Effect of mutation on the prognosis for patients with colorectal cancer undergoing cytoreductive surgery for synchronous peritoneal metastasis.

Background: mutations (mutmut) are unfavorable prognostic factors for colorectal cancer (CRC) metastases to the liver and lungs. However, their effects on the prognosis for patients with synchronous peritoneal metastasis (S-PM) of CRC after cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) are controversial. In the study, we aimed to determine the effects of mutmut on the prognosis for patients with S-PM who received CRS.

Methods: A total of 142 patients diagnosed with S-PM between July 2007 and July 2019 were included in this study. The demographics, mutmut status, overall survival (OS), and progression-free survival (PFS) of the patients were evaluated. The Kaplan-Meier method and log-rank test were used to estimate the difference in survival between groups.

Results: Among 142 patients, 68 (47.9%) showed mut and 42 (29.5%) showed mut. The median OS values were 8.4 and 34.3 months for patients with mut and wild-type, respectively (<0.01). However, status was not significantly associated with median OS (=0.76). Multivariate analysis revealed carcinoembryonic antigen, CRS, HIPEC, and mut as independent predictors for OS. Based on these findings, a nomogram was constructed. The C-index was 0.789 (95% confidence interval, 0.742-0.836), indicating good predictive ability of the model. Furthermore, the 1- and 2-year survival calibration plots showed good agreement between the predicted and actual OS rates. The area under curves of the 1- and 2-year survival predictions based on the nomogram were 0.807 and 0.682, respectively. Additionally, mut was significantly associated with lower PFS (<0.001).

Conclusions: mut is an independent prognostic risk factor for S-PM. The established nomogram predicted the OS of patients with CRC having S-PM with high accuracy, indicating its usefulness as a valuable prognostic tool for the designated patient cohort.