chemoradiotherapy may be managed by full thickness local excision after chemoradiotherapy. Highly selected patients who appear to have a complete clinical response (scar only) may be considered for full thickness local excision or "watch and wait" but should understand that transabdominal surgery represents a standard approach in this setting. More extensive residual disease at the time of local excision should prompt reconsideration for transabdominal surgery.
◊ Transabdominal surgery may not be feasible for patients with more advanced tumors (eg, T2N0 or higher stage) if they have significant medical comorbidities, refuse transabdominal surgery, or have an estimated short life expectancy for whatever reason.