Clinical characteristics and survival trends of patients with metastatic colorectal cancer (mCRC) and peritoneal carcinomatosis who receive metastases surgery in a Spanish cohort.

Abstract

159 Background: Peritoneal metastases in patients with mCRC are commonly associated with poor outcomes. Some of these patients are candidates to undergo metastases surgery, which may result in better prognosis; however, clinical and molecular characteristics of these patients remain uncertain. Methods: We conducted a retrospective analysis of 166 patients with mCRC and peritoneal metastases in a tumor registry from 2015 to 2021, analyzing the clinical and molecular characteristics, as well as progression-free survival (PFS) and overall survival (OS) of patients who received peritoneal surgery versus those who did not. Results: From the whole population, 65 patients (39%) underwent peritoneal metastases surgery, and several characteristics were more frequent in this subgroup: ECOG 0 (n = 26, OR 2.75, p = 0,0069), age <65 years (n = 43, OR 2.29, p = 0,0162), absence of hepatic metastases (n = 56, OR 3.31, p = 0,0037), single metastatic location (n = 43, OR 3.48, p = 0,0002), normal CEA levels at diagnosis (n = 33, OR 2.02, p = 0,0455) and BRAF mutation (n = 12, OR 3.32, p = 0,0345). Moreover, these patients received more lines of systemic treatment (2.8 vs 2, p = 0,006) and more metastases surgeries (1.7 vs 0.9, p = 0,000). Significant differences in tumor mutational status regardless of BRAF (KRAS, NRAS, MSI, PI3K and HER2), sex and primary tumor location between groups were not found. PFS was longer in patients receiving metastases surgery (median, 13.68 vs 7.76 months; HR for progression 0.64; 95 % confidence interval (CI) 0.46 to 0.89; p = 0,009), as well as overall survival (median NR vs 29.53; HR for death 0.39; 95 % CI, 0.25 to 0.60; p = 0,000). Conclusions: In our cohort, patients with mCRC and peritoneal carcinomatosis who underwent metastases surgery had more frequently less than 65 years, ECOG 0, absence of liver metastases, single metastatic location, normal CEA levels at diagnosis and BRAF mutation. Moreover, this subgroup showed better outcomes with a statistically significant increase in PFS and OS.