A Boston-based team, led by Dr Bin Ye and Dr Daniel Cramer at the Brigham and Women's Hospital, studied a population of women that included 600 ovarian cancer cases and 640 healthy, matched controls.
Women who took gingko supplements for six months or longer were shown to have a 60 per cent lower risk for ovarian cancer, the scientists told those attending the American Association for Cancer Research's annual Frontiers in Cancer Prevention Research meeting in Baltimore last week.
Ye and his colleagues observed that gingko, echinacea, St John's Wort, ginseng, and chondroitin were all commonly used by the study participants. But an analysis of the data showed that gingko was the only herb linked to ovarian cancer prevention.
The preventive effect was more pronounced in women with non-muncious ovarian cancers, with data showing that gingko may reduce the risk of this type of ovarian cancer by 65-70 per cent.
After further work in the laboratory, the researchers found evidence that ginkgolide A and B - terpene compounds - are the most active components contributing to this protective effect.
Additional lab tests supported the earlier epidemiological findings - a low dosage of ginkgolide caused ovarian cancer cells to stop growing, and researchers also observed significant cell cycle blockage in non-mucinous ovarian cancer cells. Ginkgolides appeared to be less effective against the mucinous type of ovarian cancer cells.
"While the detailed mechanism of ginkgo action on ovarian cancer cells is not yet well understood, from the existing literature it is most likely that gingko and ginkgolides are involved in anti-inflammation and anti-angiogenesis processes via many extra- and intra-cellular signal pathways," said Ye.
"In the future, these findings could potentially offer a new strategy for ovarian cancer prevention and therapy, using the active forms of ginkgolides."
Ovarian cancer is the most deadly of all gynecological cancers. Dubbed a 'silent killer' because most cases are discovered only in very advanced stages, it affects more than 1,000 women a year in the UK alone.