CHICAGO – A premenopausal breast cancer patient’s follicle-stimulating hormone level upon completion of chemotherapy predicts her risk of bone loss during the ensuing 12 months, Dr. Laila S. Tabatabai reported at the joint meeting of the International Congress of Endocrinology and the Endocrine Society.
“This may have significant implications for preserving bone health in premenopausal women with breast cancer. Appropriate use of FSH as a marker for premature ovarian failure and as a predictor of bone loss after breast cancer treatment may allow for the timely implementation of preventive measures to reduce fracture risk,” said Dr. Tabatabai of Johns Hopkins University, Baltimore.
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Higher FSH levels could signal the need for antiosteoporosis treatment.
She presented a secondary analysis from the Exercise for Bone Health: Young Breast Cancer Survivors Study, in which 206 women who were under age 55 and had completed adjuvant chemotherapy for breast cancer were randomized to a 12-month structured exercise program conducted through the YMCA or to a control group that received a monthly health newsletter.
Investigators measured baseline levels of FSH, bone turnover markers, calciotropic hormones, and high-sensitivity C-reactive protein. At 1 year follow-up, only baseline FSH level was significantly related to bone loss.
After adjustment for age, ethnicity, baseline bone mineral density, and assignment to the exercise or control arm, multivariate analysis showed that only women in the lowest tertile for baseline FSH – that is, a level of 21.1 IU/L or less – maintained their baseline bone mineral density at the lumbar spine. They averaged a 0.007% increase over 12 months. In contrast, women in the middle tertile, with a baseline FSH of 21.2-61.6 IU/L, had a mean 0.96% decrease in bone density, and those in the highest tertile, with an FSH of 61.7-124.6 IU/L, averaged a 2.2% bone loss.
“Of note, bone loss was seen with an FSH greater than 21 IU/L, a lower level than is typical of diagnostic criteria for premature ovarian failure,” Dr. Tabatabai observed.
Tamoxifen therapy, time since chemotherapy, and baseline estradiol levels were not related to bone loss or preservation. Baseline CTX (urinary C-terminal crosslinking telopeptide) was the only bone turnover marker associated with subsequent bone loss, but this relationship was marginal.
Also noteworthy was the finding that absence of menstruation did not predict bone loss, said Dr. Tabatabai. Less than 60% of women in the lowest FSH tertile reported menstruating both at baseline and at 12 months, yet they maintained bone mass.
Chemotherapy in premenopausal women often results in premature ovarian failure, bone loss, and amenorrhea. This comes about because the medications damage ovarian follicles and steroid-producing cells, with resultant reduced production of estradiol and inhibin B. This results in loss of feedback inhibition of pituitary gonadotropins along with increased FSH levels, Dr. Tabatabai explained.
She said that since hers is the first study to look at biomarkers to predict bone loss in premenopausal breast cancer patients after chemotherapy, the findings need confirmation. Further studies also should aim to pin down the optimal timing of FSH measurement in relation to breast cancer treatment.