Women taking the anti-breast cancer drug exemestane (Aromasin) should have regular bone monitoring to assess fracture risk because the treatment speeds up loss of bone density, a study suggests.
A total of 4,500 healthy post-menopausal women from families with a history of breast cancer took part in the study to determine the effectiveness of the drug.
The drug, which is an aromatase inhibitor and so reduces levels of oestrogen which some breast cancers feed off to grow, was extremely effective, cutting the risk of breast cancer by nearly two-thirds.
But a sub-study by bone specialists from Canada measured the bone density of 351 of the women, who were either on exemestane (Aromasin) or a placebo.
Those taking the drug suffered a high loss of bone density at the distal radius, a common fracture point in the wrist, as well as at the lower end of the tibia.
There was also an 8% reduction in the thickness of their bone’s protective outer shell, the cortical bone.
Lead study author Angela Cheung, of Toronto’s University Health Network, said that as well as regular bone monitoring, such patients should also have sufficient calcium and vitamin D supplements to tackle the increased fracture risk.
- Cheung A. et al, Bone density and structure in healthy postmenopausal women treated with exemestane for the primary prevention of breast cancer: a nested substudy of the MAP.3 randomised controlled trial. Lancet Oncology (2012) DOI:10.1016/S1470-2045(11)70389-8