An aspirin a day cuts the risk of ovarian cancer in women most likely to develop the disease, according to new research.

It could protect those with a family history of the disease and carriers of the ‘Angelina Jolie gene,' say scientists.

The painkiller is believed to block triggering proteins. It also douses inflammation, which plays a key role in ovarian cancer—the most fatal gynecologic cancer.

"Most known risk factors of ovarian cancer—such as family history, mutations in the BRCA1 and 2 genes, and endometriosis—can't be modified," said lead author Dr. Britton Trabert, of the University of Utah.

The US team described the findings as "promising." It is an "actionable step" that vulnerable individuals may take.

Daily, or almost daily, aspirin use was associated with a 13% reduction in ovarian cancer risk and they found that aspirin benefitted most subgroups.

"Importantly, this research provides further evidence that ovarian cancer chemo-prevention with frequent aspirin use could benefit people in higher-risk subgroups," Dr. Trabert added.

Four years ago, a Harvard University analysis of more than 200,000 women found a daily low dose 75mg pill slashed case rates of the cancer by about a quarter. But individual studies have not been able to look at whether the drug benefits those with a higher risk of disease.

The Utah team pooled data from 17 studies, nine prospective cohort studies from the Ovarian Cancer Cohort Consortium, and eight case control studies from the Ovarian Cancer Association Consortium that included more than 8,300 cases.

"This gave us a more detailed and accurate look than if we used published data."

They were defined by specific risk factors like family history of breast or ovarian cancer, endometriosis where womb tissue grows around the ovaries, obesity, pregnancy, oral contraceptive use, and sterilization where the fallopian tubes are tied.

"Aspirin use has been linked with major adverse events, including internal bleeding and stroke," says Trabert. "Since aspirin helped people who had two or more risk factors, we hope patients and clinicians can use this research to have an informed conversation when it comes to potential preventive measures."

She earned a Department of Defense Investigator-Initiated Research Award for work on aspirin use and lower ovarian cancer rates. Ovarian cancer is known as ‘the silent killer' because there are few distinct symptoms until it is advanced.

Currently around a third of women are diagnosed early, and nine-in-10 women with early-stage disease survive. It drops to just one in ten if picked up late—one of the highest death rates of all cancers.

Aspirin has been used as a painkiller for thousands of years, since the Ancient Egyptians found an extract of willow bark helped mothers cope with child birth. But in recent years scientists have found the cheap drug has many more applications. It is commonly prescribed by doctors in lower doses to prevent heart problems, because it stops platelets in the blood clumping together to form clots.

But, low dose aspirin has also been found to significantly reduce the risk of bowel cancer—as well as skin, colon, lung and prostate cancer.

Aspirin is a blood thinner. It comes with a risk of internal bleeding – particularly among people with certain conditions such as an abnormal heart rhythm. In can cause stomach bleeds and ulcers that may require hospital treatment, and in rare instances a stroke or a life-threatening hemorrhage. So, individuals should consult their health care providers before beginning new medication to balance any potential risks with these potential benefits.

The study was published in the Journal of Clinical Oncology.