The effect of adjuvant aromatase inhibitors on BMD in women with breast cancer

Study Type: Therapy
OE Level of Evidence: 2
Journal Level of Evidence: N/A
Synopsis
497 postmenopausal women with hormone-receptor-positive breast cancer were randomized to receive adjuvant exemestane 25 mg or anastrozole 1 mg daily for 5 years. Two subgroups were identified: those with baseline T-scores of -2.0 or greater at the spine and hip (subgroup 1), and those with baseline T-scores less than -2.0 at the spine and hip and taking bisphosphonates (subgroup 2). Results at 2 Please login to view the rest of this report. Please login to view the rest of this report.
Funding: Industry funded
Sponsor: Canadian Cancer Society Research Institute, Pfizer, Canadian Institutes of Health Research
Conflicts: Other
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Why was this study needed now?
Aromatase inhibitors play an important role in the treatment of postmenopausal women with hormone-receptor-positive breast cancer. As aromatase inhibitors work by decreasing circulating estrogen, a number of serious adverse effects (such as decreased bone mineral density and a subsequent increase in fracture risk) may be more probable in this population. A previous trial compared the adjuvant effects of the steroidal (exemestane) and non-steroidal (anastrozole) classes of aromatase inhibitors, indicating no significant difference in event-free survival, and fewer newly-diagnosed cases of osteoporosis or osteopenia with exemestane. The current study was conducted alongside this randomized controlled trial to investigate bone health in these patients.
What was the principal research question?
How do changes in bone mineral density compare between adjuvant exemestane versus adjuvant anastrozole in the treatment of postmenopausal women with hormone-receptor-positive breast cancer, when assessed over 2 years? Additionally, what effect did bisphosphonate have on bone mineral density within each treatment group, in women with osteopenia or osteoporosis?
Population: 497 postmenopausal women with hormone-receptor-positive breast cancer. Two subgroups were identified: (1) Those with baseline T-scores of -2.0 or greater at the spine and hip, with no osteopenia or osteoporosis, those that had not taken bisphosphonates within the 6 months prior to registration [n=300]; and (2) Those with baseline T-scores less than -2.0, who had either started or continued treatment with bisphosphonates at registration, and had had a creatinine clearance of >35 mL/min [n=197]. All study patients were prescribed daily doses of calcium (1000 mg) and vitamin D (800 IU).
Intervention: Exemestane: Patients in this group received exemestane 25 mg as an adjuvant treatment daily for 5 years. 147 women received this intervention in subgroup 1 (i.e. baseline T-scores of -2.0 or greater), (median age [IQR]: 63.2 [58.1-70.9]). 101 women underwent this intervention in subgroup 2 (i.e. baseline T-scores less than -2.0), (median age [IQR]: 68.3 [61.1-73.7]).
Comparison: Anastrozole: Patients in this group received anastrozole 1 mg as an adjuvant treatment daily for 5 years. 153 women underwent this intervention in subgroup 1 (median age [IQR]: 62.0 [57.1-68.2]). 96 women were administered this intervention in subgroup 2. (median age [IQR]: 71.0 [61.9-77.0]).
Outcomes: Outcomes included bone mineral density (BMD) of the lumbar spine and hip (as assessed by dual-energy x-ray absorptiometry [DEXA]), serum bone turnover and formation markers, as well as the incidence of fracture.
Methods: RCT; Multi-Centre: Non-Blinded/ Open-Label
Time: T-scores were calculated at 1 and 2 years.
What were the important findings?
What should I remember most?
How will this affect the care of my patients?
The authors responsible for this critical appraisal and ACE Report indicate no potential conflicts of interest relating to the content in the original publication.