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Regorafenib, an oral multikinase inhibitor, has improved survival in metastatic colorectal cancer (mCRC) patients who have progressed on standard therapies. Our study aimed to evaluate prognostic factors influencing regorafenib treatment and assess the optimal dosing regimen in a real-life setting. We retrospectively analysed 263 patients with mCRC from multiple medical oncology clinics in Turkey. Treatment responses and prognostic factors for survival were evaluated using univariate and multivariate analysis. Of the patients, 120 were male, and 143 were female; 28.9% of tumors were located in the rectum. RAS mutations were present in 3.0% of tumors, while BRAF, K-RAS, and N-RAS mutations were found in 3.0%, 29.7%, and 25.9% of tumor tissues, respectively. Dose escalation was preferred in 105 (39.9%) patients. The median treatment duration was 3.0 months, with an objective response rate (ORR) of 4.9%. Grade ≥ 3 treatment-related toxicity occurred in 133 patients, leading to discontinuation, interruption, and modification rates of 50.6%, 43.7%, and 79.0%, respectively. Median progression-free survival (PFS) and overall survival (OS) were 3.0 and 8.1 months, respectively. RAS/RAF mutation (hazard ratio [HR] 1.5, 95% confidence interval [CI] 1.1-2.3; P = 0.01), pretreatment carcinoembryonic antigen (CEA) levels (HR 1.6, 95% CI 1.1-2.3; P = 0.008), and toxicity-related treatment interruption or dose adjustment (HR 1.6, 95% CI 1.1-2.4; P = 0.01) were identified as independent prognostic factors for PFS. Dose escalation had no significant effect on PFS but was associated with improved OS (P < 0.001). Independent prognostic factors for OS were the initial TNM stage (HR 1.3, 95% CI 1.0-1.9; P = 0.04) and dose interruption/adjustment (HR 0.4, 95% CI 0.2-0.9; P = 0.03). Our findings demonstrate the efficacy and safety of regorafenib. Treatment line influences the response, with dose escalation being more favorable than adjustment or interruption, thus impacting survival.

Purpose: Right-sided colon cancers (RCCs) and left-sided colon cancers (LCCs) have different embryological, epidemiological, physiological, pathological, genetic, and clinical characteristics, which result in differences in the course, prognosis, and outcome of disease. This study aimed to compare RCCs and LCCs regarding clinicopathological and survival characteristics., Methods: The present retrospective study included data of patients who were followed-up and treated for colon cancer from 2008 through 2017. Rectosigmoid, descending colon, and splenic flexure tumors were considered LCC, whereas hepatic flexure and ascending colon tumors were considered RCC. Tumors were staged according to the American Joint Committee on Cancer classification., Results: The study included 1725 patients (female, 58.7%) having colon cancer with a mean age of 64±12 years. Of the patients, 83.2% (n=1436) had LCC and 16.8% (n=289) had RCC. The rate of patients aged ≥65 years and the rate of patients with a family history of colon cancer were higher in the RCC patients. The rate of metastatic patients was 29.1% in the RCC group and 23.2% in the LCC group (p=0.087). The median follow-up period was 18 months in the RCC group and 23 months in the LCC group (p=0.011). Although the median survival time was higher in the LCC group (62 vs. 43 months), no significant difference was determined between the RCC and LCC groups in terms of survival., Conclusions: There are numerous clinicopathological differences between RCC and LCC and these differences are reflected in prognostic and survival differences among certain subgroups.