For Women

The most frequent cause of hormone disturbance in women is when the ovary stops producing estrogen and progesterone. This may occur during surgery, with the removal of the ovaries for treatment of ovarian cancer or even breast cancer. Other treatments such as radiation therapy to the pelvis, chemotherapy, and medications such as tamoxifen, can reduce the amount of estrogen in a woman's body. Tamoxifen does not directly affect the ovary's ability to produce estrogen, but decreases the amount of estrogen available to the body.²⁰ Hot flashes are one of the main side effects of Tamoxifen and related drugs.²⁵ The combination of chemotherapy and tamoxifen seems to cause the greatest risk of having menopausal symptoms.^{3 13}

The closer you are to the age of menopause, the more likely chemotherapy will make the ovary stop functioning. Women age 40 and over have the greatest risk of permanent ovarian failure as a result of chemotherapy. Women under 40 may have their periods stop for a certain length of time but may find they will return to normal. The length of time varies by person.

Ovarian function may also be affected by the dose and type of chemotherapy received, with higher doses causing a greater risk of ovarian failure. Chemotherapy drugs called alkylating agents (such as cyclophosphamide) and anthracyclines (such as doxorubicin) are examples of drugs which tend to cause ovarian failure.

• Smoking, especially smoking more than 10 cigarettes per day^{31 21}
• Women who have not had any children¹⁷
• Lower body mass index³⁴

For Men

Treatment for prostate cancer in men frequently results in hormonal changes. Men who receive androgen ablation therapy for prostate cancer will have severely decreased levels of testosterone. Decreasing or blocking the action of hormones such as testosterone can be done through surgery (removing the testicles) or through medication.²⁶ Medications may be used to decrease or block male hormones. These include drugs that prevent the testicles from making testosterone (leuprolide, goserelin and buserelin), drugs that block male hormones from being active (flutamide and bicalutamide) and drugs that stop the adrenal gland from making testosterone (aminoglutethamide and ketoconazole). Some of the testosterone made within the body is changed into other hormones, including estrogen and 5alpha-dihydrotestosterone (DHT). Therefore, men with decreased levels of testosterone can experience side effects related to lowered levels of estrogen as well.²⁶