Analysis of the risk of metachronous colorectal cancer and long-term prognosis in patients following gastrectomy for gastric cancer

The impact of gastrectomy on the risk of developing second colorectal cancer (SCRC) in gastric cancer patients remains unclear. This study aimed to evaluate the association between gastrectomy and SCRC in gastric cancer patients. A total of 17,606 patients with gastric cancer were identified from the SEER database and categorized into gastrectomy (GT) and non-gastrectomy (NGT) groups. Fine-Gray competing risk analysis was employed to calculate the cumulative incidence of SCRC in different groups. Competing risk analysis and Poisson regression were used to assess the association between gastrectomy and SCRC risk. Standardized incidence ratios (SIRs) were calculated to compare CRC incidence in the GT and NGT groups with that in the general US population. A total of 128 patients in the GT group (0.8%) and 9 patients in the NGT group (0.4%) developed SCRC. Gastrectomy was identified as a significant adverse factor in both univariate and multivariate Poisson regression analyses. SIRs revealed a higher CRC incidence in the GT group compared to the general population, while the NGT group showed no significant difference. Gastrectomy is associated with an increased risk of SCRC in gastric cancer patients and significantly improves survival in those who develop SCRC.