April 3, 2012

expert reaction to new research into height and weight as risk factors for ovarian cancer

A study in the journal PLoS Medicine suggested that increasing height and increased body mass index are risk factors for developing ovarian cancer.

Dr Paul Pharoah, Reader in Cancer Epidemiology, University of Cambridge, said:

“There are good data to show that both height and weight are associated with risk of several different cancers, but the evidence relating height and weight to the risk of ovarian cancer has been somewhat inconsistent.

“The study reported in PLoS Medicine has come from a well-established multi-centre collaboration. The data collation and analysis are fundamentally sound and the conclusions of the study are robust. The key findings are that (1) taller women have a slightly higher risk of developing epithelial ovarian cancer, and (2) that increasing body mass index is also associated with a slight increase in the risk of epithelial ovarian cancer in women who have never used hormone replacement therapy.

“In the press release it is stated that “. . .the researchers found a significant increase in the risk . . . “. While the association between height/body mass index and ovarian cancer is highly statistically significant, the magnitude of the increase is small. In other words the increase is not really of any significance to individual women.

“To illustrate:

“If we compare a woman who is 5′ 0″ tall with a woman who is 5′ 6” 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.

“These are not risk differences that could be considered significant to the individual. There are many other good reasons for maintaining a healthy body weight!”

‘Ovarian Cancer and Body Size: Individual Participant Meta-Analysis Including 25,157 Women with Ovarian Cancer from 47 Epidemiological Studies’ by the Collaborative Group on Epidemiological Studies of Ovarian Cancer, published in PLoS Medicine on Tuesday 3 April 2012.