Background: Colon cancer represents a major health concern worldwide and ranks as the second most common cause of cancer death. Nowadays, oncologists have strong evidence that colon cancer sidedness has a crucial effect on epidemiological, clinical, pathological, and molecular features of the patients, their response to treatment, and their survival outcomes. Based on these data, our study was conducted to evaluate the effect of primary tumor location in patients with metastatic colon cancer.
Patients and methods: This study is a prospective cohort study conducted among 140 patients with a proven diagnosis of metastatic colon cancer adenocarcinoma (70 with right-sided colon cancer and 70 with left-sided colon cancer) who received treatment at South Egypt Cancer Institute to compare between both groups as regards epidemiological, clinical, pathological, and molecular characteristics, response to first- and second-line treatment, and survival outcomes. Statistical analysis was done using SPSS program version 20. Difference was considered statistically significant at P-value < 0.05. Survival curves were conducted by using the Kaplan-Meier methods and were compared with the log-rank test.
Results: Metastatic Right-sided colon cancer (RCC) occurred at older age and affected more females versus metastatic left-sided colon cancer (LCC). Metastatic RCC was more commonly presented with anemia in contrast to metastatic LCC which was more frequently presented with lower gastrointestinal bleeding or change in bowel habits. More cases of mucinous differentiation and poor or undifferentiated morphology were observed among metastatic RCC patients who also had a more predilection for peritoneal metastases versus hepatic metastases which were more commonly detected among metastatic LCC patients. Wild type (non-mutated KRAS form) of colon cancer was more prevalent among metastatic LCC. Metastatic RCC patients showed a better overall response rate to first-line treatment with chemotherapy plus panitumumab. No significant differences in survival outcomes were found between metastatic RCC and LCC even in patients treated with chemotherapy plus panitumumab. Conclusion: Metastatic RCC and LCC have significant differences including epidemiology, histo-pathology, clinical presentation and behavior, molecular phenotyping, and response to treatment