Staging Paradox and recurrence pattern among stage IIB, IIC, and IIIA Colon cancers: a retrospective cohort study

The survival rates of patients with stage IIB and IIC colon cancer are paradoxically inferior to that of patients with stage IIIA colon cancer. This study aimed to examine the oncological outcomes and investigate the factors that could affect the staging paradox among stage IIB, IIC, and IIIA colon cancers based on a 9-year cancer database.

Patients with stage IIB (pT4aN0M0), IIC (pT4bN0M0), or IIIA (pT1-2N1M0) colon cancer were retrospectively selected from a prospectively maintained medical database from January 2011 to December 2019. Factors that might influence the staging paradox, including radicality, harvested lymph nodes, and chemotherapy administration, were examined.

A total of 282 patients (stage IIB, n = 59; stage IIC, n = 46; and stage IIIA, n = 177) were enrolled. Patients with stage IIB/C cancer demonstrated higher carcinoembryonic antigen levels, larger tumor size, more frequent tumor obstruction, and higher locoregional recurrence than those with stage IIIA cancer. With respect to 10-year locoregional recurrence-free survival and cancer-specific survival, patients with stage IIB and IIC cancers had significantly lower survival rates than did those with stage IIIA cancer (73.7% vs. 66.3% vs. 91.2%, P = 0.0003; 5.4% vs. 10.9% vs. 11.2%, P = 0.0023). The staging paradox persisted in patients who underwent R0 resection, had harvested lymph nodes ≥ 12, and received chemotherapy, as confirmed by multivariate regression analysis.

Based on the inferior oncological outcomes and higher locoregional recurrence rate, this study highlighted the need for intensified cytotoxic chemotherapy specific to this recurrence pattern for patients with stage IIB/C colon cancer.