Talking About Ovarian Cancer Prevention with Elisa Bandera
AICR's new report on ovarian cancer found that – for the first time – obesity links to increased risk. The Continuous Update Project (CUP) report analyzed the global research on diet, activity, and weight to the risk of ovarian cancer. Here, Elisa Bandera, MD, PhD, a panelist on the CUP report and epidemiologist at the Rutgers Cancer Institute of New Jersey, talks about the report’s findings and what it means.
Q: The report uses increments of BMI to measure risk. Can you talk about the findings?
A: In an analysis of the studies, we did find there was a 6 percent increase risk for every 5 increments in BMI. But not everyone who was overweight was at increased risk. We saw the increased risk started at the highest categories of overweight - specifically at a BMI of 28.4. [Obesity starts at a 30 BMI.] The main point is that it is obese women who have the highest risk.
Q: This CUP report builds on the 2007 report, how has the research grown since then?
A: For this report we are focusing on prospective studies, which are considered of better quality because in this type of studies dietary exposures or body weight are evaluated before the disease develops, and therefore cannot influence recall of habits. There are many more studies now - for weight we had 26 studies compared to 7 in the last report. For some dietary factors we still don't have enough and the evidence for most of them is still insufficient.
Q: Do the report findings relate to reducing risk of recurrence for survivors?
A: The studies included in the report evaluated risk of developing ovarian cancer, and not the impact of obesity on recurrence. However, two of the studies included in the report found obese women had elevated ovarian cancer mortality.
Q: What are some possible reasons why too much body fat increases risk?
A: Obesity is associated with a hormonal imbalance and high levels of many of these hormones, such as estrogen and insulin, affect cancer development. Obesity also leads to chronic systemic inflammation, which is strongly linked to increased cancer risk. Inflammation especially has been shown to be a major factor for ovarian cancer risk and survival. We know, for example, obese women have high levels of C-reactive protein [a marker for inflammation] and that links to reduced survival.
"This link with obesity reinforces the message that maintaining a healthy weight is important for cancer prevention."
Q: Obesity is one risk factor, what are some others that can reduce ovarian cancer risk?
A: The strongest factors that have been associated with reduced risk are oral contraceptive use, tubal ligation and having children. Breastfeeding has been considered to be a protective factor, but there were only three prospective studies evaluating the association with ovarian cancer. The evidence was found to be limited, but suggestive of having a beneficial effect.
Q: What is important here for women to know?
A: Many of these known factors are difficult to control, particularly at an older age when we typically start to worry about cancer. This finding with weight is good news, because this is a factor that women can do something about. This link with obesity reinforces the message that maintaining a healthy weight is important for cancer prevention. We already knew a healthy weight reduces the risk of several cancers, and now we can add ovarian cancer to the list.