Comparison of folfox and folfiri protocols at first-linetreatment in patients with metastatic colorectal cancer intreatment response and survival results according to primarytumor location

Objective: Various different factors are involved in the selection of chemotherapy protocols used in the treatment of patients with colorectal cancer. When determining the treatment regimen, we sought to determine the option that would be more effective depending on the region of the colon where the primary tumor is located. Methods: Our study was conducted with the involvement of patients diagnosed with colorectal cancer by biopsy at Akdeniz University Faculty of Medicine Hospital between the dates of 01.01.2014 and 30.08.2022. Among these patients, those who had metastatic disease at the time of diagnosis, those who continued the treatment process in this center, and those who were over 18 years of age were included. Patients' medical records were screened retrospectively. The patients were divided into two as right colon (cecum, ascending colon and hepatic flexure) and left colon (splenic flexure, descending colon, sigmoid and rectum) according to primary tumor sites. The patients' primary tumor sites, first-line chemotherapy regimens, Anti-VEGF or Anti- EGFR agents they received in addition to chemotherapy, overall survival, progression-free survival, and treatment responses were studied. Results: A total of 82 patients participated in the study. 69.5% of them were men and 30.5% were women. The average age was found to be 59.6. Tumors located in the right colon, left colon and rectum were detected in 34.1%, 42% and 23.2%, respectively. When the first-line chemotherapy protocols of the patients were examined, 56.1% (46 patients) used FOLFOX, while 43.9% (36 patients) used FOLFIRI. KRAS/NRAS gene mutation was found to be negative in 61.0% of the patients and positive in 34.1%. When the BRAF gene was examined, data could not be obtained in most patients, and 86.2% of the data that could be determined had negative results and 13.8% had positive results. When the location of the primary tumor and the chemotherapy regimens received in the first line were compared, it was observed that there was no statistically significant difference between the patients' overall survival, progressionfree survival and treatment responses. viii Conclusion: Analyzes in our study showed that the location of the primary tumor did not directly affect the choice of first-line chemotherapy regimen in patients diagnosed with metastatic colorectal cancer. In this sense, clinician decision is important in choosing treatment. Keywords: Stage-IV Colorectal Cancer, Right Colon, Left Colon, FOLFOX, FOLFIRI, Overall Survival, Progression-Free Survival, Treatment Response