Tumor size as a prognostic factor improves the accuracy of the prognostic prediction of T4 stage colon cancer: a propensity score analysis

Abstract The aim of this study was to evaluate the potential impact of tumor size on the long-term outcome of CC patients after curative surgery. A total of 782 curatively resected T4 stage CC patients without distant metastasis were enrolled. Patients were categorized into 2 groups according to the best threshold of tumor size: larger group (LG) and smaller group (SG). Propensity score matching was used to adjust for the differences in baseline characteristics. The ideal cutoff points for tumor size was 5 cm. In the multivariate analysis for the whole study series, tumor size was an independent prognostic factors. Patients in the LG had a significant lower 5-year OS rate, but higher distant metastatic rate than those in the SG (37.1% versus 25.2%, P < 0.001). After matching, patients in the LG still demonstrated a significant lower 5-year OS rate than those in the SG (63.5% versus 74.2%, P < 0.001). Patients in the LG benefited more from postoperative adjuvant chemotherapy than patients in the SG. The modified stage including tumor size was found to be more appropriate for predicting the OS of T4 stage CC than TNM stage. In conclusion, tumor size was an independent prognostic factor and could correlate with higher distant metastasis rate and better response of adjuvant chemotherapy. We maintain that tumor size should be incorporated into the staging system to enhance the accuracy of the prognostic prediction of T4 stage CC patients.