Chemotherapy and Bone Loss

A presentation at the annual meeting of the American Society for Bone and Mineral Research has added to the growing body of evidence that chemotherapy in breast cancer patients may decrease their bone mineral density (BMD).

Chemotherapy causes the ovaries to suddenly stop producing estrogen. Among its other functions, estrogen protects the bones from deteriorating. All women gradually stop producing estrogen as part of the natural menopause process. However, with chemotherapy, the decline in estrogen production is much more rapid-causing a pronounced loss of bone density as a result.

Dr. Nancy Greep and colleagues from the St. John's Health Center in Santa Monica, California studied the records of 138 newly diagnosed postmenopausal breast cancer patients who had a BMD test performed prior to their diagnosis.

The researchers then compared changes in BMD for women who were treated with adjuvant chemotherapy with women who were given other treatment alternatives. They found that patients who received chemotherapy had BMDs less than or equal to those who did not receive adjuvant chemotherapy.

The researchers cautioned that the women who were given adjuvant chemotherapy tended to have more advanced disease. Further studies were therefore warranted to determine whether their lower BMD levels were a result of their chemotherapy or a manifestation of their more advanced, although apparently still localized, disease.

Premenopausal Women

An earlier study, published in the Journal of Clinical Oncology by Dr. Charles Shapiro of Ohio State University and colleagues reported that spinal bone density appears to decline at an alarming rate-up to 8 percent in premenopausal women after 12 months of treatment.

Shapiro's team assessed the spinal bone density of 49 women, median age 42, near the start of their chemotherapy regimen. Thirty-five of the women (71 percent) soon entered premature menopause as a result of their treatment. The extent of bone loss that these women experienced in such a short period of time surprised the researchers; in normal postmenopausal women, the rate of bone loss in the spine is approximately 1 - 2 percent a year.

"Chemotherapy-induced ovarian failure causes rapid and highly significant bone loss in the spine," they wrote. "This may have implications for long-term breast cancer survivors who may be at higher risk for osteopenia, and subsequently osteoporosis."

SOURCES:

23rd Annual Meeting of the American Society for Bone and Mineral Research, October 16, 2001, Phoenix, Arizona
Journal of Clinical Oncology, July 15, 2001; 19(14):3306-3311

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