Taking aspirin on a regular basis can reduce the risk of ovarian cancer.
However, the team discovered no links between "standard-dose" aspirin use (325 milligrams) and ovarian cancer risk.
There was a suggestion, though, that frequent heavy use of non-aspirin nonsteroidal anti-inflammatory drugs (NSAIDs) could be associated with a higher risk of developing ovarian cancer.
A paper on this study — which was led by the Harvard T.H. Chan School of Public Health in Boston, MA — is to appear in the JAMA Oncology journal.
"Our findings," explains lead study author Dr. Mollie E. Barnard, who worked on the study while she was at the Harvard T.H. Chan School of Public Health, "emphasize that research on aspirin use and cancer risk must consider aspirin dose."
'Few modifiable risk factors'
In terms of the number of women who die of cancer in the United States, ovarian cancer ranks fifth. In 2018, around 22,240 women will discover that they have the disease and 14,070 will die of it, according to the American Cancer Society (ACS).
In citing reasons for their investigation, Dr. Barnard and her colleagues note that there are "few modifiable risk factors" for ovarian cancer.
There is, however, increasing evidence that inflammation contributes to ovarian cancer.
This adds weight to the argument that anti-inflammatories including aspirin and non-aspirin NSAIDs can reduce ovarian cancer risk; but previous studies of their effects have given inconsistent results.
The investigators sought to address the confusion by running a robust study with "adequate power and sufficiently detailed exposure data to evaluate whether timing and patterns of analgesic use are associated with ovarian cancer risk."
The link was only to low-dose aspirin use
The study data came from a total of 205,498 women — 1,054 of whom developed ovarian cancer — who were followed in the Nurses' Health Study and Nurses' Health Study II.
The women had reported use of standard and low-dose aspirin, other NSAIDs, and acetaminophen. The self-reports gave details of timing, pattern, frequency, and duration of use, including numbers of tablets taken.
The analysis showed a link between "recent low-dose aspirin use" and a reduced risk of ovarian cancer, but there was no link for standard-dose use.
Longer-term use of low-dose aspirin, however, was not linked to further risk reduction.
There was a suggestion, however, that taking at least 10 tablets per week of non-aspirin NSAIDs such as naproxen and ibuprofen for several years could be tied to higher risk of ovarian cancer. The team notes that this needs to be confirmed with further research.
The authors note that they found "no clear associations for the use of acetaminophen."
"Our results also highlight the need for ongoing conversations between patients and their doctors on the risks and benefits of taking low-dose aspirin."
Dr. Mollie E. Barnard