Mucinous Histology In Advanced Colorectal Cancer Patients Treated With First-Line Irinotecan- And/Or Oxaliplatin-Based Chemotherapy

4120 Background: Recently, patients with advanced mucinous colorectal cancer (MCRC) were found to have a poorer response to fluorouracil-based first-line chemotherapy and reduced survival compared with patients with non-mucinous colorectal cancer (NMCRC) (Ann Oncol 2005; 16:1305–10). Todate, regimens containing fluoropyrimidines and irinotecan (IRI) or oxaliplatin (OXA) are considered standard for the first line chemotherapy of advanced colorectal cancer. The aim of this study was to investigate the efficacy of IRI and/or OXA in combination with fluoropyrimidines as first-line chemotherapy in patients with advanced MCRC. Methods: The study population consisted of patients with advanced/metastatic colorectal cancer followed at 5 oncology centers (years 2001–2006). Prognostic factors associated with overall response rate (ORR) and overall survival (OS) were identified using univariate and multivariate logistic and/or Cox proportional hazards analyses. Results: The study included 255 patients, M/F 153/102, median age 67 years (range, 43–89), locally advanced/metastatic 11/244, 49 MCRC and 206 NMCRC. First-line chemotherapy included IRI-based (MCRC/NMCRC 9/56), OXA-based (MCRC/NMCRC 34/135), and OXA/IRI-based (MCRC/NMCRC 6/15) regimens. The ORRs for MCRC and NMCRC were 18.4% (95% CI, 7.5% to 29.2%) and 49% (95% CI, 47.2% to 55.8%), respectively (chi-test, p<0.001). With a median follow-up of 45 months, median OS for the MCRC patients was 14.1 months compared with 23.4 months in the NMCRC group (hazard ratio, HR=1.74; CI 95%, 1.27–3.31; p=0.003). After correcting for significant prognostic factors by multivariate Cox regression analysis, mucinous histology was associated with poorer OS (HR=1.59, 95% CI, 1.057–2.401; p=0.026) together with number of metastatic sites (2–4 versus 0–1; HR=1.47; 95% CI, 1.04–2.08), peritoneal disease (present versus absent; HR=1.58; 95% CI, 1.01–2.49), and performance status (2 versus 0–1; HR=3.52; 95% CI, 2.07–5.99). Conclusion: Patients with MCRC have poor responsiveness and survival to IRI and/or OXA-based first-line chemotherapy compared with NMCRC patients. No significant financial relationships to disclose.