Breast Cancer and Osteoporosis

Osteoporosis causes the bones to become weak and more likely to break. This is due to the rapid loss of bone mass or density. While anyone can develop osteoporosis it is most prevalent in older women. It is estimated that as many as half of all women over the age of 50 will break a bone due to osteoporosis.

Osteoporosis is a silent disease that can often be prevented; nevertheless it can progress for many years without symptoms until a fracture occurs. While a cause for osteoporosis is not known, several risk factors have been identified. Breast cancer and osteoporosis seemed to be linked for a few reasons.

Risk Factors

One of the reasons that breast cancer and osteoporosis may be linked is that they share some of the same risk factors. The risk of getting breast cancer increases with age, as it does with osteoporosis. The risk of getting breast cancer is highest for women who are over 60. Women in this demographic are already at risk of developing osteoporosis since the risk of osteoporosis increases with age and is more prevalent in women.

Sometimes, low bone mass or osteoporosis is already present before breast cancer is diagnosed. Breast cancer treatment may improve, worsen or have no impact on the pre-existing condition.

Women who have had breast cancer may be at higher risk for osteoporosis than other women for a number of reasons. Early menopause is one such cause. Early menopause may result from the ovaries being removed or irradiated. These procedures are done to slow breast cancer growth since estrogen can cause some breast tumors to grow. This sudden lowering of estrogen levels can result in rapid bone loss.

Osteoclasts

A breast tumor itself can increase the bone dissolving activity of the osteoclasts and cause an increase in the risk of osteoporosis. Osteoclasts are special cells that absorb bone, allowing for the deposition of new bone and maintenance of bone strength.

Chemotherapy drugs such as doxorubicin and methotrexate may not only cause early menopause but also can prevent bone formation and cause a loss of bone density. With some types of breast cancer the hormones estrogen and progesterone can speed up tumor growth. Hormonal therapies are often used to prevent this from happening. Various types of hormonal therapies can also speed up bone loss and cause osteoporosis.

Certain drugs also forge a link between breast cancer and osteoporosis. A recent study, known as STAR or the study of Tamoxifen and Raloxifene initially shows that the same drugs used in treatment and prevention of osteoporosis may also be used for breast cancer and vice versa.

Tamoxifen has been shown to decrease bone density in pre menopausal women, however seems to increase bone density in postmenopausal women. Raloxifene, which is used to treat osteoporosis, was recently found to be effective in preventing breast cancer in women at high risk. As with any treatment plan come both benefits and risks. Since it appears that women who have had breast cancer treatments are at higher risk for developing osteoporosis, extra caution and preventative methods should be considered.