Selective Benefit of Adjuvant Chemotherapy in Stage II dMMR Colon Cancer with High-Risk Features or Poorly...

The prognostic value of conventional high-risk factors and the benefits of adjuvant chemotherapy (ACT) in stage II colon cancer with deficient mismatch repair (dMMR) remain controversial. The function of ACT in stage II dMMR colon cancer and survival results were assessed in this research.

273 patients with stage II dMMR colon cancer who had curative resection between August 2010 and October 2023 underwent a retrospective analysis. Clinicopathologic variables, postoperative treatment strategies, and survival endpoints were systematically assessed. Independent prognostic factors were identified using a multivariable Cox proportional hazards regression model. For subgroup analyses, a propensity score-matched (PSM) approach was used to minimize intergroup imbalances. Overall survival (OS) and disease-free survival (DFS) were evaluated using the Kaplan-Meier approach.

177 (64.8%) patients had at least one high-risk factor. With a median follow-up of 62.6 months, the estimated 5-year OS and DFS rates were 94.7% and 89.8%. Age ≥ 65 years and examination of fewer than 12 lymph nodes were independently associated with OS. For DFS, age ≥ 65 years, LNs < 12, and receipt of ACT were identified as independent prognostic factors. According to subgroup analyses, ACT was linked to better OS and DFS in patients with high-risk features or poorly differentiated histology. Results were similar after propensity score matching.

Traditional high-risk features also exert prognostic impact on this population. ACT appeared to be associated with improved survival in selected high-risk patients, particularly those with poorly differentiated histology.