Prognoses of different pathological subtypes of colorectal cancer at different stages: A population-based retrospective cohort study

BACKGROUND: Whether the prognoses of different pathological subtypes of colorectal cancer (CRC) at different stages are distinct is unclear. METHODS: We extracted data on all cases of CRC from the Surveillance, Epidemiology, and End Results database between 2004 and 2015. The incidence of different pathological subtypes, clinical characteristics, and five-year overall survival (OS) and cause-specific survival (CSS) were analyzed. RESULTS: A total of 384,996 cases diagnosed as adenocarcinoma (AC), mucinous adenocarcinoma (MAC), and signet ring cell carcinoma (SRCC) were included in this analysis. Compared with AC, MAC and SRCC were more likely to reach T4, N2, M1, stages III and IV, and grades III and IV, and patients were generally of a younger age (P < 0.001). Compared with those with AC, patients with MAC and SRCC showed poorer OS (50.6 and 26.8% vs. 60.2%, P < .001), with corresponding HR values of 1.238 (95% CI, 1.213–1.263, P < .001) and 1.592 (95% CI, 1.558–1.627, P < .001), respectively. The MAC and SRCC groups also showed poorer overall CCS (60.9 and 32.5% vs. 67.8%, P < .001), with corresponding HR values of 1.271 (95% CI, 1.242–1.302, P < .001) and 1.724 (95% CI, 1.685–1.765, P < .001), respectively. Compared with patients with AC, those with MAC showed poor OS at every stage and poor CSS at every stage except stage II (P < .05), while patients with SRCC revealed poor OS and CSS at every stage except stage 0 (P < .05). CONCLUSIONS: Patients of different pathological subtypes minimally differed at early stages. However, patients with AC have significantly better prognoses in advanced CRC (stages III and IV) than those with MAC or SRCC. Distinct treatment strategies should be applied depending on a particular histological subtype in advanced CRC.