Major Study Shows Aspirin Can Cut Polyp Return In Gi Cancer Patients


NewsRx.com


March 20, 2003

Patients who have had colorectal cancer may reduce their risk of suffering a
recurrence by taking an aspirin daily, according to a new study conducted by a
University of North Carolina at Chapel Hill physician and colleagues around the
United States.

The study showed that subjects who took 325 mg of aspirin each day had a 35%
lower risk of developing polyps in their colons during the period examined than
did patients who received an inactive placebo. Polyps are considered precursors
to most colorectal cancers. A report on the findings appears in the March 6,
2003, issue of the New England Journal of Medicine. More than 100 medical
centers and clinics throughout the United States participated in the study.

"From both animal research and observational studies, we've recognized for a
long time that aspirin might decrease the risk of colon cancer," said Dr. Robert
S. Sandler, the study's principal investigator. "To find out whether aspirin
really worked, we needed a randomized trial where we could compare aspirin with
a placebo. With the help of a large consortium of hospitals and a large number
of patients, that's what we've done. "

Sandler, professor of medicine and epidemiology at the UNC schools of medicine
and public health, also is chief of the division of digestive diseases and
nutrition and director of UNC's Center for Gastrointestinal Biology and Disease.

The double-blind study involved randomly assigning half of the 635 patients who
previously suffered colorectal cancer to an aspirin treatment group and the
other half to the placebo group, he said. He and colleagues gathered data,
determined the percentage of patients with recurrent polyps and, after adjusting
for age, sex, cancer stage and the timing of colonoscopies, analyzed how
patients fared in relation to which of the two groups they were in.

Doctors found that among the 517 patients who had at least one colonoscopy over
the previous year or so, 17% of those in the treatment group had one or more
polyps compared to 27% of those in the other group.

"Also, we found that the average number of polyps was lower in the aspirin
group, and aspirin delayed the appearance of polyps and slowed their
development," Sander said. "The fact that each of these measures went in the
same direction supports the idea that this is a real effect, and it's not simply
coincidence."

For ethical reasons, and so that doctors and patients could learn about the
findings sooner, an independent data and safety monitoring board ended the study
early when it found statistically significant differences in the recurrence of
polyps during an interim analysis.

"These findings are good news and encouraging, but they don't mean that people
can assume they can protect themselves completely from colon cancer," the UNC
physician said. "We view aspirin or drugs like aspirin as being an adjunct to
colonoscopy, during which we can remove any polyps that aspirin failed to
prevent."

Patients in the new study already had had cancer, and the risk of colon cancer
in an average person would be lower, Sandler said. As a result, the protective
effect of aspirin might be lower in other people as well. Somewhat fewer than 5%
of polyps become cancerous, and individuals who have had one or more of the
unhealthy growths are about three times more likely to develop a colon cancer
than those who have had none.

"One good thing about these results is that they demonstrate you can change the
natural history of polyps by intervening," he said. "Eventually, we might be
able to find other chemicals, nutrients or vitamins that we could use that would
do the same thing."

Sandler was a coauthor of a related investigation appearing in the same issue of
the journal that showed a similar protective effect of aspirin, although at a
lower dose comparable to baby aspirin. The 1084 patients in that study had
polyps previously diagnosed but not colorectal cancer. Dr. John A. Baron of
Dartmouth Medical School was principal investigator for that research.

In an article accompanying the two studies, Dr. Thomas F. Imperiale of Indiana
University said determining whether aspirin has a role in preventing colon
cancer must await the results of studies of whether it can be used to decrease
screening or surveillance.

"Although aspirin may be of some benefit in preventing colorectal cancer, it
cannot yet be recommended for this indication and is not a substitute for
screening and surveillance," Imperiale wrote. "Nevertheless, the(se)
well-conducted trials ... provide proof of the principle that aspirin moderately
reduces the risk of recurrent colorectal neoplasia and provide support for the
assumptions and probabilities that have been used in published analyses of
cost-effectiveness."

An earlier study suggested that calcium can prevent polyp formation to about the
same extent that aspirin can, Sandler said. Before people begin taking aspirin,
they should discuss the matter with their doctors.

"We recommend that people over age 50 undergo screening for colon cancer," he
said. "If they are screened with colonoscopy, and it is normal, they do not need
the exam again for 10 years. There are other screening tests that are also
effective, including fecal occult blood testing every year and sigmoidoscopy,
which views half as much of the colon, every 5 years."

Coauthors of the first report are Dr. Susan Halabi and Susan Budinger of Duke
University Medical Center, Baron and Dr. J. Marc Pipas of Dartmouth, Dr. Electra
Paskett of Wake Forest University School of Medicine, Dr. Roger Keresztes of
Weill Medical College of Cornell University and Dr. Nicholas Petrelli of Roswell
Park Cancer Institute in Buffalo. Others are Drs. Daniel D. Karp of the Eastern
Cooperative Oncology Group, Charles L. Loprinzi of the Mayo Clinic, Gideon
Steinbach of M.D. Anderson Cancer Center in Houston and Richard Schilsky of the
University of Chicago. This article was prepared by Cancer Weekly editors from
staff and other reports.


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