Obesity and Ovarian Cancer

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Obesity has been found to be a risk factor for a number of different cancers, including cancers of the breast, colon, esophagus, pancreas, ovaries, and others.

Obesity Increases Risk of Certain Forms of Cancer

According to the National Cancer Institute (NCI), obesity is associated with increased risk for certain cancers, including cancers of the breast in postmenopausal women, and cancers of the esophagus, endometrium (which is the lining of the uterus), kidney, ovaries, pancreas, thyroid, colon and rectum, gallbladder, and possibly others.

One study that used data from the NCI’s SEER (Surveillance, Epidemiology, and End Results) database estimated that approximately 50,500 new cases of cancer in women and 34,000 new cases in men were due to obesity for the year 2007 in the United States. For some cancer types, the percentage of cases due to obesity was as high as 40 percent, including for endometrial cancer and cancer of the esophagus.

Obesity as a Risk Factor for Ovarian Cancer

So, if you have obesity, are you at risk for ovarian cancer? Well, there are many risk factors that have been identified for ovarian cancer, with genetics and family history playing a primary role. However, it has been discovered that obesity is also a risk factor.

Fortunately, ovarian cancer is relatively rare, but when it does strike, it can be deadly. According to the American Cancer Society, ovarian cancer accounts for approximately 3% of cancers among women, but it causes more deaths than any other cancer of the female reproductive system.

One study showed an association between high body mass index (BMI) and the development of ovarian cancer. Of note is that obesity appeared to increase the risk of rarer forms of ovarian cancer, but did not appear to increase the risk of high-grade invasive cancers (known as serous cancers) in this analysis.

Another study of 94,525 U.S. women who were followed for seven years found an association between obesity and increased risk for ovarian cancer; these investigators felt that their results suggested a hormonal mechanism for this link. Obesity can increase levels of female hormones like estrogen, and this may be playing a role in increased risk of ovarian and breast cancer.

How Is Obesity Associated with Cancer?

It is known that adipose (fat) tissue produces excess amounts of estrogen. High levels of estrogen have been linked to an increased risk of endometrial and breast cancer.

In addition, obesity often causes the body to have increased levels of insulin and a related factor known as insulin-like growth factor-1 (IGF-1), which, in addition to its normal physiologic functions of stimulating growth during childhood and helping to repair and build muscle tissue in adulthood, may promote the development and growth of certain tumors, particularly when it is present at higher-than-normal levels, as it is in obesity.

Obesity is also associated with greater systemic inflammation on a chronic basis, and this has been associated with an increased risk of cancer overall.

Furthermore, adipose cells produce other hormones, known as adipokines, that can stimulate cell growth. One of these growth-stimulating adipokines is leptin, which is also known as a satiety factor, and is present at higher levels in obese individuals. Cell growth that is out of control is, essentially, the definition of cancer.

How Can You Reduce Your Risk?

Losing even just 5 percent to 10 percent of excess weight can make a big impact on your overall health, including your risk for cancer.

Other lifestyle changes that you can make to reduce your risk of cancer include getting enough daily exercise, staying physically active throughout the day, and avoiding cancer-causing foods like processed meats.

Also, if you have a family history of ovarian or breast cancer, make sure your doctor knows about this, since genetics and family history play a big role in these particular cancers, and genetic screening tests are available and may be helpful.

Sources

American Cancer Society. Ovarian Cancer. 2015.

Ballard-Barbash R, Berrigan D, Potischmann N, Dowling E. Obesity and cancer epidemiology. In: Berger NA, editor. Cancer and Energy Balance, Epidemiology and Overview. New York: Springer-Vertag New York, LLC, 2010.

Leitzmann MF, Koebnick C, Danforth KN, et al. Body mass index and risk of ovarian cancer. Cancer 2009;115:812-822.

Olsen CM, Nagle CM, Whiteman DC, et al. Obesity and risk of ovarian cancer subtypes: evidence from the Ovarian Cancer Association Consortium. Endocr Relat Cancer 2013;20:251-262.

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