Cholecystectomy modestly raises colon cancer risk
Last Updated: August 29, 2005



NEW YORK (Reuters Health) - Cholecystectomy modestly raises the risk
of colon but not rectal cancer in men and women, suggest results of a
population-based study conducted in the UK. The findings support
the "global view" of previous epidemiological studies on the link
between gallbladder removal and colon cancer, investigators note in
the August American Journal of Gastroenterology.


According to Drs. Theresa Shao and Yu-Xiao Yang from the University
of Pennsylvania School of Medicine in Philadelphia "lithogenic bile
could be the underlying mechanism."

"It is hypothesized," they explain, that increased mucosal exposure
to secondary bile acids and undigested fat following cholecystectomy
may lead to mucosal damage and subsequent cellular proliferation,
perhaps leading to cancer." The suggestion that cholecystectomy
raises the risk of colon but not rectal cancer "is consistent with
the bile acid exposure theory."

Drs. Shao and Yang used the UK General Practice Research Database to
assess the risk of colorectal cancer after cholecystectomy. Among
55,960 men and women who had the surgery, the incidence of colorectal
cancer was 119 per 100,000 person-years, modestly higher than the
incidence of 86 per 100,000 person-years among 574,668 patients who
did not have the surgery.

"Adjusting for various known and suspected risk factors for
colorectal cancer did not change this association," the investigators
note. The adjusted incidence rate ratio of colorectal cancer with
cholecystectomy was 1.32. The positive association was present for
colon cancer but not for rectal cancer, with adjusted rate ratios of
1.51 and 1.00, respectively.

Cholelithiasis also raised the risk of colon cancer to a similar
degree as cholecystectomy, which also supports the lithogenic bile
acid exposure theory.

The researchers caution, however, that "for an individual patient,
such a modest risk increase should weigh little in the decision to
undergo elective cholecystectomy."

"However, owing to the high prevalence of gallstone disease and
cholecystectomy in the general population, even an association of
relatively small magnitude could have important public health
implications," they write.

"Studies are needed," they conclude, "to determine whether it would
be cost-effective to implement a more stringent colon cancer
screening strategy in this patient population."