FSH Levels Predict Bone Loss in Premenopausal Women Treated for Breast Cancer More Than One Year After Treatment.

Context: Biomarkers to predict bone loss in premenopausal women after breast cancer treatment have not been examined.

Objective: To determine whether baseline FSH predicts subsequent bone loss.

Design: Secondary data analysis of the Exercise for Bone Health: Young Breast Cancer Survivors study, in which women were randomized to a 12-month exercise program or monthly health newsletter.

Setting: Community dwelling women.

Participants: A total of 206 women age less than or equal to 55 years at breast cancer diagnosis who had received adjuvant chemotherapy and were at least 1 year after diagnosis.

Intervention: Serum collected at baseline (an average of 302 ± 148 d after completing chemotherapy) was analyzed for FSH.

Main Outcome Measure: Change in bone mineral density.

Results: In linear regression models, baseline FSH levels predicted bone loss over the ensuing 12 months at the lumbar spine and femoral neck including after adjustment for age, ethnicity, treatment group (exercise vs control), baseline bone density, and high-sensitivity C-reactive protein (P < .001). In multiply adjusted models, the 12-month rate of change in bone density was +0.007% in the lowest tertile of FSH (FSH = 9 ± 7 IU/L, mean ± SD), -0.96% in the middle tertile (mean FSH = 41 ± 11 IU/L), and -2.2% in the highest tertile (mean FSH = 86 ± 19 IU/L), P for trend <.001.

Conclusions: Among premenopausal women with breast cancer treated with chemotherapy, baseline FSH levels are strongly associated with subsequent bone loss. Further studies are needed to establish the optimal timing of FSH measurement in relation to breast cancer treatment and to investigate potential strategies to prevent bone loss.