Colon cancer patients who took aspirin regularly fared better after surgery, reducing their risk of disease recurrence and death by half compared to non-users, researchers will report at the annual meeting of the American Society of Clinical Oncology.
While previous studies have shown that aspirin use provided a preventative benefit by lowering the risk of developing colon cancer and intestinal polyps, the new study is the largest to demonstrate that aspirin had a potential treatment benefit in people who have been diagnosed with colon cancer. Charles Fuchs, MD, MPH, of the Dana-Farber Cancer Institute in Boston, is lead author on the report by researchers from the Cancer and Leukemia Group B, a national clinical research group.
"Our data are intriguing because they showed that aspirin use notably reduced the risk of recurrence in patients with advanced colon cancer, but more research is needed before any treatment recommendations can be made about the regular use of aspirin," says Fuchs.
The findings emerged from a prospective study of 846 patients who were enrolled in a randomized trial of two chemotherapy regimens following surgery for colon cancer. They all had stage III disease that had spread to lymph nodes but not elsewhere in the body. The researchers interviewed the patients about medication use and lifestyle midway through their chemotherapy, and again six months after therapy was completed.
Regular aspirin use was reported by 75 patients (8.9 percent) in doses of 81 mg ("baby" aspirin) to 325 mg per day. A total of 41 patients (4.7 percent) reported using COX-2 inhibitor anti-inflammatory agents, Celebrex or Vioxx.
The researchers found, based on an average follow up of 2.7 years after the second interview, that regular aspirin users had a 55 percent lower risk of colon cancer recurrence and a 48 percent lower risk of death compared to non-users. The benefit of aspirin was independent of the dose, as long as the patient consistently took the painkiller throughout the follow-up period. Those who took Celebrex or Vioxx had a 53 percent reduction in recurrence risk.
The researchers also assessed the study participants' use of acetaminophen – to determine whether the benefits attributed to regular aspirin and COX-2 inhibitors had a non-specific analgesic effect – and found no recurrence or survival benefit.
Fuchs, who is also an associate professor of medicine at Harvard Medical School, says the next step is to conduct more research to confirm these findings and to determine the mechanism by which aspirin use produces treatment benefit. He adds that studies currently are underway to examine the addition of COX-2 inhibitors to chemotherapy in patients with advanced colon cancer.