Treatment and prognosis of colorectal cancer with synchronous peritoneal metastases: 11-year single institute experience

Background Treatment of colorectal cancer (CRC) with synchronous peritoneal metastases (SPM) is controversial, and its prognosis remains poor. Here, we analysed the association between treatment strategies and the outcomes of patients with colorectal SPM and devised a nomogram to improve their prognosis prediction. Methods We retrospectively analysed patients with colorectal SPM treated at The Sixth Affiliated Hospital, Sun Yat-sen University from June 2007 to June 2018. The Kaplan-Meier method with log-rank tests was used to compare the overall survival (OS) among patients undergoing different therapeutic regimens. Cox proportional hazards regression analysis was used to identify the prognostic factors. After variable selection, a nomogram was developed to predict the OS of patients with colorectal SPM. Results A total of 371 patients with colorectal SPM were eligible for this study. The median OS of all patients was 15.0 months (95% CI, 13.1 to 16.9), with a 3-year and 5-year OS rate of 23.7% and 16.9%, respectively. Patients who underwent complete cytoreductive surgery (CC0–1) had a better median OS of 49 months (p<0.001). Cox multivariate analysis showed that age >65 years; cancer antigen 125 level >35 U/mL; peritoneal carcinomatosis index >16 scores; and undergoing cytoreductive surgery, chemotherapy and hyperthermic intraperitoneal chemotherapy were independent prognostic factors for OS. The c-index of the prognostic nomogram was 0.747 (95% CI, 0.474 to 1.020). Conclusions Our study suggests that patients with colorectal SPM who receive comprehensive treatment might achieve better prognoses. The prognostic nomogram demonstrated good predictive performance for patients with colorectal SPM.