September is National Ovarian Cancer month!
Ovarian cancer is a type of cancer that begins in the ovaries, which are responsible for the production of eggs and the hormones estrogen and progesterone1. According to the American Cancer Society, ovarian cancer accounts for about 3% of cancers among women. It is the most fatal of all the cancers affecting the female reproductive system. It currently ranks fifth in all cancer deaths for women, killing about 14,000 individuals per year. One of the reasons ovarian cancer deaths rank so high may be because the cancer has few or non-specific symptoms, such as bloating, abdominal pain, early satiety, and fatigue. Screening is also difficult; tumors are difficult to feel during exams, and a pap test does not identify ovarian tumors.
One of the biggest risk factors for developing ovarian cancer is age1. Over half of all cases occur in women who are 65 and older, and diagnosis is rare before age 40. Another risk factor includes the number of lifetime menstrual cycles. That is, women who began menstruating before age twelve and experienced a late natural menopause are at an increased risk. Additional risk factors include the following:
- Family history of ovarian, breast, or colorectal cancer
- Having a mutation in the BRCA tumor suppressor genes
- Personal history of breast cancer
- Being overweight or obese
- Use of hormone replacement therapy
Conversely, use of oral contraceptives seem to decrease risk. Having children and breastfeeding appears to be protective against this cancer as well. For more information on risk factors, visit the American Cancer Society at www.cancer.org
Remember, ovarian cancer incidence is rare, and having a risk factor does not mean you will get the cancer. However, recognize that lifestyle can impact your risk for not only ovarian cancer but all types of cancers. Researchers have found that cancer risk, including ovarian cancer, increases with BMI2. The American Institute for Cancer Research estimated that 5% of U.S. ovarian cancer cases could be avoided by maintaining a healthy body weight3.
Obesity and Cancer Risk
Obese individuals experience a constant low-level of inflammation in the body4. Adipose tissue, or body fat, encourages higher circulating levels of insulin and leptin. These hormones have an important role in maintaining blood sugar levels and hunger cues5. However, when they are constantly elevated, as they are in obese individuals, they may promote cancer cell growth4. In addition, adipose tissue is the main site of estrogen production in post-menopausal women. Excess estrogen is associated with hormone-sensitive cancers, including breast and ovarian.
Nutrition Strategies to Reduce Cancer Risk
There are currently no known foods or nutrients that will cure ovarian cancer. However, there are dietary patterns associated with reduced cancer risk in general. For example, diets rich in fruits, vegetables, whole-grains, and lean-proteins such as the DASH eating plan and Mediterranean diet, provide ample amounts of fiber, antioxidants and heart-healthy fats. In addition, a healthy diet will help you maintain a healthy body weight, thereby decreasing your risk for cancer and other chronic diseases. See below for some common cancer nutrition myths and facts!
Dairy Causes Ovarian Cancer
In some studies, dairy consumption has been associated with ovarian cancer incidence and survival6,7. Researchers found that higher pre-diagnosis intakes of dairy products, along with red and processed meats, were associated with decreased longevity after ovarian cancer diagnosis7. This means that people who ate more red/processed meats and dairy foods before the cancer diagnosis had a shorter survival time after diagnosis. However, this does not mean that milk, cheese, yogurt, etc. caused the cancer, and these results have been inconsistent. This topic remains controversial. Bottom line? You can’t go wrong by incorporating more plant-based meals. Aim for five servings of fruits and vegetables daily. Calcium-set tofu is a rich source of both protein and calcium. Other plant sources of calcium include collard and mustard greens, broccoli, and okra. Since post-menopausal women are also at an increased risk for osteoporosis, consult with your registered dietitian (RD/N) before completely removing dairy from your diet.
Sugar Feeds Cancer
Sugar, in the form of glucose, is a fuel source for many cells in the body, including cancer cells! However, it is important to differentiate between added sugars and sugars that are naturally found in foods. Keep in mind that nearly all carbohydrates get broken down into glucose during digestion. In order to eliminate all sources of glucose one would have to avoid many healthy sources of carbohydrate including fruits, vegetables, and whole grains. That hardly sounds like a balanced diet! Added sugars on the other hand, such as those found in soft drinks, sugary cereals, doughnuts/pastries, and candies provide excess calories overall with minimal nutrients. These foods also contribute to blood sugar and insulin spikes, resulting in poor appetite control, low energy, and increased risk for chronic disease, including cancer.
Soy Foods Cause Cancer
There was concern for some time over the effect of soy on hormone sensitive cancers, such as breast and ovarian. Soy foods, including soy beans (edamame), tofu, miso, tempeh, and soy milk, are a rich source of phytoestrogens. Phytoestrogens are compounds in plants that have a structure similar to human estrogen (but do not contain estrogen)8. Since estrogen tends to increase risk for hormone sensitive cancers, the theory was that these phytoestrogens might increase risk as well. However, this is not the case. Most healthcare professionals agree that soy foods are safe to consume. Those who enjoy whole soy foods actually tend to have a lower risk of breast cancer9! Avoid high-dose soy supplements, but feel free to add whole soybeans, tofu, or tempeh to your salad or stir-fry.
Research in nutrition is constantly growing, changing and, hopefully, improving! It can be frustrating to try to navigate the wealth of information available. Find some comfort in knowing that a few core principles have not changed: eat more fruits and vegetables, choose whole grains over refined, and stick with lean protein options!
- American Cancer Society. What is Ovarian Cancer? http://www.cancer.org/cancer/ovariancancer/detailedguide/ovarian-cancer-what-is-ovarian-cancer. Accessed 8/19/16.
- Lauby-Secretan, et al. Body Fatness and Cancer – Viewpoint of the IARC Working Group. New England Journal of Medicine. 2016; 375(8): 794.
- American Institute for Cancer Research. The Prevention of Ovarian Cancer. 2014; http://www.aicr.org/continuous-update-project/ovarian-cancer.html . Accessed 8/19/16.
- American Institute for Cancer Research. Continuous Update Project: Ovarian Cancer 2014 Report. 2014; http://www.aicr.org/continuous-update-project/ovarian-cancer.html. Accessed 8/19/16.
- McCulloch,Marsha. Appetite Hormones. Today’s Dietitian.2015; 17(7): 26. http://www.todaysdietitian.com/newarchives/070115p26.shtml. Accessed 8/19/16.
- Larsson, Orsini, & Wolk. Milk, milk products and lactose intake and ovarian cancer risk: A meta-analysis of epidemiological studies. International Journal of Cancer. 2006; 118(2): 431-441.
- Dolecek, et al. Prediagnosis Food Patterns Are Associated with Length of Survival from Epithelial Ovarian Cancer. Journal of the Academy of Nutrition and Dietetics.2010; 110(3):369-382. Accessed 8/25/16.
- Patisaul & Jefferson. The pros and cons of phytoestrogens. Frontiers in Neuroendocrinology. 2010;31(4): 400-419.
- Leser, Ledesma, Bergerson, & Trujillo. Oncology Nutrition for Clinical Practice. The Academy of Nutrition and Dietetics Oncology Nutrition Dietetics Practice Group. 2013.