Cancer

How does cancer increase the risk for bone loss?

Men and women with certain types of cancer such as breast cancer and prostate cancer are at a greater risk for developing bone loss due to certain medications and treatments required.  Various cancer treatments such as chemotherapy can increase the risk of osteoporosis for both men and women. Furthermore, women who develop breast cancer in their premenopausal years are often thrust into an early menopause by treatment, including chemotherapy, and may suffer rapid bone loss as a result.

Are there certain types of cancer more associated with osteoporosis?

It appears that men with prostate cancer and women with breast, ovarian or endometrial cancers are at the highest risks for bone loss due to hormonal changes.

How do the hormonal changes affect bone loss in men and women?

Bone loss in men generally begins later and advances more slowly than it does in women. Men tend to have larger and stronger bones than women and don't experience the abrupt hormonal changes that occur with menopause. But as they age, men do lose bone density, in part because of a natural decrease in testosterone and estrogen, which may be important for bone health in men also. By age 65 - 70, men and women lose bone mass at similar rates. This may be related to declining physical activity, use of medication, decreased vitamin D and impaired calcium absorption, all of which increase in the elderly and may be related to bone loss.

What influence does estrogen exposure have on a woman's risk for breast cancer and/or osteoporosis?

Estrogen levels in women may influence a woman's risk for breast cancer and osteoporosis. Bone mineral density may be a marker for cumulative estrogen exposure throughout a woman's life. The evidence suggests that the greater a woman's estrogen exposure, the lower the risk of osteoporosis but the greater the chance of developing breast cancer. Investigators found that older women with higher bone density (suggesting greater amounts of blood estrogen levels) were almost 3 times more likely to develop breast cancer than those with lower bone density. This does not mean, however, that women who have osteoporosis should believe that they are protected from developing breast cancer.

How do hormonal therapies that are used for cancer treatment affect the bones?

Tamoxifen has been shown to decrease bone mineral density in women who have not gone through menopause. However, in postmenopausal women tamoxifen seems to increase bone mineral density. In contrast, some of the newer hormonal treatments for breast cancer, such as lotrozole or femara seem to have a negative impact on bone mass in postmenopausal women.

Prostate cancer is the most common cancer in men, and hormone ablative therapy is a very important risk factor for developing osteoporosis. This type of hormone therapy, called androgen deprivation therapy (ADT), blocks the production of testosterone, and is commonly used in elderly men with prostate cancer who are not suitable for more aggressive treatment. In some studies, bone mineral density measurements were substantially lower in men with prostate cancer treated with ADT than in men not receiving the hormone ablative therapy.

Since osteoporosis is usually a silent disorder, an individual undergoing hormone therapy for the treatment of cancer should request a full osteoporosis evaluation from their doctor before starting hormone therapy. The evaluation should include a bone mineral density (BMD) test and possibly X-rays. If necessary, patients should be treated with osteoporosis medications and/or bone density should be repeated to determine if substantial bone loss might be occurring with treatment.

Does treatment for cancer increase the risk for bone loss and/or osteoporosis?

Breast cancer patients are at a greater risk for osteoporosis because many of the treatments aimed at fighting tumors reduce the amount of estrogen in the body. Women undergoing treatment for breast cancer may experience premature menopause, thus increasing their risk for bone loss, leading to osteoporosis. Some hormone medications used to eradicate tumors, such as aromatase inhibitors, also interfere with the body's natural estrogen production or estrogen action. Women experiencing ovarian and endometrial cancers also have a similar situation, placing them at a potentially higher risk for osteoporosis as well.

Does radiation treatment increase the risk for bone loss?

There is no convincing evidence that radiation therapy increases the risk of generalized bone loss. It may, however, affect risk of fracture in the bone underlying the treated area.

When is a bone mineral density test recommended for individuals with cancer or those having cancer treatments?

Individuals who will be receiving chemotherapy or hormonal therapy for the treatment of their cancer should obtain a bone mineral density (BMD) test prior to the start of therapy. By having this "baseline" exam, physicians can monitor bone mineral density over time and initiate osteoporosis medications when appropriate. Discuss sequential BMD testing with your doctor as a means to check for bone loss as a result of cancer therapy.

When I am being treated for cancer, how can I protect my bones?

There are some very simple steps to take to help protect your bones:

• If you smoke, STOP smoking
• Limit your alcohol consumption
• Exercise - Doing simple weight bearing activity like walking can make a difference
• Eat a healthy well-balanced diet, loaded with fruits, vegetables and whole grains
• Consume enough calcium each day through food and/or supplements
• Get enough vitamin D

Why is vitamin D so important?

Vitamin D plays a major role in the promotion of healthy bones by increasing calcium absorption.  There is some evidence that intake of adequate vitamin D along with enough calcium may reduce the risk for falls (by increasing muscle strength) and reduce the risk for fracture in postmenopausal women and seniors.

Vitamin D is manufactured in the skin following direct exposure to sunlight. The amount of vitamin D produced in the skin varies depending on the time of day, season, latitude, and skin pigmentation. As adults age, the ability to make vitamin D through the skin decreases resulting in a need to consume vitamin D in our diets or take supplements containing vitamin D. 

Experts have recommended an adequate intake (AI) of vitamin D between 400 and 600 international units (IU). Your doctor or medical professional may recommend more vitamin D than the Adequate Intakes (AI) recommended for the general population if you are at high risk for vitamin D deficiency or if you have been diagnosed with low serum vitamin D levels. It is important not to exceed 2000 IU/day of Vitamin D unless specifically recommended by your doctor or medical professional.

American Cancer Society: http://www.cancer.org/docroot/home/index.asp
National Cancer Institute: http://www.nci.nih.gov/
National Osteoporosis Foundation: www.nof.org
New York State Department of Health:
http://www.health.state.ny.us/nysdoh/cancer/center/cancerhome.htm
New York State Breast Cancer Hotline: http://www.adelphi.edu/nysbreastcancer/