Postdiagnosis Use of Aspirin Reduces Risk of Dying from Colorectal Cancer

The researchers from Massachusetts General Hospital (MGH), Dana-Farber Cancer Institute, and Brigham and Women's Hospital, all based in Boston (MA, USA), also found that the aspirin-associated survival advantage was seen mainly in patients with tumors expressing the COX-2 (cyclooxygenase-2) enzyme, a characteristic of two-thirds of colorectal tumors.

"While previous studies by our group and others showed that aspirin and other non-steroidal anti-inflammatory drugs reduce the risk of developing colorectal cancer, this study is the among the first to show that aspirin can also improve survival in patients who have already been diagnosed with colorectal cancers. Moreover, the benefit appeared to be especially strong among patients with cancers that express COX-2,” stated Andrew Chan, M.D., MPH, of the MGH gastrointestinal unit, the study's lead author. "This is an important first step toward developing targeted approaches to improving patient outcomes.”

Many earlier studies have shown that regular use of aspirin and other non-steroidal antiinflammatory drugs reduces the risk of developing colorectal cancer. In 2007, the same MGH/DFCI investigators found that the benefit only applied to tumors overexpressing COX-2, an enzyme believed to enhance tumor growth and known to be inhibited by aspirin and related drugs. To evaluate their hypotheses that aspirin would also improve the survival of patients diagnosed with colorectal cancer, again through its inhibition of COX-2, the researchers compiled data from two ongoing prospective research studies--the Nurses' Health Study (NHS) and the Health Professionals' Follow-Up Study (HPFS). Both studies collect comprehensive health information on their participants every two years; data are then analyzed for associations between factors such as medication use and the incidence of several diseases.

The current study focused on 1,279 study participants who were diagnosed with stage I, II, or III colorectal cancer during their participation in the studies for whom data were available on aspirin use before and after diagnosis. Tumor samples available from 459 participants were analyzed for the expression of COX-2. Study results indicated that patients who regularly took aspirin after their diagnosis had a nearly 30% lower risk of dying of colorectal cancer during an average of 11 years after diagnosis than those that did not use aspirin. The benefit was especially strong among patients who began using aspirin after diagnosis. In contrast, patients who were aspirin users before diagnosis did not appear to benefit as much from continuing aspirin use after diagnosis. As expected, the survival benefit appeared restricted to patients with COX-2-positive tumors.

"We believe our results could lead to improvements in the therapy of patient with colon cancer,” stated Charles Fuchs, M.D., MPH, of Dana-Farber, the study's senior author. "We're now following up this observational study with a randomized trial to evaluate adding the COX-2 inhibitor celecoxib, which is less likely to have the gastrointestinal side effects of aspirin, to standard chemotherapy.”

Dr. Fuchs is an associate professor of medicine at Harvard Medical School (Boston, MA, USA), where Dr. Chan is an assistant professor of medicine. Study coauthor Shuji Ogino, M.D., Ph.D., is an associate professor of pathology at Brigham and Women's Hospital.

Related Links:
Massachusetts General Hospital
Dana-Farber Cancer Institute
Brigham and Women's Hospital