Are there two sides to colorectal cancer?
Article first published online: 16 AUG 2002
Copyright © 2002 Wiley-Liss, Inc.
International Journal of Cancer
Volume 101, Issue 5, pages 403–408, 10 October 2002
How to Cite
Iacopetta, B. (2002), Are there two sides to colorectal cancer?. Int. J. Cancer, 101: 403–408. doi: 10.1002/ijc.10635
- Issue published online: 3 SEP 2002
- Article first published online: 16 AUG 2002
- Manuscript Accepted: 11 JUL 2002
- Manuscript Received: 2 MAY 2002
- Cancer Foundation of Western Australia
- colon cancer;
- rectal cancer;
- proximal colon;
- distal colon;
- molecular profile;
Colorectal carcinomas (CRC) that arise proximal (right) or distal (left) to the splenic flexure exhibit differences in incidence according to geographic region, age and gender. Together with observations that tumours in the hereditary cancer syndromes HNPCC and FAP occur predominantly in the right and left colon, respectively, the existence of 2 categories of CRC based on site of origin in the large bowel was proposed more than a decade ago. Differences between normal right and left colonic segments that could favour progression through different tumourigenic pathways are summarized in this review. Accumulating evidence suggests that the risk of CRC conferred by various environmental and genetic factors is different for proximal and distal tumours. Right- and left-sided tumours also exhibit different sensitivities to fluorouracil-based chemotherapy. Such differences are probably related to the molecular characteristics of the tumours, with the microsatellite instability and CpG island methylator phenotypes being associated with right-sided tumours and chromosomal instability with left-sided tumours. Future molecular-based classification systems for CRC that rely upon distinctive gene expression patterns may allow a clearer discrimination of subgroups than that provided by tumour site alone. Until then however, the existence of 2 broadly different groups of cancer defined by site of origin in the colon should be considered in the design of future epidemiologic studies as well as in the design of new clinical trials aimed at testing novel adjuvant therapies. © 2002 Wiley-Liss, Inc.