Optimization and Standardization of Single-Port Robotic Transanal Minimally Invasive Surgery for Rectal Tumor Excision

Inclusion Criteria: * Patients with benign rectal lesions, including large adenomas or polyps not amenable to standard endoscopic removal * Patients with recurrent or residual rectal lesions following incomplete endoscopic resection * Patients with early-stage rectal cancer (clinical T1 tumors confined to the submucosa) with favorable histologic features (e.g., well-differentiated, no lymphovascular or perineural invasion) * Select patients with T2 rectal cancer who are medically unfit for radical surgery or require local palliation * Patients with clinically downstaged rectal cancer (e.g., cT0 or near-complete response) following neoadjuvant chemoradiotherapy, in whom TAMIS may be used for local excision to confirm pathological response Exclusion Criteria: * Patients undergoing excision of rectal neuroendocrine tumors * Patients with bulky tumors or advanced disease (clinical T3-T4) * Patients with radiologic or clinical evidence of nodal involvement * Patients with high-risk histologic features (e.g., lymphovascular invasion, perineural invasion, poor differentiation), unless TAMIS is performed for palliative purposes or in patients unfit for radical surgery * Patients in whom completion radical surgery is clearly indicated based on preoperative assessment