Right Sided Colon Cancer as a Distinct Histopathological Subtype with Reduced Prognosis

Abstract

Background/Aims: Recent data suggest that tumors of the right and left colon should be distinguished as they differ in clinical and molecular characteristics. Methods: A total of 1,319 patients who underwent surgical resection for colon cancer (CC) were investigated. Tumors between the ileocecal valve and the hepatic flexure were classified as right CC (RCC), tumors between the splenic flexure and the rectum as left CC (LCC). Results: RCC revealed a higher cause-specific mortality risk (hazard ratio 1.36, 95% CI 1.10-1.68, p = 0.005) and lower 5-year cause-specific (RCC 64.9%, 95% CI 60.4-69.4, LCC 70.7%, 95% CI 67.2-74.2, p = 0.032) and disease-free (RCC 56.0%, 95% CI 51.5-60.5, LCC 59.9%, 95% CI 56.2-63.6, p = 0.025) survival rates. RCCs were more often microsatellite instable (RCC 37.2%, LCC 13.0%, p < 0.001) and more often showed KRAS (RCC 42.5%, LCC 18.9%, p = 0.001) and BRAF mutations (RCC 26.6%, LCC 3.2%, p < 0.001). Conclusion: RCC and LCC differ significantly regarding clinical, histopathological and molecular genetic features and can be considered as distinct entities. The reduced prognosis of RCC may be caused by higher rates of microsatellite instability, KRAS and BRAF mutations.

Clinico-pathological and oncological differences between right and left-sided colon cancer (stages I-III): analysis of 950 cases

“…In this series, right-sided colon cancer was significantly more frequent in women and in older patients than left-sided colon cancer, a finding which is consistent with other recent series (27,28). The ASA stages and the predictive POSSUM and P-POSSUM indices were similar to other series and in line with most studies.…”

“…Tumors of the right colon exhibited a higher incidence of the mucinous and signet ring cell phenotype, and were larger and more undifferentiated, which is consistent with findings from previous studies (27,32). The incidence of PNI and LVI was similar to that reported by other studies (33) and there were no significant differences between the two groups.…”

Prognostic Implication of KRAS Status after Hepatectomy for Colorectal Liver Metastases Varies According to Primary Colorectal Tumor Location

“…Specifically, several studies have noted that right-sided (RS) versus left-sided (LS) CRC differ in incidence, pathogenesis, genetic susceptibility to neoplastic degeneration, and oncologic outcomes. [14][15][16][17][18][19] Furthermore, these differences in molecular features and prognostic characteristics of the primary lesion may be maintained in the metastatic lesions. 20 For example, two studies recently reported different treatment outcomes for patients undergoing chemotherapy for metastatic CRC according to primary CRC site and KRAS status.…”

Outcomes of stage IV patients with colorectal cancer treated in a single institution: What is the key to the long-term survival?

“…The outcome of right-sided cancer has been reported to be worse than that of the left-sided disease [23][24][25][26] . Ishihara et al reported that a right-sided primary tumor was detected to be a worse prognostic factor in stage IV CRC 27) .…”