Information from 17,641 colon cancer patients in the German Colon/Rectum Cancer Study Group found that people with cancers on the right side of the colon were older, had more chronic illness, and were more likely to be women.  There were significantly more deaths in this group.

While the rate of metastastic cancer spread was similar for both right and left sided tumors, spread to the liver or lungs was more common in the left-sided cancers and peritoneal carcinomatosis from tumors on the right.

Right-sided tumors were more often poorly differentiated and found in nearby lymph nodes (stage III.)

Even after adjusting for risk factors, survival was worse for cancers on the right side.

Right-sided tumors (proximal) included those in the the ascending and transverse colon, while the left side includes the descending and sigmoid colon nearest to the rectum (distal).

Frank Benedix, MD and the team from the Colon/Rectum Carcinomas Study Group concluded,

We found that right- and left-sided colon cancers are significantly different regarding epidemiological, clinical, and histological parameters. Patients with right-sided colon cancers have a worse prognosis. These discrepancies may be caused by genetic differences that account for distinct carcinogenesis and biological behavior. The impact of these findings on screening and therapy remains to be defined.

SOURCE: Benedix et al., Diseases of the Colon and Rectum, Volume 53, Issue 1, pp 57-64, January 2009.

Image courtesy of the National Cancer Institute Visuals Online.