First-line treatment choices of Turkish medical oncologists in metastatic colorectal cancer: A survey study.

Purpose: Colorectal cancer is one of the most common malignancies in the World. RAS-BRAF mutational status and primary tumor location are also important factors for the selection of optimal combinations therapies. In this study, we aimed to evaluate the Turkish oncologists' treatment decisions depending on tumor location and mutational status in metastatic colorectal cancer.

Methods: An online survey link was sent to the medical oncologists who are registered to Turkish Society of Medical Oncology via e-mail and mobile applications.

Results: Ninety-four oncologists (85.5%) reported that tumor localization affects their treatment modality. In RAS-BRAF wild type left colon tumors, Turkish oncologists mostly use chemotherapy and anti-EGFR therapy (90.1%) for the first-line treatment, while on the right side, oncologists favored anti-VEGF therapy in combination with chemotherapy (65.5%). BRAF-mutant tumors in left colon had nearly the same rates of treatment tendency with both anti-VEGF and anti-EGFR antibodies in combination with chemotherapy, while in right-sided tumors the main treatment selection of the participants was anti-VEGF-based treatment (83.6%). In RAS-mutant patients, a great number of oncologists selected anti-VEGF-based treatment. On the right and left colon tumors, anti-VEGF treatment options ratios were 91.7 and 92.7%, respectively. Maintenance treatment is usually preferred by oncologists in both anti-VEGF and anti-EGFR-based treatment.

Conclusion: Turkish oncologists are considering tumor sidedness as an indicator for treatment individualization of patients. The selection of monoclonal antibodies is being affected by tumor localization and mutation status.