Rosemary A. Hannon

Relationship of Early Changes in Bone Resorption to the Reduction in Fracture Risk With Risedronate

Changes in the level of biochemical markers of bone resorption with risedronate treatment for osteoporosis were examined as a surrogate for the decrease in fracture risk. Greater decreases in bone resorption markers were associated with greater decreases in vertebral (and nonvertebral) fractures.

Effect of Anastrozole on Bone Mineral Density: 5-Year Results From the Anastrozole, Tamoxifen, Alone or in Combination Trial 18233230

PURPOSE The Arimidex, Tamoxifen, Alone or in Combination (ATAC) trial (median follow-up, 68 months) has shown that adjuvant anastrozole has superior efficacy and better tolerability than tamoxifen. However, anastrozole reduces circulating estrogen, and low estradiol levels are associated with decreased bone mineral density (BMD) and increased fracture risk. It is therefore important to understand the effects of long-term aromatase inhibitor therapy on BMD. PATIENTS AND METHODS This prospective substudy of the ATAC trial assessed BMD changes in postmenopausal women with invasive primary breast cancer receiving anastrozole (1 mg/d) or tamoxifen (20 mg/d) as adjuvant therapy for 5 years. Lumbar spine and total hip BMD were assessed at baseline and after 1, 2, and 5 years. RESULTS One hundred ninety-seven women from the monotherapy arms of the ATAC trial were recruited onto the bone substudy, and 108 were included in the primary analysis. Among anastrozole-treated patients, there was a decrease in median BMD from baseline to 5 years in lumbar spine (-6.08%) and total hip (-7.24%) compared with the tamoxifen group (lumbar spine, +2.77%; total hip, +0.74%). No patients with normal BMD at baseline became osteoporotic at 5 years. CONCLUSION Anastrozole is associated with accelerated bone loss over the 5-year treatment period. However, although patients with pre-existing osteopenia are likely to require monitoring and bone-protection strategies, patients with normal BMD would not appear to require monitoring beyond the recommendation for healthy postmenopausal women. The effect of anastrozole on bone should be weighed against its superior efficacy and better tolerability profile versus tamoxifen in the main ATAC trial.

Effect of an Aromatase Inhibitor on BMD and Bone Turnover Markers: 2‐Year Results of the Anastrozole, Tamoxifen, Alone or in Combination (ATAC) Trial (18233230)

Aromatase inhibitors reduce estrogen levels in postmenopausal women with breast cancer. Residual estrogen is an important determinant of bone turnover. Adjuvant anastrozole was associated with significant BMD loss and increased bone remodeling, whereas tamoxifen reduced bone marker levels.

Response of Biochemical Markers of Bone Turnover to Hormone Replacement Therapy: Impact of Biological Variability

Biochemical markers of bone turnover may be useful to monitor patients taking hormone replacement therapy (HRT). The aim of this study was to assess the utility of markers in monitoring HRT by comparing the response of a large panel of markers to HRT with their within subject variability. We measured the response of markers to transdermal estradiol in 11 postmenopausal women over 24 weeks. We measured the within subject variability of markers in 11 untreated healthy postmenopausal women over the same period. The mean decrease in markers of bone formation after 24 weeks treatment ranged from 19% for procollagen type I C‐terminal propeptide (PICP) to 40% for procollagen type I N‐terminal propeptide (PINP). The mean decrease in markers of bone resorption ranged from 10% for tartrate‐resistant acid phosphatase (TRAP) to 67% for C‐terminal cross‐linked telopeptide. The least significant change (LSC at p < 0.05), calculated from the within subject variability in the untreated group, was used to define response. LSC for osteocalcin was 21%, bone alkaline phosphatase 28%, PICP 24%, PINP 21%, type I collagen telopeptide 28%, TRAP 17%, urinary calcium 90%, hydroxyproline 75%, total deoxypyridinoline 47%, free pyridinoline 36%, free deoxypyridinoline 26%, N‐terminal cross‐linked telopeptide 70%, and C‐terminal cross‐linked telopeptide 132%. The greatest number of responders after 24 weeks of treatment were found using PINP and osteocalcin (9 each), and free deoxypyridinoline (8 each) and total deoxypyridinoline (7 each). Lumbar spine bone mineral density defined four patients as responders. The ability to detect a response differs between markers and is not dependent on the magnitude of response to therapy.

Effect of feeding on bone turnover markers and its impact on biological variability of measurements

Bone turnover markers are subject to day-to-day and within-day variability, which may influence clinical interpretation. We examined the effect of fasting vs. feeding on the concentration and between-day variability of several markers. Twenty healthy premenopausal women were studied on 10 consecutive weekdays. Subjects were studied either in the fasting (no breakfast) or fed (breakfast at 08:00 h) state on alternate days, and were randomized to begin either fasting or fed. Two hour urine collections were obtained each day between 08:00 h and 10:00 h, and blood samples were collected daily at 09:00 h. The N-telopeptide cross-link of type I collagen in urine (uNTX) and serum (sNTX), the C-telopeptide in urine (uCTX) and serum (sbetaCTX), and immunoreactive free deoxypyridinoline (uifDPD) in urine were measured as resorption markers. Procollagen type I N-terminal propeptide (PINP), osteocalcin (OC), and bone alkaline phosphatase (bone ALP) were measured as formation markers. All bone formation and resorption markers were significantly lower in the fed state with the exception of bone ALP. The magnitude of the decrease ranged from 3.8 +/- 0.9% for PINP (p < 0.0001) to 17.8 +/- 2.6% (p < 0.0001) for sbetaCTX. Measurement variability was partitioned into analytical variability based on replicate assays (CV(a)) and within-subject variability (CV(i)). The CV(i) was greater (p < 0.05) for some markers in the fasting state (uifDPD, uNTX, and sNTX) but greater in the fed state for other markers (OC and sbetaCTX). In conclusion, the clinical impact of feeding vs. fasting is small with the exception of sbetaCTX; however, in clinical practice, collection of samples in the fasting state may be necessary to minimize the unpredictable effects of feeding. The mechanism of the acute effect of feeding on bone turnover remains uncertain.

Biochemical markers of bone turnover in girls during puberty

OBJECTIVES Bone turnover and the rate of bone growth increase dramatically during puberty. A number of new assays for the estimation of bone resorption and formation rates have been developed over recent years, and puberty acts as a convenient model for evaluation of these measurements. The aim of this study was to explore the interrelationships between pubertal development, biochemical markers of bone turnover, Insulin‐like growth factor I and oestradiol in healthy pubertal girls.

Prevention of Aromatase Inhibitor-Induced Bone Loss Using Risedronate: The SABRE Trial

PURPOSE To investigate the management of bone health in women with early breast cancer (EBC) who were scheduled to receive anastrozole. PATIENTS AND METHODS Postmenopausal women with hormone receptor-positive EBC were assigned to one of three strata by risk of fragility fracture. Patients with the highest risk (H) received anastrozole 1 mg/d plus risedronate 35 mg/wk orally. Patients with moderate-risk (M) were randomly assigned in a double-blind manner to anastrozole and risedronate (A + R) or to anastrozole and placebo (A + P). Patients with lower-risk (L) received anastrozole (A) alone. Calcium and vitamin D were recommended for all patients. Lumbar spine and total hip bone mineral density (BMD) were assessed at baseline, 12 months, and 24 months. Results At 24 months, in the M group, treatment with A + R resulted in a significant increase in lumbar spine and total hip BMD compared with A + P treatment (2.2% v -1.8%; treatment ratio, 1.04; P < .0001; and 1.8% v -1.1%; treatment ratio, 1.03; P < .0001, respectively). In the H stratum, lumbar spine and total hip BMD increased significantly (3.0%; P = .0006; and 2.0%; P = .0104, respectively). Patients in the L stratum showed a significant decrease in lumbar spine BMD (-2.1%; P = .0109) and a numerical decrease in total hip BMD (-0.4%; P = .5988). Safety profiles for anastrozole and risedronate were similar to those already established. CONCLUSION In postmenopausal women at risk of fragility fracture who were receiving adjuvant anastrozole for EBC, the addition of risedronate at doses established for preventing and treating osteoporosis resulted in favorable effects in BMD during 24 months.

Prevention of Anastrozole-Induced Bone Loss with Monthly Oral Ibandronate during Adjuvant Aromatase Inhibitor Therapy for Breast Cancer

Purpose: The aromatase inhibitor anastrozole is a highly effective well-tolerated treatment for postmenopausal endocrine-responsive breast cancer. However, its use is associated with accelerated bone loss and an increase in fracture risk. The ARIBON trial is a double-blind, randomized, placebo-controlled study designed to evaluate the impact of bisphosphonate treatment on bone mineral density (BMD) in women taking anastrozole. Experimental Design: BMD was assessed in 131 postmenopausal, surgically treated women with early breast cancer at two U.K. centers. Of these, 50 patients had osteopenia (T score −1.0 to −2.5) at either the hip or lumbar spine. All patients were treated with anastrozole 1 mg once a day and calcium and vitamin D supplementation. In addition, osteopenic patients were randomized to receive either treatment with ibandronate 150 mg orally every month or placebo. Results: After 2 years, osteopenic patients treated with ibandronate gained +2.98% (range −8.9, +19.9) and +0.60% (range −9.0, +6.9) at the lumbar spine and hip, respectively. Patients treated with placebo, however, lost −3.22% (range −16.0, +4.3) at the lumbar spine and −3.90% (range −12.3, +7.2) at the hip. The differences between the two treatment arms were statistically significant at both sites (P < 0.01). At 12 months, urinary n-telopeptide, serum c-telopeptide, and serum bone–specific alkaline phosphatase levels declined in patients receiving ibandronate (30.9%, 26.3%, and 22.8%, respectively) and increased in those taking placebo (40.3%, 34.9%, and 37.0%, respectively). Conclusions: Monthly oral ibandronate improves bone density and normalizes bone turnover in patients treated with anastrozole.

Biochemical markers as predictors of rates of bone loss after menopause

Biochemical markers of bone turnover may correlate with rates of bone loss in a group of postmenopausal women, but it is uncertain how useful they are in predicting rates of bone loss in the individual. The aim of this study was to determine the value of measurements of biochemical markers for the prediction of rates of bone loss in the individual. We studied 60 postmenopausal women (ages, 49–62 years), 43 of whom had gone through a natural menopause 1–20 years previously and 17 of whom had undergone hysterectomy 3–22 years ago. Lumbar spine bone mineral density (BMD) was measured using dual‐energy X‐ray absorptiometry (DXA) over 2–4 years. Bone formation markers (bone‐specific alkaline phosphatase [ibAP] and amino terminal of type I collagen [PINP] and osteocalcin [OC]) were measured in serum. Bone resorption markers (N‐telopeptide of type 1 collagen [NTx] and immunoreactive free deoxypyridinoline [iFDpd]) were measured in urine and corrected for creatinine (Cr). Rates of bone loss were calculated as percent change per year. We found significant negative correlations (Spearman rank) between all measured biochemical markers and rate of change in bone density with r values ranging from −0.35 to −0.52. When markers and rates of bone loss were divided into tertiles, prediction of bone loss in an individual was poor (κ < 0.2). There was an exponential relationship between rate of bone loss and years since menopause (YSM) in the 43 women having a natural menopause (r2 = 0.44; p = 0.008) indicating higher rates of loss in the early postmenopausal period. Levels of NTx, iFDpd, and PINP also showed a significant negative correlation with YSM. We conclude that there is a strong relationship between rates of spinal bone loss and levels of bone turnover markers. Although this is a small study, the results also suggest that using DXA measurements of the lumbar spine as the “gold standard,” it is not possible to use biochemical markers to predict rate of bone loss in the individual.

Biomarkers of bone health and osteoporosis risk

The assay features of biochemical markers of bone turnover have markedly improved in the past few years. The most sensitive and specific markers of bone formation include serum bone alkaline phosphatase, total osteocalcin (including the intact molecule and the large N-mid fragment) and the procollagen type I N-terminal propeptide assay. Among the various markers of bone resorption, measurements of the urinary excretion of N- and C-terminal cross-linked telopeptides) and of serum C-terminal cross-linked telopeptides are the most sensitive and specific. Markers of bone turnover can be used to predict the rate of bone loss in post-menopausal women and can also be used to assess the risk of fractures. In osteoporosis-treatment studies (with alendronate, risedronate, raloxifene) markers of bone turnover appear even more strongly associated with fracture risk reduction than bone mineral density (BMD). These observations support the use of markers of bone turnover as surrogates for fracture risk reduction, perhaps even more so than BMD. Bone markers can also be used to monitor the efficacy of antiresorptive therapy such as hormone-replacement therapy, raloxifene and bisphosphonates in individual patients. Furthermore, they have also proved to be helpful in monitoring the response to nutritional interventions and have the advantage over BMD in that they provide information about mechanism of effect and changes are often observed much more rapidly.