A retrospective analysis on first-line bevacizumab, cetuximab, and panitimumab-containing regimens in patients with RAS-wild metastatic colorectal cancer: A Collaborative Study by Turkish Oncology Group (TOG).

Purpose: To compare the efficacy and adverse effect profiles of the first-line treatment of patients with KRAS wild type metastatic colorectal cancer (CRC) in Turkey who were treated based on regimens including bevacizumab, cetuximab and panitumumab.
Methods: This retrospective multicenter observational study involved a total of 238 patients who received chemotherapy in combination with either bevacizumab or cetuximab or panitumumab as first-line therapy for KRAS wild-type metastatic colorectal cancer. Patients with full medical records having pathological diagnosis of CRC adenocarcinoma were included in the study. The demographic, laboratory, histopathological and clinical characteristics of the patients were determined, and three groups were compared based on the study variables.
Results: The mean age of the entire sample (n=238) was 58±11 years, 64% of which were male. The most frequent tumor localization was the rectum (37%) and G2 was the most common tumor grade (59.7%). About 63% of the patients had metastatic disease at diagnosis, with the most common site of metastasis being lung (14.7%) and liver (52.5%). Overall survival (OS) was 63.9%, while 1-, 3- and 5-year survival rates were 91.7, 56.6 and 36.9%, respectively. The expected mean survival was 49.1 months (95% CI, 42.9-55.3). The 1-, 3- and 5-year progression-free survival (PFS) rates following first-line treatment were 65.3, 26.1 and 5.6%, respectively, while disease free survival (DFS) in patients without metastasis at diagnosis was 68.5%. An analysis carried out disregarding which treatment the patients received (FOLFOX or FOLFIRI) revealed that a panitumumab-containing combination resulted in poorer prognosis compared to bevacizumab or cetuximab-containing combination (p<0.001). With regard to the adverse effect profile, the most common adverse effects were neuropathy and neutropenia in patients receiving FOLFOX-bevacizumab; neutropenia and perforation in patients receiving FOLFIRI-bevacizumab; rash and pustular infection in patients receiving FOLFIRI-cetuximab; and diarrhea in patients who received FOLFIRI-panitumumab combination.
Conclusion: This is the first multicenter study performed in Turkey evaluating the response to treatment and adverse effects in patients with KRAS wild-type metastatic colorectal cancer.