For a T1 N0 rectal adenocarcinoma at 3 cm from the anal verge, confined to the submucosa (sm1), which local excision technique and oncological criterion determine adequacy of treatment without radical resection?

• A Endoscopic mucosal resection; tumor size <2 cm with negative horizontal margins
• B Transanal endoscopic microsurgery (TEM); margins >1 mm, well/moderate differentiation, no lymphovascular invasion ✓
• C Parks posterior proctotomy; with adjuvant radiotherapy regardless of histology
• D Anterior resection is always required for tumors at this level due to nodal risk

Explanation

For T1 rectal cancers, local excision via transanal endoscopic microsurgery (TEM) or transanal minimally invasive surgery (TAMIS) is acceptable for tumors with favorable histology. Criteria for safe local excision include: submucosal invasion level sm1 (upper third), well or moderate differentiation, no lymphovascular invasion, no perineural invasion, clear deep margin >1 mm, and tumor <3 cm. These criteria correspond to a lymph node metastasis risk of <3%, similar to the mortality risk of radical resection. T1 sm3 tumors have 20-23% nodal metastasis risk and require radical resection. Completion radical surgery is recommended if pathological examination reveals adverse features post-local excision.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

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Written and medically reviewed by the StethoPrep medical team.