I have early menopause. What does this mean for my bones, and will I need treatment?

Whether your early menopause (also called premature menopause)^[1] is caused by surgery, is for unknown reasons, or is because of cancer treatments, your bones are at risk and you may need treatment.

When you are trying to cope with the treatments for cancer, it's hard to think about your bones and the possibility of developing osteoporosis so early in life. But the fact is that when you stop having your menstrual periods for whatever reason, your risk of bone loss increases. When you experience a natural menopause around the average age of 51, you can expect to lose bone most rapidly in the 4 to 8 years following menopause (starting 1 year after your last period). There are several reasons why you might experience menopause much earlier than that, and therefore need to cope with a larger stretch of your life without estrogen, an important hormone for bone growth.

A very small percentage of women (1%) experience natural menopause before the age of 40. It is not known why these women stop having their periods. Idiopathic ovarian insufficiency^[2] or premature ovarian failure^[3] is a condition that usually occurs in women under the age of 40 and causes menopause. Idiopathic ovarian insufficiency is usually caused by autoimmune and genetic disorders, Addison's disease (disorder of the adrenal glands, which manufacture steroid hormones), or hypothyroidism (an underactive thyroid gland).

Induced menopause is permanent menopause that occurs in women before their natural menopause. It occurs when the ovaries are removed along with the uterus and fallopian tubes (often called a total hysterectomy^[4]; the technical term is total hysterectomy with bilateral salpingo-oophorectomy)^[5]. Once the ovaries are removed, menopause is sudden and the accompanying symptoms of hot flashes, sleep disruptions, and mood changes can be quite severe. The ovaries no longer can secrete estrogen, and bone loss may start to occur almost immediately as well.

If only the uterus is removed, menopause occurs earlier than usual but not abruptly. An earlier menopause is believed to result from the decreased blood supply to the ovaries, which can occur after surgery to remove only the uterus. Many people have the misconception that if the uterus is removed, a woman goes into menopause. However, she only stops having menstrual periods; her ovaries continue to make estrogen. The estrogen will continue to have a protective effect on her bones until her ovaries stop producing estrogen, most likely earlier than the average age of 51. However, she will not be able to gauge exactly when menopause actually occurs because she will not have the usual cessation of her menses for 12 months, the hallmark of menopause.

Surgically induced menopause (removal of both ovaries) will cause you to lose bone fairly rapidly. It is important for you to prevent bone loss by getting the appropriate amounts of calcium (1200 to 1500 mg), vitamin D (400 to 800 IU), other necessary nutrients (see Table 6 in Question 53), and exercise. You should also be sure to make lifestyle changes that could improve your bone health, like avoiding heavy alcohol use and stopping smoking. In addition, you and your clinician may want to discuss medications for preventing bone loss. As long as your surgery did not result from cancer and you do not have any contraindications to taking them, you may take any of the medications that are approved for prevention of osteoporosis. If you are experiencing significant symptoms resulting from your induced menopause, a good option for you may be MHT (see Questions 64 and 66). Your clinician may also want to send you for BMD testing to get a baseline reading of your bones.

Induced menopause can also be a result of chemotherapy and radiation used to treat cancers. While surgically induced menopause always causes an abrupt stoppage of the production of estrogen by the ovary, chemotherapy and radiation to the pelvis stops ovarian secretion of estrogen, but sometimes this occurs over a longer period of time. This often means that women undergoing radiation and chemotherapy will have more time to adjust to the loss of estrogen. But it also means that they will begin to lose bone once the ovaries have stopped making hormones.

While women who have their ovaries removed for reasons unrelated to cancer could use MHT to treat their symptoms and to prevent osteoporosis, breast cancer survivors will have fewer options to treat their symptoms and to prevent bone loss. Few women who experience breast cancer can take estrogen because many cancers are linked to estrogen or are dependent on them for their growth (termed estrogen dependent or estrogen receptor positive cancer)^[6]. After treatment, some women with estrogen receptor positive cancer will be prescribed tamoxifen, an estrogen agonist/antagonist, to prevent a recurrence of breast cancer. Tamoxifen is known to increase bone mineral density in the spine by about 1% per year, but it causes bone loss in women who are healthy and premenopausal even though it increases BMD in healthy postmenopausal women. Nolvadex (tamoxifen) is not currently approved for the prevention or treatment of osteoporosis. Evista (raloxifene), another estrogen agonist/antagonist, is an option for breast cancer survivors if they are post-menopausal. Evista is FDA-approved for preventing invasive breast cancer in postmenopausal women with osteoporosis, or women who are at increased risk for invasive breast cancer. Evista is also approved for the prevention and treatment of postmenopausal osteoporosis (see Question 61).

Women whose breast cancers are not estrogen receptor positive generally are not treated with an estrogen agonist/antagonist. And most clinicians will not prescribe MHT to breast cancer patients even if the cancer is not estrogen dependent. Regardless of the type of breast cancer, any woman with chemotherapy-induced menopause will be at risk for losing bone. If you have a test that shows osteoporosis, your treatment options include the bisphosphonates, Evista, and calcitonin (see Questions 56-59, 61, and 63). Because many tumor cells secrete a substance related to parathyroid hormone, it is not clear if Forteo (teriparatide, a synthetic parathyroid hormone) would be an option for treatment in breast cancer survivors. Other treatment options are under study. For example, the bisphosphonate Zometa (zoledronate) is being evaluated for osteoporosis treatment in breast cancer survivors. So far, there is strong evidence that the bone density of the women taking Zometa has increased, but further study is needed to confirm the improvement and to document the long-term effects. Several options are also available to prevent osteoporosis in women who have had chemotherapy, such as the bisphosphonates and estrogen agonists/antagonists as well as lifestyle changes that include calcium supplementation, vitamin D, exercise, diet modifications, and smoking cessation.

Chemotherapy or pelvic radiation used to treat cancer can also induce menopause and the bone loss that follows the loss of estrogen. Although men don't experience menopause, they can have significant bone loss and fragility fractures when treated with GnRH agonists for prostate cancer. GnRH agonists such as Lupron are also used to treat endometriosis in women. Bone loss is one of the major side effects of Lupron.

Advanced breast cancer, advanced prostate cancer, and a cancer called multiple myeloma are all associated with bone metastases. The spread of cancer cells to the bone causes loss of strength of the bone, significant pain, and an increased risk of fracture. So those with cancer can have considerable bone loss and a significant increase in fractures, which result from the treatments for the cancer and the spread of the cancer itself.

• [1] Permanent (usually natural) menopause occurring in women younger than 40 years of age; also refers to women who have induced or surgical menopause.
• [2] The loss of ovarian function (and therefore fertility) in a woman under the age of 40, resulting in menopause. It is usually associated with other health conditions, and can sometimes be temporary. Also called premature ovarian failure.
• [3] Permanent menopause that is not natural; can be caused as a result of surgical removal of the ovaries, chemotherapy, or radiation to the pelvis.
• [4] Although technically only refers to removal of the uterus, "total" is sometimes used to refer to removal of the uterus, ovaries, and fallopian tubes.
• [5] Removal of fallopian tube and ovary; bilateral means both fallopian tubes and both ovaries are removed.
• [6] Type of cancer that is estrogen dependent or has receptors for estrogen.