US researchers found that patients who regularly took aspirin after being diagnosed with colorectal cancer had a reduced risk of dying from the
disease, and the benefit was greater for patients with a type of colon cancer where the tumors overexpress the COX-2 enzyme, which happens in
around two thirds of cases. However, more work needs to be done to confirm the result before applying it to patient care, said the
The study was the work of investigators from Massachusetts General Hospital (MGH), Dana-Farber Cancer Institute and Brigham and Women's Hospital and is published online in the 12 August issue of the Journal of the American Medical Association (JAMA).
Lead author Dr Andrew Chan, of the MGH Gastrointestinal Unit told the press that:
"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," he added, stating that:
"This is an important first step toward developing targeted approaches to improving patient outcomes."
Chan and colleagues brought together data from two ongoing prospective studies, the Nurses Health Study (NHS) and the Health Professionals Follow-Up Study (HPFS), which capture detailed health information on their participants every two years. Researchers use the comprehensive data from these studies to look for links between various factors such as use of drugs and incidence of several diseases.
For this study, Chan and colleagues focused on the data from 1,279 study participants who were diagnosed with stage 1, 2 or 3 colorectal cancer during the period of the studies and for whom data on their use of aspirin before and diagnosis was available.
The results showed that:
- After a median follow up of 11.8 years, 193 (35 per cent) of the 549 participants who regularly used aspirin after being diagnosed with colorectal cancer had died, and of these deaths 81 (15 per cent) were from colorectal cancer.
- This compared with 287 total deaths (39 per cent) and 141 colorectal cancer-specific deaths (19 per cent) among 730 participants who did not use aspirin.
- Compared with those who did not use aspirin, participants who regularly used aspirin after diagnosis had a 29 per cent lower risk of dying from the disease and a 21 per cent lower risk of dying from any cause.
- Among 719 participants who did not use aspirin before diagnosis, those that started using aspirin after diagnosis had a 47 per cent lower rate of death from colorectal cancer compared with those who did not.
- Tumor samples from 459 participants were tested for COX-2 expression.
- Among these, regular aspirin use after diagnosis was linked to a 71 per cent lower risk of dying from colorectal cancer for those participants whose tumors overexpressed COX-2, whereas aspirin use was not linked to lower risk among those whose primary tumors had weak or no expression of COX-2.
"Regular aspirin use after the diagnosis of colorectal cancer is associated with lower risk of colorectal cancer-specific and overall mortality, especially among individuals with tumors that overexpress COX-2."
Senior author Dr Charles Fuchs of of Dana-Farber said:
"We believe our results could lead to improvements in the therapy of patients with colon cancer."
"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."
"Aspirin Use and Survival After Diagnosis of Colorectal Cancer."
Andrew T. Chan; Shuji Ogino; Charles S. Fuchs.
Published online 12 August 2009.
Additional source: Massachusetts General Hospital.
Written by: Catharine Paddock, PhD