SAN DIEGOIn anticipation of a phase II chemoprevention study,
researchers at the University of Texas M.D. Anderson Cancer Center
determined that low doses of aspirin work as well in suppressing
prostaglandin E2 (PGE2) as higher doses. Frank A. Sinicrope, MD,
presented the results at an American Gastroenterological Association
poster session held during the Digestive Disease Week conference.
Epidemiologic studies indicate that regular aspirin use is associated
with a significant reduction in colorectal cancer occurrence and
death. However, Dr. Sinicrope said, because of the
potential for GI toxicity associated with aspirin, we wanted to see
if lower doses would suppress prostaglandin production (believed to
be important in the development of colon polyps and cancer) to the
same degree as higher doses.
The researchers recruited 60 patients from an HMO who had a sporadic
colorectal adenoma within the past 5 years. They were randomized to
one of three daily aspirin doses81 mg, 325 mg, and 650
mgor a placebo for 28 days.
To verify compliance, plasma salicylate levels were examined, along
with pill counts and patient calendars. Of the 55 evaluable patients,
using salicylate levels, Dr. Sinicrope found that 91% of the patients
were compliant. Pill counts showed that more than 98% of the aspirin
doses were taken by all subjects, and self-reports were concordant
with pill counts.
The 81 mg of aspirin did just as good a job in significantly
suppressing PGE2 levels as the higher doses with no toxicity,
he reported. That means well be using that dose in an
upcoming phase II chemoprevention trial. It also means that a high
level of compliance can be expected in an at-risk population.
After the trial, Dr. Sinicrope sent a follow-up questionnaire to the
participants. Of the 43 subjects who returned the questionnaire, 19
(44%) said they had continued to take aspirin daily.
We wanted to figure out the prestudy factors associated with a
patients decision to continue to take aspirin daily, he
said. We learned that patients who reported taking vitamins and
minerals daily were significantly more likely to take aspirin, as
were those who expressed a desire to help future generations at
risk. A post-study query showed that motivators for
continued aspirin intake included a desire to lower their own risk of
cancer and study participation.