Deaths from ovarian cancer fell significantly in Western countries from 2002 to 2012 and should continue declining largely thanks to widespread contraceptive pill use, researchers said.
Deaths fell 16 percent in the United States, 10 percent in the 28 European Union nations excluding Cyprus, for which there was no data, and eight percent in Canada.
In Japan, which has a lower ovarian cancer rate than many other countries, the death rate fell two percent, said a study published in the Annals of Oncology.
In Australia and New Zealand, deaths declined 12 percent from 2002 to 2011 – the most recent year for which data was available.
"The main reason for the favourable trends is the use of oral contraceptives," the authors wrote.
"The falls were greater in young and middle-aged women than in the elderly, and earlier and larger in the USA, the UK and northern Europe," they said.
"These are the countries where oral contraceptives (OCs) – which have a long-term protective effect on ovarian cancer risk – were introduced earlier and used more frequently."
HRT increases risk
A decline in hormone replacement therapy (HRT) to manage menopausal symptoms, as well as better cancer diagnosis and treatment, may also have played a role.
HRT, which uses oestrogen or progestogen to ease menopausal symptoms such as hot flushes, vaginal dryness and a low sex drive, is thought to increase the risk of ovarian cancer – by as much as 40 percent according to a 2015 study.
The Pill, on the other hand, is generally accepted to protect against the disease, dubbed a "silent killer" as it is often spotted too late.
Other research, though, has linked the contraceptive to an elevated risk of cancer of the breast, as well as heart attack and stroke.
Further declines predicted
The latest study, which had no numbers on Africa, said the pattern of decrease was inconsistent between countries.
Among European nations, the fall ranged from 0.6 percent in Hungary to over 28 percent in Estonia, with Bulgaria showing an increase.
In Latin America, deaths decreased in Argentina, Chile and Uruguay, but rose in Brazil, Colombia, Cuba, Mexico and Venezuela.
Based on data from the World Health Organisation, the team projected that ovary cancer deaths will decline by another 15 percent in the United States until 2020, and by 10 percent in the EU and Japan.