מתוך medicontext.co.il

By Jill Stein

PHOENIX (Reuters Health) – Adjuvant chemotherapy given to postmenopausal women with early breast cancer may decrease their bone mineral density (BMD), researchers announced here at the 23rd Annual Meeting of the American Society for Bone and Mineral Research.

Dr. Nancy C. Greep and colleagues at St. John's Health Center in Santa Monica, California reviewed the BMDs of all breast cancer patients who had been treated at their facility during a recent 8-year period for newly diagnosed breast cancer and had had a bone scan.

Patients who were premenopausal at the time of their initial diagnosis, had advanced disease, had other causes for bone disease, or whose only BMD was obtained prior to their breast cancer diagnosis, were not eligible for enrollment. Overall, 138 women were enrolled in the trial.

"The impact of adjuvant chemotherapy on the bone mineral density of women who are already postmenopausal at the time of breast cancer diagnosis is unknown," Dr. Greep explained. "However, since chemotherapeutic agents are known to have direct toxic effects on bone in [both] animal and in vitro models, we speculated that adjuvant chemotherapy might have an adverse impact on the bone mineral density of estrogen-deficient, postmenopausal women with early breast cancer."

Patients who received adjuvant chemotherapy were younger at the time of their cancer diagnosis than others. Otherwise, the profile of risk factors for low BMD was similar in the control and adjuvant chemotherapy groups.

Although all patients had early breast cancer by study design, women who received adjuvant chemotherapy had a higher stage of disease than controls. Results showed that in spite of being younger and fewer years beyond their menopause, patients who received adjuvant chemotherapy had BMDs less than or equal to those of controls.

Z-scores were about 0.5 lower in patients who received adjuvant chemotherapy compared with those who did not. The researchers also found that changes in BMD associated with adjuvant chemotherapy in postmenopausal women with early breast cancer may double their risk for fracture.

Dr. Greep told Reuters Health that a prospective study is needed to determine whether the lower BMD observed in the study patients who received adjuvant chemotherapy was a result of their therapy or a manifestation of their more advanced, although apparently still localized, breast cancer.

Future research, she added, should address the following questions: If adjuvant chemotherapy lowers the BMD of postmenopausal patients, what is the mechanism of this effect? Also, if adjuvant chemotherapy is toxic to the bone of postmenopausal women, can the adverse effects be prevented by any currently available pharmacologic agents?