Ovarian cancer is a type of cancer that develops in the tissue of the ovaries, which are the female reproductive glands that produce the egg. Although ovarian cancer risk is relatively low, affecting a mere 1.6% of the female population, it is one of the most fatal female-related cancers and it claims the lives of 2 out of every 3 women who are diagnosed with it.
Unfortunately, scientists have been unable to pinpoint the precise cause of ovarian cancer development, and most purported ovarian cancer risk factors are based on mere speculation. This lack of understanding, inspired scientists at the Cancer Epidemiology Unit (at Oxford University) to set out on a mission to better understand the factors that may contribute to ovarian cancer development.
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In attempt to identify ovarian cancer causes, the Oxford researchers analyzed patient data from 47 epidemiological studies. There is a surprising lack of research pertaining to ovarian cancer, and the Oxford scientist studied virtually all of the data available worldwide, which included over 25,000 women with ovarian cancer and 80,000 women without it. According to the study, which was published in PLoS Medicine Journal, taller women have a dramatically increased ovarian cancer risk. In fact, for every 5 cm increase in height, there was a corresponding 7% increased risk for ovarian cancer development. For instance, a 170 cm-tall woman would have a 14% higher risk of ovarian cancer development, than a women who was 160 cm.
Another surprising revelation was made during this meta-analysis—there was a positive correlation between a woman’s body mass index (BMI) and her ovarian cancer risk. BMI is a measurement of body fat that is based on a division of weight and height, and according to the study, for every 5 kg/m2 rise in BMI there was a corresponding 10% increase in relative ovarian cancer risk. Interestingly, woman with higher BMIs who had taken, or were on hormone replacement therapy (HRT) did not experience an increased risk for ovarian cancer. This finding was constructive because unlike height, weight is something that we can actively control. According to Sarah Williams, of Cancer Research UK, which funded the Oxford Study: “Women can reduce their risk of this (ovarian cancer) and many other diseases by keeping to a healthy weight. For women trying to lose weight, the best method is to eat healthily, eat smaller amounts and be more physically active.”
The researchers do not yet know how height and weight are related to ovarian cancer risk and they propose that there are a number of possible explanations. Dr. Gillian Reeves, one of the lead researchers of the Oxford study, theorizes that the association may be caused by biological factors related to height—such as an increased number of total cells being at risk for turning cancerous, or perhaps an increased level of insulin like growth factor (IGF-1), which has been found to increase both prostate and breast cancer risk. With regards to BMI and ovarian risk, it is possible that an increase in oestrogen levels caused by excess fat is a contributing factor. More research needs to be done to determine the cause of these associations, however, Dr. Reeves is optimistic that these newfound correlations will help scientists to better understand how and why ovarian cancer develops and thereby develop methods to reduce its prevalence.