A new analysis of published and unpublished studies concludes that risk for ovarian cancer is associated with increasing height. It also finds that among women who have never used hormone therapy for the menopause, the risk for developing the disease is also tied to increasing body mass index, BMI, a measure of obesity.
The Collaborative Group on Epidemiological Studies of Ovarian Cancer, based at the University of Oxford in the UK, write about their findings in a paper published online in PLoS Medicine this week.
The findings are important because in high-income countries, height and BMI (a person’s weight in kilos divided by the square of their height in metres), have been increasing by about 1 cm and 1 kg/m2 respectively every decade.
Among its conclusions, the Collaborative Group, which comprises some 100 internationally based researchers in addition to the team at Oxford, suggests:
“If all other relevant factors had remained constant, then these increases in height and weight would be associated with a 3% increase in ovarian cancer incidence per decade.”
The authors decided to carry out the study because, as they explained in their background information, only about half the studies that have collected information on how women’s height and BMI might link to their risk of developing ovarian cancer have published results, plus, their findings are inconsistent.
So for their analysis they brought together all the worldwide data they could get their hands on, including published and unpublished results.
Altogether, their analysis included 47 epidemiological studies from 14 countries with individual patient data on a total of 25,157 women with ovarian cancer and 81,311 women without ovarian cancer.
The results showed there was a significant increase in risk for developing ovarian cancer for every 5 cm increase in height.
This link remained strong even when other factors were taken into account, such as age, whether the participant had reached menopause or not, education, smoking status, alcohol consumption, use of oral contraception, use of menopausal hormone therapy, and having close relatives with ovarian or breast cancer.
However, the researchers found that for BMI, the risk depended on whether women had ever taken menopausal hormone therapy, and not on 11 other factors examined.
The results showed that for every 5-point increase in BMI, the risk for ovarian cancer was 10% higher in women who had never taken menopausal hormone therapy:this was not the case for women who had previously taken the therapy.
Cancer Research UK funded the study, but played no part in designing, carrying out, or publishing it.
Ovarian cancer is the fifth leading cause of cancer death in women. It is often referred to as the “silent killer”, because unfortunately the symptoms, such as abdominal pain and swelling, do not emerge until the disease has reached a late stage.
Fewer than one third of ovarian cancers are detected before the cancer has spread beyond the ovaries, considerably reducing the odds that treatment will be successful.
Increasing age, not having used oral contraceptives, having fewer children, and use of menopausal hormone therapy are recognized risk factors for increasing the chance of developing the disease, with the first two having the biggest impact.
Written by Catharine Paddock PhD