Does Omitting Additional Surgery After Local Resection Affect Oncological Outcomes in Patients with High-Risk pT1...

Colorectal cancer (CRC) is a leading cause of cancer-related mortality in Spain, with pT1 adenocarcinomas often managed via endoscopic polypectomy (EP). Determining the necessity of additional surgery post-EP remains challenging, especially given the low incidence of intramural residual tumor (IRT) and lymph node metastasis (LNM) in certain high-risk cases. This study aims to evaluate histological factors predicting residual disease and to explore strategies to reduce unnecessary completion surgeries.

We analyzed data from 276 patients with pT1 CRC arising from colonic and upper rectal polyps treated with complete EP at our institution between 2013 and 2021. pT1-polyps with positive resection margins, deep submucosal invasion ≥ 2 mm, presence of lymphovascular invasion, high-grade tumor budding, unfavorable histology, or indeterminate polyps were considered high-risk pT1-polyps. Patients were stratified into low-risk (LR), high-risk endoscopic management (HR-E), and high-risk surgical management (HR-S) groups. Follow-up involved clinical, endoscopic, and imaging surveillance over a median of 70 months. IRT, LNM, recurrence, and survival outcomes were analyzed.

Of the 276 patients, 88 (32%) were low-risk managed endoscopically, while 188 (68%) exhibited high-risk features; 128 underwent surgery (HR-S), and 60 were managed with surveillance (HR-E). Residual disease was identified in 18.7% of surgical specimens. IRT was predominantly associated with positive margins (p = 0.01). Unfavorable histology was strongly linked to LNM (p = 0.000). Recurrence rates were similar between HR-E and HR-S groups in patients with a single risk factor, with local recurrences effectively managed surgically. No CRC-specific deaths occurred in the HR-E group, and overall survival was better among patients with lower ASA scores and favorable histology.

Positive resection margins and unfavorable histology are significant predictors of IRT and LNM in pT1 CRC. Careful patient selection and vigilant follow-up may allow safe deferral of completion surgery in selected high-risk patients, especially those with comorbidities or a single histological risk factor, thereby reducing surgical morbidity without compromising survival.