Taking hormone replacement therapy (HRT) for menopause could increase women's risk of developing ovarian cancer, even if it is only used for a few years.
The findings revealed that women who used HRT for short periods of time were about 40 percent more likely to develop ovarian cancer than women who never used the treatment, the Lancet reported.
"For women who take HRT for 5 years from around age 50, there will be about one extra ovarian cancer for every 1000 users and one extra ovarian cancer death for every [1,700] users," said study co-author Professor Sir Richard Peto from the University of Oxford.
To make their findings, the researchers looked at 52 epidemiological studies involving a total of 21,488 women with ovarian cancer from North America, Europe and Australia. They found that while the risk of ovarian cancer decreased over time after stopping treatment, women who used HRT for at least five years still had a somewhat increased risk a decade later.
HRT use decreased significantly about a decade ago, but has now leveled off with over six million women still using the treatments in the U.K. and U.S.
"The definite risk of ovarian cancer even with less than 5 years of HRT is directly relevant to today's patterns of use--with most women now taking HRT for only a few years--and has implications for current efforts to revise UK and worldwide guidelines," said study co-author Professor Dame Valerie Beral, also from the University of Oxford.
The findings were published in a recent edition of the journal the Lancet and was funded by the Medical Research Council and Cancer Research U.K.
