Cancer Drugs Aren't the Only Culprits
MAYWOOD, Il. -- Osteoporosis is a growing concern among breast cancer survivors and their doctors, because certain cancer drugs can cause bone loss.
Many breast cancer patients also experience secondary causes of bone loss, such as vitamin D deficiency.
But a Loyola University Health System study has found that bone loss can be halted with a comprehensive regimen that includes both osteoporosis drugs and treatments that target secondary causes of bone loss.
The study by Dr. Pauline Camacho and colleagues was presented at the annual meeting of the American Society for Bone and Mineral Research.
"Doctors evaluating breast cancer patients for possible bone loss should look further than cancer drugs," Camacho said.
Primary causes of osteoporosis are menopause and aging. Secondary causes are diseases or conditions that exacerbate bone loss.
A class of breast cancer drugs called aromatase inhibitors can decrease bone mineral density and increase the risk of fractures in postmenopausal women. The drugs decrease the body's production of estrogen. While estrogen feeds cancer, the hormone also protects against osteoporosis. In certain breast cancer patients, bone loss from cancer drugs can be treated with osteoporosis drugs called bisphosphonates, such as alendronate sodium (FosamaxÂ®) and ibandronate sodium (BonivaÂ®).
Camacho and colleagues reviewed charts of 81 consecutive breast cancer patients who were referred to Loyola's Osteoporosis and Metabolic Bone Disease Center for treatment or prevention of osteoporosis. Fifty-one patients had secondary causes of bone loss, including Vitamin D deficiency (65 percent), excessive calcium excretion in urine (16 percent) and an overactive parathyroid gland (13 percent). Thirty patients did not have secondary causes of bone loss.
Each group received similar treatment with osteoporosis drugs. Women with secondary bone loss also received additional treatments. For example, vitamin D deficiency was treated with prescription doses of vitamin D supplements. Excessive calcium excretion was treated with a "water pill" that's also used to treat high blood pressure. There were various treatments for parathyroid gland disorder, depending on the cause.
After one year, the breast cancer patients with secondary causes of bone loss had stable bone mineral density in their spines and necks. Bone mineral density improved in the group of breast cancer patients who did not have secondary causes of bone loss. (Bone mineral density -- the amount of calcium and other minerals packed into a segment of bone -- predicts osteoporosis.)
Camacho said the study demonstrates that bone loss "can be prevented in women undergoing hormonal therapy if secondary causes of bone loss are corrected and bisphosphonate osteoporosis drugs are appropriately used." Camacho is an associate professor of medicine at Loyola University Chicago Stritch School of Medicine and director of Loyola's Osteoporosis and Metabolic Bone Disease Center.
Camacho's co-authors are Dr. Kathy Albain, Dr. Patricia Robinson and Stritch medical student Naseem Helo. Albain is a professor and Robinson is an assistant professor at Stritch. Both are in the department of medicine, division of hematology/oncology.