Impact of gross tumor morphology on the clinical outcomes of colon cancer: multicenter retrospective cohort study.

[PURPOSE] While histopathological features are established prognostic factors in colorectal cancer, the prognostic significance of gross tumor morphology remains unclear. We investigated whether endoscopic gross morphology is associated with clinical outcomes in colon cancer.

[METHODS] We performed a multicenter retrospective analysis of 1,177 patients with colon cancer who underwent curative-intent endoscopic or surgical resection between 2010 and 2019. Tumors were categorized based on endoscopic images as flat/ulceroinfiltrative (n = 345) or fungating/ulcerofungating (n = 832). Kaplan-Meier analysis assessed survival outcomes, and Cox proportional hazards models identified independent prognostic factors, adjusting for age, sex, family history, diabetes, CEA, and AJCC 7th edition stage.

[RESULTS] Patients with flat/ulceroinfiltrative tumors had significantly shorter overall survival (OS, p = 0.001) and disease-free survival (DFS, p = 0.024) than those with fungating/ulcerofungating tumors. In stage II patients, the difference in OS by morphology was more pronounced (p = 0.004). Multivariate analysis confirmed flat/ulceroinfiltrative morphology as an independent predictor of poor OS (HR 1.61; 95% CI 1.122-2.335; p = 0.010). Other significant predictors included older age (≥ 65 years, HR 1.533; p = 0.021), poor histologic grade (PD vs. WD/MD, HR 5.308; p < 0.001), and advanced stage.

[CONCLUSIONS] Gross endoscopic morphology is an independent prognostic factor in colon cancer. Flat/ulceroinfiltrative tumors are associated with worse outcomes, especially in stage II disease. Gross morphology, readily identifiable at diagnosis, may aid risk stratification and inform decisions regarding adjuvant therapy.