Depth of Tumor Invasion (T-Stage) is Not Associated with Survival or Recurrence Rates in Patients Undergoing Surgery for pT1 and pT2 Colon Cancer

BACKGROUND: Organ preservation is gaining attention, yet primary treatment approaches differ substantially between pT1 and pT2 colon cancer (CC). This study evaluates whether tumor invasion depth affects survival outcomes in patients with pT1-2N0-2 colon cancer.

METHODS: In this nationwide cohort study, patients undergoing surgery for pT1 or pT2 CC between 2014 and 2015 were identified from the Dutch Snapshot Research Group's SNAPSHOT complex colon cancer database. Five-year disease-free survival (DFS) and overall survival (OS) was analyzed using Kaplan-Meier curves, log-rank tests, and Cox proportional hazard models.

RESULTS: A total of 2312 patients were included (921 pT1 and 1391 pT2). Five-year DFS (83.5% vs. 83.2%, P = 0.79, adjusted HR [HR adj] pT2 vs. pT1: 0.9; 95% confidence interval [CI] 0.7-1.2) and 5-year OS (84.9% vs. 85.6%, P = 0.72, HR adj pT2 vs. pT1: 0.8; 95% CI 0.6-1.1) were comparable between pT1N0 and pT2N0 patients. Similarly, in pT1N+ and pT2N+ patients, there was no significant difference in DFS (81% vs. 75.8%, P = 0.31, HR adj pT2 vs. pT1: 1.3; 95% CI 0.6-2.6) or OS (84% vs. 82.5%, P = 0.73, HR adj pT2 vs. pT1: 0.9; 95% CI 0.5-1.6). Distant metastases developed in 37 (4%) pT1 patients and 68 (4.9%) pT2 patients (P = 0.33). Among these, 26 of 37 pT1 patients (70.3%) and 40 of 68 pT2 patients (58.8%) did not have lymph node metastases in the initial resection specimen (pN0).

CONCLUSIONS: Tumor invasion depth (pT1 or pT2) had no significant impact on DFS or OS following formal oncological resection. Furthermore, most distant metastases develop in pN0 patients, suggesting a minor influence of surgery on control of distant disease.