Taller women have a slightly higher risk of ovarian cancer, according to a review of studies.Obesity is also a risk factor among women who have never taken HRT, say international researchers.Previous studies have suggested a link, but there has been conflicting evidence.The latest research, published in the journal PLoS Medicine, analysed all worldwide data on the topic.It looked at 47 epidemiological studies in 14 countries, including about 25,000 women with ovarian cancer and more than 80,000 women without ovarian cancer.Lead researcher Prof Valerie Beral of the Oxford University Epidemiology Unit told the BBC: "By bringing together the worldwide evidence, it became clear that height is a risk factor."She said there was also a clear relationship between obesity and ovarian cancer in women who had never taken HRT."Ovarian cancer can clearly be added to the list [of cancers linked to obesity]," she added.Sarah Williams, health information officer at Cancer Research UK, said the study produced a clearer picture of the factors that could affect a woman's risk of developing ovarian cancer, and found that body size was important."Women can reduce their risk of this and many other diseases by keeping to a healthy weight," she said."For women trying to lose weight, the best method is to eat healthily, eat smaller amounts and be more physically active."Commenting on the study, Dr Paul Pharoah, reader in cancer epidemiology at the University of Cambridge, said the increase in risk was small."If we compare a woman who is 5ft tall with a woman who is 5ft 6in tall, there is a relative difference in ovarian cancer risk of 23%."But the absolute risk difference is small. The shorter woman will have a lifetime risk of about 16-in-a-1000 which increases to 20-in-a-1000 for the taller woman."A similar difference in absolute risk would be seen when comparing a slim woman with a body mass index of 20 to a slightly overweight woman with a body mass index of 30."