Revisiting the survival paradox between stage IIB/C and IIIA colon cancer

Patients with stage IIB/C (T4a-bN0) colon cancer often exhibit worse survival rates compared to those with stage IIIA (T1-2N1, T1N2a) colon cancer. This study re-evaluates the survival paradox using the latest Surveillance, Epidemiology, and End Results (SEER) data (released on April 17, 2024) to inform potential revisions to the staging criteria. Utilizing SEER data with 8th edition TNM staging criteria, 4692 colon cancer patients diagnosed between 2018 and 2021 were analyzed with chi-square test. Cox regression and Kaplan-Meier survival analysis were employed to assess factors associated with cancer-specific survival (CSS) and overall survival (OS). The 3-year CSS rates for stage IIB and IIC were 73.1% and 70.3%, respectively, whereas stage IIIA had a substantially higher CSS rate of 91% (P < 0.001). Similarly, the OS rates were 64.9% and 63.0% for stage IIB and IIC, respectively, compared to 83.1% for stage IIIA (P < 0.001). Multivariate analyses revealed stage IIIA patients had significantly lower risks of cancer-specific mortality (hazard ratio (HR) = 0.374, 95% CI: 0.296-0.473, P < 0.001) and overall mortality (HR = 0.575, 95% CI: 0.483-0.685, P < 0.001) compared to stage IIB patients. The upcoming 9th edition of the AJCC staging system should address this paradox by integrating advanced diagnostic markers and emphasizing the aggressive biology of T4 tumor, providing more accurate prognostic information and guiding more effective treatment strategies for colon cancer patients.