Primary Tumor Size as a Predictor of Prognosis in Patients with Stage IV Colorectal Cancer: Population analysis based on two centers

Background: The prognostic significance of primary tumor size in patients with stage IV colorectal cancer (CRC) has not been established. This study aimed to evaluate the prognostic value of tumor size in stage IV CRC. Methods We retrospectively analyzed the data of patients with stage IV CRC in the Surveillance, Epidemiology and End Results (SEER) database and patients with stage IV CRC treated at the Sixth Affiliated Hospital of Sun Yat-sen University (SYSU). The optimal cutoff value for tumor size was determined using the X-Tile program. Multivariable Cox regression analysis were used to examine whether tumor size was an independent predictor of prognosis. Results There were 16,283 patients in the SEER cohort and 462 in the SYSU cohort. With the help of the X-Tile program, we selected 60mm as the optimal tumor size cutoff. Multivariate analysis confirmed that tumor size (HR = 1.17, 95%CI: 1.13–1.22) was an independent prognostic factor in stage IV CRC. Across all subgroups in the SEER cohort, survival probability was significantly lower in patients with tumor size ≥ 60 mm than in patients with tumor size < 60 mm. Conclusions Tumor size appears to be an independent predictor of survival in patients with stage IV CRC. Patients with tumor size ≥ 60 mm have poor prognosis.