Obesity Can Be a Risk Factor for Ovarian Cancer

Society places a good deal of pressure on women to maintain a certain weight and to look a certain way. Medically, avoiding obesity has its advantages, including decreased risk of diabetes, breast cancer, sleep apnea, and a host of other physical problems. Now, there in one more reason to maintain a healthy weight: the link between obese postmenopausal women and ovarian cancer.

A new study, to be published in the February 15th issue of the journal Cancer, found this recent link. Interestingly, obese women who have used hormone replacement therapy for the symptoms of menopause may not face this increased risk.

Dr. Jay Brooks, who is the chairman of hematology/oncology at Ochsner Health System in Baton Rouge, said, “This is another, very fine epidemiologic study that shows a relationship between obesity and female-related cancers. The two leading causes of cancer in the Western world today are tobacco and obesity. We’ve made enormous progress with tobacco-related malignancies—it’s really stunning. The next wave is obesity-related illness.”

Dr. Elizabeth A. Poynor, who is a gynecologic oncologist at Lenox Hill Hospital in New York City, added that this is just yet another risk that we can discuss with women who are obese, and yet another reason that obese women should consider losing weight.

Ovarian cancer is the fifth leading cancer killer of women in the U.S. and it is the leading killer among gynecologic malignancies. Only 37 percent of women that are diagnosed with this cancer survive beyond five years. Women who have already had children and have used an oral contraceptive appear to have a decreased risk of ovarian cancer. A person who has had a family history of ovarian cancer along with the use of HRT is known to contribute to the risk, and prior to this study there has been some evidence that being obese also increases the risk.

For this new study, the investigators from the U.S. National Cancer Institute followed approximately 95,000 U.S. women, who were between the ages of 50 to 71, for an average of seven years. Overall, women who are obese—categorized by having a body mass index (BMI) of 30 or above—had a 26 percent higher chance of getting ovarian cancer than women that have a normal weight, which is a figure that researchers said was not statistically significant.

However, the picture among subgroups of women is said to be somewhat different. Women who are obese that had never used hormone replacement therapy had an 80 percent higher risk of getting ovarian cancer, in comparison with their normal-weight counterparts. There appeared to be no relationship between the cancer and the body mass index among the women who had used the hormone replacement therapy for their menopause symptoms. Obese women who did not have a family history of ovarian cancer had a 36 percent higher risk of developing ovarian cancer, although there was no heightened risk in the obese women that did have a family history of the cancer.

According to the authors of the study, the findings indicate that obesity may increase the risk of ovarian cancer through hormonal effects. Specifically, excess fat increases the production of estrogen, which can spur the growth of ovarian cancer.

Dr. Michael Bookman, who is the vice president for ambulatory care and clinical researcher at Fox Chas Cancer Center for Philadelphia, said that the picture is likely much more complicated that the findings show. Overall, the obese women who participated in the study did not have a notably higher risk for getting the cancer. Bookman noted the only increased risk was seen in the subgroup of women. “When you do a subset analysis, there’s always a risk. They wave their hands and think maybe this is because estrogen is bad for you, but there are a lot of other things obesity does that creates endogenous estrogen, like other growth factors. It’s interesting that, in women who were exposed to menopausal hormones, there was some evidence that [hormones] actually protected them. It’s, at best, a modest effect and not nearly as strong as the data with endometrial cancer. I’m not a fan of obesity, but I think, in this particular analysis, it’s a pretty modest effect. It would be much more convicting if it were significant for the entire population.”