Test Your Knowledge

Although the exact cause of endometrial cancer is unknown, there are certain risk factors that may increase an individual’s likelihood of developing this disease. The ovaries are sex glands that produce eggs and usually produce two main kinds of female hormones called estrogen and progesterone. The balance between these hormones changes every month during a woman’s menstrual cycle to produce a woman’s monthly periods and maintain the health of the endometrium. Any shift toward high cumulative exposure to estrogen increases a woman’s risk of endometrial cancer. Many of the recognized risk factors for endometrial cancer are related to exposure to estrogen. Risk factors include:

• Obesity. According to the American Cancer Society (ACS), women who are seriously overweight have more than three times the risk of developing endometrial cancer than women of average weight. A higher level of fat tissue can raise estrogen levels in women, thereby increasin the risk of endometrial cancer.
  
  
• Age. According to the ACS, 95 percent of endometrial cancers affect women age 40 and older. The greatest number of cases occur between the ages of 55 and 64. As a woman ages, her risk of endometrial cancer increases.
  
  
• Early menarche (onset of menstruation). Women who start their monthly periods before the age of 12 have an increased risk of developing endometrial cancer due to extended estrogen exposure of the endometrium.
  
  
• Late menopause. Experiencing menopause after age 50 also increases risk of endometrial cancer because of the cumulative exposure of the endometrium to estrogen.
  
  
• Length of menstrual span (total). This factor may be more important than an individual’s age at menarche or menopause. For instance, early menarche is not as big a risk factor for women with early menopause because the endometrium has not been exposed to estrogen for a prolonged period.
  
  
• History of infertility (the inability to conceive a child). The balance between estrogen and progesterone shifts toward more progesterone during pregnancy. Therefore, having multiple pregnancies reduces the risk of endometrial cancer, whereas women who have never been pregnant have a greater risk of developing the disease.
  
  
• Hormone replacement therapy (HRT). HRT uses medications (progesterone and estrogen together or estrogen alone) to replace the natural hormones that are no longer produced, as with menopause. Although estrogen alone has been prescribed to treat menopause and osteoporosis, physicians have found that using estrogen on its own significantly increases the risk of endometrial cancer. Studies have shown that using progesterone and estrogen HRT (as opposed to estrogen only) may help avoid the additional risk of endometrial cancer. Women using or considering any HRT should discuss the effects with their physician and schedule regular follow-up examinations for cancer.
  
  
• Breast or ovarian cancerovarian cancer. Patients who have had breast or ovarian cancer may have a greater risk of developing cancer of the endometrium.  Some of the reproductive, hormonal and dietary risk factors for these cancers can also increase the risk of endometrial cancer.
  
  
• Other ovarian diseases. Certain ovarian tumors, including benign growths, produce estrogen, such as granulose-theca cell tumors. Also, women with polycystic ovaries have higher than normal levels of estrogen and lower levels of the hormone progesterone. The estrogen to progesterone ratio for both of these conditions can increase a woman’s likelihood of developing endometrial cancer.
  
  
• Diet high in animal fat. Fatty foods are high in calories, and therefore can lead to obesity, a well-known risk factor for various diseases, including endometrial cancer. Some scientists believe that fatty foods may have a direct effect on the metabolism of estrogen, which also increases the risk of developing endometrial cancer.
  
  
• Diabetes. For unknown reasons, women with diabetes are more likely to develop endometrial cancer than individuals without diabetes. Some physicians attribute this increased cancer risk to excess body weight because many people with type 2 diabetes are overweight. However, this theory does not explain why women with type 1 diabetes, which is not characterized by excess body weight, also have higher endometrial cancer rates.
  
  
• Family history. Some people have an inherited tendency to develop a specific form of colon cancer, hereditary nonpolyposis colon cancer (HNPCC). Studies have shown that at least half of women with HNPCC will also develop endometrial cancer.
  
  
• Race. White women have a greater risk of developing endometrial cancer. However, black women have a greater risk of dying from the disease.
  
  
• Prior pelvic radiation therapy. Patients who have had radiation therapy in the past may have an increased risk of developing endometrial cancer because radiation can damage DNA, promoting the growth of some secondary cancers.
  
  
• Tamoxifen. This antiestrogen drug is used to treat certain patients with breast cancer. It is also prescribed to lower the risk of breast cancer in women with increased risk of developing breast cancer. Even though tamoxifen is an estrogen-blocking drug, it functions like estrogen in the uterus. Therefore, patients taking tamoxifen have an increased risk of developing endometrial cancer. Those women who are prescribed tamoxifen should regularly visit their gynecologist (a physician who specializes in women’s health care and reproductive issues). In addition, these women should immediately report any signs and symptoms of endometrial cancer, which affects about one out of every 500 users of tamoxifen.