Deaths from ovarian cancer fell worldwide between 2002 and 2012 and are predicted to continue to decline in the US, European Union (EU) and, though to a smaller degree, in Japan by 2020, researchers said.
The main reason is the use of oral contraceptives and the long-term protection against ovarian cancer that they provide, said researchers, led by Professor Carlo La Vecchia from the University of Milan in Italy.
The decline in hormone replacement therapy (HRT) to manage menopausal symptoms and better diagnosis and treatment may also play a role, they said.
In the US the decline was even greater, with a 16 per cent drop in death rates from 5.76 per 100,000 in 2002 to 4.85 in 2012.
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In Canada ovarian cancer death rates decreased over the same period by nearly 8 per cent from 5.42 to 4.95. In Japan, which has had a lower rate of ovarian cancer deaths than many other countries, the death rate fell by 2 per cent from 3.3 to 3.28 per 100,000, the study found.
However, the pattern of decreases was inconsistent in some areas of the world, for instance in Latin American countries and in Europe, researchers said.
In European, the percentage decrease ranged from 0.6 per cent in Hungary to over 28 per cent in Estonia, while Bulgaria was the only European country to show an apparent increase.
In the UK, there was a 22 per cent decrease in death rates, which fell from 7.5 to 5.9 per 100,000 women. Other EU countries that had large decreases included Austria (18 per cent), Denmark (24 per cent) and Sweden (24 per cent).
"The large variations in death rates between European countries have reduced since the 1990s when there was a threefold variation across Europe from 3.6 per 100,000 in Portugal to 9.3 in Denmark," La Vecchia said.
"This is likely to be due to more uniform use of oral contraceptives across the continent, as well as reproductive factors, such as how many children a woman has," said La Vecchia.