An everyday pain reliever could make women more likely to get ovarian cancer.
Both sets of hazard ratios reflected multivariable adjustment that included such factors as age, menopausal status, parity, and family history of cancer. The results were published October 4 in JAMA Oncology.
Senior study author Dr. Andrew Chan pointed out that "aspirin use is already recommended for prevention of heart disease and colorectal cancer in certain USA adults". While several previous studies have sought to determine if aspirin and other common anti-inflammatory medications influence the risk of ovarian cancer, the findings have been inconsistent.
Seewaldt said the two studies "have the power to start to change clinical practice", but cautioned that the risk-benefit ratio must be considered when recommending aspirin.
"The potential benefits of aspirin must be weighed against the risk of bleeding, particularly in individuals with chronic liver disease", said Seewaldt.
Aspirin is now commonly used long-term to help prevent further heart attacks, ischemic strokes and blood clots in people at high risk.
"What really differentiated this study from prior work was that we were able to analyze low-dose aspirin separately from standard-dose aspirin", Barnard said in a statement.
The findings indicate that recommendations made by the U.S. Preventive Services Task Force in 2016 advising older adults who are at an elevated risk of cardiovascular disease to take low-dose aspirin are unlikely to increase the risk of ovarian cancer, the researchers said.
The team found a 23 percent lower risk of ovarian cancer in women who reported that they had recently been frequently taking up to 100 milligrams of aspirin, compared with women who had taken none.
While HCC is relatively rare, its incidence in the USA has increased over the past 40 years, and mortality rates have accelerated faster than those of any other cancer.
Aspirin is thought to lower cancer risk by reducing inflammation.
The study also found that long-term heavy use of non-aspirin non-steroidal anti-inflammatory drugs (NSAIDs) may be associated with an increased risk of ovarian cancer.
For the ovarian cancer study, researchers analyzed 93,664 women who were followed up from 1980 to 2014, and 111,834 followed from 1989 to 2015. Among the 205498 women in both cohorts, there were 1054 cases of ovarian cancer recorded over the course of the study period, which was up to 30 years.
"Regular use of aspirin led to significantly lower risk of developing HCC, compared to infrequent or no aspirin use, and we also found that the risk declined progressively with increasing aspirin dose and duration of use", co-author Tracey Simon, MD, of Massachusetts General Hospital in Boston, said in a statement. Just as the risk reduction increased with longer duration of aspirin use, it also decreased if aspirin was discontinued, disappearing by eight years after aspirin use was halted.
Ovarian cancer is the fifth most common cause of cancer-related deaths among women in the USA, and growing evidence suggests a role for inflammation in the development of the disease, the authors write.