Long-Term Outcomes of Sigmoid, Rectosigmoid, and Rectal Cancers: A Matched Analysis

To determine a population-based comparative matched overall survival analysis for patients undergoing curative resection for sigmoid, rectosigmoid, and rectal cancers stage by stage.

Patients who underwent curative surgery for nonmetastatic adenocarcinoma of the sigmoid, rectosigmoid, and rectum between 2000 and 2020 were identified using the US SEER cancer registry data. Each anatomical subsegment was matched in a 1:1 ratio based on age, sex, time of surgery, grade of differentiation, and histopathological stage. Multivariate (MV) Cox regression analysis was conducted.

A total of 19,607 patients fulfilled the criteria per group. Whereas chemotherapy rates were comparable among groups, radiotherapy rates were significantly higher in the rectum. Compared to the initial time period (2000-2005), there was a significant improvement in 3- and 5-year overall survival rates for each stage in the time period of 2016-2020. During the study period, a 10% improvement was observed for Stage-2 and Stage-3 patients for each site (p < 0.05). MV analysis showed that sex (p < 0.001), primary cancer site (p < 0.001), year category (p < 0.001), age (p < 0.001), stage (p < 0.001), degree of differentiation (p < 0.001), and CTx status (p < 0.001) were independently associated with overall survival.

This large population-based, comprehensive registry study demonstrates significant survival differences among sigmoid, rectosigmoid, and rectal cancers. Further studies defining distinct landmarks between rectal and colon cancers may improve treatment approaches, cancer care, and survival.