Canadian Cancer Trials Group Bulletins

Group Administrators Office

Recent Publication

There was one recent publication reporting primary results of Canadian Cancer Trials Group MA.27B - The Influence of Five Years of Adjuvant Anastrozole or Exemestane on Bone Mineral Density in Postmenopausal Women with Primary Breast Cancer. A Companion Study to MA.27.

Canadian Cancer Trials Group MA.27 was an open-label, phase 3, randomised controlled trial in which women with breast cancer were assigned to one of two adjuvant oral aromatase inhibitors -- exemestane or anastrozole. The authors postulated that exemestane -- a mildly androgenic steroid -- might have a less detrimental effect on bone than non-steroidal anastrozole. In this companion study to MA.27, changes in bone mineral density (BMD) in the lumbar spine and total hip between patients treated with exemestane were compared with those patients treated with anastrozole.

MA.27B recruited two groups of women from MA.27: those with BMD T-scores of −2.0 or more (up to 2 SDs below sex-matched, young adult mean) and those with at least one T-score (hip or spine) less than −2.0. Both groups received vitamin D and calcium; those with baseline T-scores of less than −2.0 also received bisphosphonates. The primary endpoints were percent change of BMD at 2 years in lumbar spine and total hip for both groups.

Patients with baseline T-score of −2.0 or more taking exemestane had two fragility fractures and two other fractures, those taking anastrozole had three fragility fractures and five other fractures. For patients who had baseline T-scores of less than −2.0 taking exemestane, one had a fragility fracture and four had other fractures, whereas those taking anastrozole had five fragility fractures and one other fracture.

The authors conclude that adjuvant treatment with aromatase inhibitors can be considered for breast cancer patients who have T-scores less than −2.0.

Goss PE, Hershman DL, Cheung AM, Ingle JN, Khosla S, Stearns V, Chalchal H, Rowland K, Muss HB, Linden HM, Scher J, Pritchard KI, Elliott CR, Badovinac-Crnjevic T, St Louis J, Chapman JA, Shepherd LE. Effects of adjuvant exemestane versus anastrozole on bone mineral density for women with early breast cancer (MA.27B): a companion analysis of a randomised controlled trial. The Lancet Oncology 15: 474-82, 2014.