Aspirin not a cost effective substitute for colorectal cancer screening

Some animal studies have shown that aspirin and other nonsteroidal
anti-inflammatory drugs (NSAIDs) have an anti-tumor effect in the colon. Also,
some studies in people suggest that these drugs may decrease the risk of
colorectal cancer.

However, researchers at UCSF and the University of Michigan have determined in
a recent study that aspirin is not a cost-effective addition to the national
strategy for reducing death from colorectal cancer.

“While aspirin may be of some benefit in colorectal cancer prevention, it
should not replace known screening methods,” said Uri Ladabaum, MD, MS, UCSF
assistant professor of gastroenterology and lead author of the study, which
appears in the November 6 issue of the Annals of Internal Medicine. “In
addition, in terms of cost and benefits, it does not make sense for patients
already getting regular screening to take aspirin to prevent colorectal cancer.
Screening is highly cost-effective and remains so, even in patients already
taking aspirin for other reasons like arthritis or prevention of heart
disease.”

Screening tests, including flexible sigmoidoscopy every five years and yearly
fecal occult blood testing (FS/FOBT) or screening colonoscopy every ten years
(COLO), remain the best strategies for preventing death from colorectal cancer
in men and women, according to the researchers.

Though colorectal cancer screening is highly effective, less than half of the
population seek it, said Mark Fendrick, MD, associate professor of medicine at
the University of Michigan and a co-investigator on the study. He explained
that increasing adherence to screening should be the primary goal on the
national agenda for preventing death from colorectal cancer.

“Most colorectal cancers develop from benign growths in the colon called
polyps. Screening can detect polyps, and removing polyps can prevent a large
fraction of all colorectal cancers,” said Ladabaum. “In addition, screening can
detect cancers early, before any symptoms have developed. By the time symptoms
develop, it is often too late to treat the cancer successfully.”

Researchers constructed a computer simulation of the natural history of
colorectal cancer in patients at average risk for the disease. In the model,
investigators assumed aspirin could reduce colorectal cancer deaths by 30
percent. Aspirin actually increased costs and resulted in loss of life-years
when used as an adjunct to FS/BOBT. Under all circumstances, the complications
associated with aspirin (bleeding, perforated ulcer, and death) were an
important determinant of cost effectiveness, according to the researchers.

Aspirin cost $149, 161 per life-year gained as an adjunct to COLO. “This is
the amount of money that needs to be spent by a third party payer to cover
screening, aspirin, cancer care and the complications,” said Ladabaum. “In
general, interventions that society is willing to pay for are in the range of
$50,000 or less per life year gained.”

Screening fits within those parameters, he explained.  It cost less than
$25,000 per life-year gained and was more effective than aspirin alone. In
patients already taking aspirin, screening with FS/BOBT or COLO cost less than
$31,000 per life-year gained.

“This highlights the need to study safer chemo-prevention alternatives,” said
James Scheiman, MD, associate professor of medicine at the University of
Michigan and a co-investigator on the study. He added that cyclooxygenase-2
(COX-2) inhibitors may prove to be safer, but more costly.

The computer model estimated clinical and economic consequences of six
strategies: 1) no aspirin or screening, 2) FS/FOBT, 3) COLO, 4) aspirin alone
(ASA), 5) FS/FOBT and aspirin, 6) COLO and aspirin.

Beginning at 50 years of age, patients progressed through the model for 30
one-year cycles.  Principal disease states were defined as: normal, polyp,
cancer (localized, regional or disseminated), and deceased. Researchers assumed
that 90 percent of cancers develop from polyps and that cancer progresses from
localized to regional to disseminated.

Procedure costs were derived from Medicare fee schedules and included
professional fees and median procedure reimbursement. Researchers used the
wholesale cost of aspirin at the University of Michigan pharmacy. Costs for
cancer care of stage-specific colon cancer were taken from reports to the
National Cancer Institute. All costs were in 1998 dollars.

This study was funded by grants from the National Institutes of Health to the
University of Michigan and UC San Francisco.
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NOTE TO THE MEDIA: For access to video news release (shot at UCSF with Dr.

Ladabaum and a UCSF patient) feed times on November 5, 2001 are as follows:

9:00-9:30 a.m. (EST): Telestar 6, transponder 11, C-band.
Downlink Freq: 3920 (V)

2:00-2:30 p.m. (EST): Same coordinates

For those who need a hard copy, contact Maya Burghardt at On the Scene
Productions: 323-930-1030, [email protected]

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