QUESTION: I have polycystic ovary syndrome and my doctor said that I was at risk of developing endometrial cancer. Is this true and why?
ANSWER: It has been demonstrated in numerous studies that women who have not achieved a pregnancy have two to three times the risk of developing endometrial cancer compared to women who have been pregnant.
Many women who are unable to achieve a pregnancy are anovulatory. Anovulatory cycles result in chronic estrogen exposure to the endometrial lining (the lining of the uterus) and an increased risk of developing endometrial cancer. Polycystic ovary syndrome (PCOS) is one of the most common causes of anovulation.
It has also been noted that women who are 21 to 50 pounds overweight have a three fold increase in the risk of endometrial cancer. And women who weigh more than 50 pounds over their recommended weight have a 10 fold increase in risk.
It is felt that the peripheral conversion of adrenal androstenedione (an androgenic male hormone) to estrone results in chronic exposure of the endometrium to increased circulating estrogen, thus increasing the risk of endometrial cancer.
Polycystic ovary syndrome is often associated with weight problems. Estrogen producing ovarian tumors are also associated with an increased risk of endometrial cancer.
Women who do not undergo menopause until after 52 years of age are at a twofold increased risk of developing endometrial cancer. Anovulatory cycles in the perimenopausal years (the years preceding the natural menopause) again result in a prolonged exposure of the endometrium to progesterone-deficient menstrual cycles, thus increasing the risk of endometrial cancer. Diabetes mellitus also increases a woman's risk of developing endometrial cancer by greater than two fold. The menopausal use of estrogen replacement therapy without progestins increases the risk of endometrial cancer four to eight fold. Tamoxifen, the antiestrogen commonly used in the treatment of breast cancer, is also associated with a two to three fold increased risk for the development of endometrial cancer.
Routine Pap smears are inadequate for screening purposes. Transvaginal ultrasound, as a screen for endometrial cancer, is also of questionable value in asymptomatic (no irregular bleeding) women. Endometrial biopsy or D&C are utilized to detect endometrial hyperplasia or endometrial cancer and are performed in patients who are at significant risk or who have symptoms consistent with endometrial cancer (irregular bleeding).
Approximately 90 percent of women with endometrial cancer have vaginal bleeding or discharge as their only presenting complaint. Endometrial cancer most often occurs in women in the sixth and seventh decade of life. Those with abnormal perimenopausal or postmenopausal bleeding should always be investigated.
Your physician is practicing preventive medicine by informing you of your potential risks for endometrial cancer. Endometrial biopsies or a D&C may be indicated. Treatment of your particular condition (PCOS) may include inducing ovulation, periodic progestin administration or birth control pills. Continued followup will help to avoid the development of endometrial cancer. ## by C. Matthew Peterson, MD
Source:
http://health.ivillage.com/gyno/gynoovaries/0,,469s,00.html 
PCOS: Increased risk of cancer? 
