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Anticancer drugs Femara, Arimidex, Aromasin aren't the only cause of bone loss in breast cancer survivors

Osteoporosis is a growing concern among breast tumor survivors, because certain cancer drugs can cause bone loss.

A new study has found that anticancer drugs aren't the only culprits. Among 64 breast cancer patients referred to a bone health clinic, 78 percent had at least one other cause of bone loss, including vitamin-D deficiency, excessive calcium excretion in urine and an overactive parathyroid gland.

Previous studies have found that chemotherapy can cause bone loss. Studies also have found that a class of breast cancer drugs called aromatase inhibitors can decrease bone mineral density and increase the risk of fractures in postmenopausal women. Aromatase inhibitors decrease the body's production of estrogen. While estrogen feeds cancer, it also protects against osteoporosis.
Aromatase inhibitors include Letrozole ( Femara ), Anastrazole ( Arimidex ) and Exemestane ( Aromasin ).

Researchers reviewed charts of 238 consecutive postmenopausal patients who had osteoporosis or osteopenia and were referred to the Loyola's Osteoporosis and Metabolic Bone Disease Center from 2000 to 2006.

Thirty eight percent of the breast cancer patients had vitamin D deficiency, compared with 51 percent of the non breast cancer patients. Another cause of osteoporosis, excessive calcium excretion in urine, was found in 16 percent of cancer patients and 8 percent of noncancer patients. And in 5 percent of patients, the parathyroid gland was overactive, producing a hormone that causes bone to lose calcium.

Vitamin D deficiency can be treated with prescription doses of vitamin D supplements. Excessive calcium excretion can be treated with a diuretic.
There are various treatments for parathyroid gland disorder, depending on its cause.

In certain breast cancer patients, bone loss from cancer drugs can be treated with osteoporosis drugs such as Alendronate ( Fosamax ).

Source: Loyola University Health System, 2008