Profile of patients of colon cancers treated without any targeted therapies and comparison of treatment outcome between left- and right-sided tumors: A retrospective study from a tertiary cancer center in South India

Abstract

Introduction: Left- and right-sided colon cancers differ in pathology, tumor biology, and response to therapies. In our country, most of the patients with carcinoma of colon, do not afford targeted therapies and are treated with chemotherapy only, for their metastatic diseases. Aims: The present study aimed to find out differences in terms of survival outcomes between right- and left-sided colon carcinoma patients who were treated without any targeted therapy or immunotherapy. Materials and Methods: Retrospectively, data of patients of carcinoma colon who were diagnosed and treated in between January 2010 and August 2017 were collected. The different clinicopathological and survival parameters were compared between right-sided and left-sided colon carcinoma patients using Kaplan–Meier models, unadjusted Cox regression models, and Cox models stratified by stage. Results: Mean disease-free survival (DFS) for Stage I, II, and III patients was 37.9 months, 33.7 months, and 28.9 months, respectively, and mean progression-free survival (PFS) in 1st line for metastatic disease was 8.1 months. Mean PFS for metastatic diseases in 1st line was not different significantly between left- and right-sided tumors (left vs. right: 8.1 months vs. 8.5 months, P = 0.72). For nonmetastatic disease, mean overall survival (OS) was significantly better in left-sided tumors (left vs. right: 46.2 months vs. 39.6 months, P = 0.019). Those with metastatic disease at presentation, OS did not vary with side (left vs. right: 24.5 months vs. 24.2 months, P = 0.89). Among the patients, who had undergone curative surgery, either upfront or after conversion chemotherapy, left-sided tumors were found to have higher mean DFS and OS (left vs. right, DFS: 31.2 months vs. 20.4 months, P = 0.006, hazard ratio [HR] = 0.54, 95% confidence interval [CI]: [0.38–0.77]; OS: 46.4 months vs. 39.6 months, HR = 0.51, 95% CI = [0.31–0.84], P = 0.008). Conclusion: Patients with left-sided nonmetastatic tumors or metastatic tumors that could undergo curative surgery had higher DFS and OS. Among the patients who did not undergo curative surgery, and were treated with chemotherapy alone, PFS and OS were similar for tumors of both sides. With only chemotherapy without any targeted agents for the metastatic disease, there was no difference in survival with the side.