Clinical impact of first-line bevacizumab plus chemotherapy in metastatic colorectal cancer of mucinous histology: a multicenter, retrospective analysis on 685 patients.

PURPOSE In metastatic colorectal cancer (MCRC), mucinous histology has been associated with poor response rate and prognosis. We investigated whether bevacizumab combined with different chemotherapy regimens may have an impact on clinical outcomes of MCRC patients with mucinous histology. METHODS 685 MCRC patients were classified in mucinous adenocarcinoma (MC) and non-mucinous adenocarcinoma (NMC) and were treated with first-line bevacizumab plus fluoropyrimidine (FP)-based, oxaliplatin (OXA)-based, irinotecan (IRI)-based, or FOLFOXIRI. RESULTS Ninety-four (13.7%) patients had MC. With a median follow-up of 50 months, MC patients had a median overall survival (OS) of 28.2 months compared with 27.7 months for the NMC group [hazard ratio (HR) = 0.92; 95% confidence interval (CI) 0.70-1.19, P = 0.530]. The overall response rates for MC and NMC were 41.5% (95% CI 31.5-51.4) and 62.4% (95% CI 58.4-66.3), respectively (Chi-square test, P <0.003). After correcting for significant prognostic factors by multivariate Cox regression analysis, age, resection of the primary tumour, and number of metastatic sites were found to be associated with poorer OS, but not mucinous histology. CONCLUSION Compared with NMC, MCRC patients with mucinous histology treated with bevacizumab plus chemotherapy had comparable OS despite lower overall response rate.