Purpose: Patients with Kirsten rat sarcoma viral oncogene wild-type (KRAS WT) metastatic colorectal cancer (mCRC) treated in first line with bevacizumab (B) or cetuximab (C) plus standard chemo backbones had comparable outcomes in phase III Cancer and Leukemia Group B (CALGB) 80405. We examined comparative effectiveness of B and C regimens in real-world community settings.
Methods: This retrospective study examined progression-free survival (PFS) and OS in a US community sample of KRAS WT mCRC patients treated with first-line B (n = 254) or C (n = 146) regimens. Medical records from the Vector Oncology Data Warehouse were used. Disease progression was determined from patient charts. OS was measured from the start of first-line treatment until death.
Results: There were no significant difference in either PFS or OS respectively between B-treated compared to C-treated patients (HR = 1.324, 95% CI 0.901, 1.947; HR = 1.080, 95% CI 0.721, 1.617). More B patients received oxaliplatin backbones (74.8 vs. 36.3%), and more C patients received irinotecan backbones (51.4 vs. 20.1%), ps < 0.001. Multivariate survival analyses showed a significant difference indicating a greater risk for death among C-treated patients with right-sided tumors vs. left-sided tumors (HR = 2.263, 95% CI 1.394, 3.673, p = 0.0009), but not for B-treated patients (HR = 1.209, 95% CI 0.825, 1.771, p = 0.3297).
Conclusions: Consistent with CALGB 80405, median PFS and OS for these community oncology KRAS WT mCRC patients treated with first-line B or C regimens did not differ significantly.
Keywords: Community oncology; Comparative effectiveness; Overall survival; Progression-free survival; Tumor location.