593P - Clinical Outcome of Systemic Chemotherapy for Colorectal Peritoneal Carcinomatosis

Abstract

ABSTRACT Background Peritoneal carcinomatosis (PC) is the second leading cause of death in patients with metastatic colorectal cancer. Despite improved survival after cytoreduction and hyperthermic intraperitoneal chemotherapy, systemic chemotherapy is not typically considered. Purpose This study investigated the characteristics and clinical outcomes of colorectal PC patients treated with systemic chemotherapy. Methods This was a retrospective review of patients with colorectal PC presenting to the National Cancer Center Hospital from July 2004 to October 2009. Data collected included patient characteristics, sites of metastases, chemotherapy regimen, histopathological data, gene variations (KRAS and BRAF), and duration of survival. Results PC was confirmed in 50 patients. The median overall survival (OS) of the PC patients were similar to those of the non-PC patients (n = 133) (23 vs. 25 months, p = 0.94). In the PC group, 37 patients (74%) were treated with an oxaliplatin regimen and 9 patients (18%) were treated with an irinotecan regimen as first-line chemotherapy, among whom 15 patients (30%) also received bevacizumab combined with oxaliplatin or irinotecan. Although there was no statistically significant difference in progression-free survival (PFS) between oxaliplatin (10 months) and irinotecan (8 months) regimens (p = 0.58), addition of bevacizumab resulted in longer PFS (18 months) compared to those without bevacizumab (9 months) (p = 0.26). The median OS for patients with isolated PC was 32 months, compared with 20 months for PC patients with extraperitoneal metastases (p = 0.08). Of 50 patients, 33 patients (66%) had available gene status results. KRAS mutations were found in 36% of patients, while BRAF mutations were identified in 20%. The treatment effect on OS in the wild-type BRAF group was greater compared to the mutant group (32 vs. 18 months, p = 0.16). Conclusion Colorectal PC versus non-PC derive the same benefits from systemic chemotherapy, and optimal regimens warrant further prospective study. Disclosure All authors have declared no conflicts of interest.