Reactions 1326 - 6 Nov 2010

Anastrozole-related bone loss"manageable"

Anastrozole-related bone loss "appears to bemanageable" among women with hormone-sensitiveearly breast cancer, according to a multinational team ofresearchers.1 Thus, they contend that "any risk to bonehealth should be weighed against" the drug’s overallefficacy and tolerability profile among this patientpopulation.

The research team performed a substudy, funded byAstraZeneca, of the ATAC* trial, to examine the effects ofanastrozole and tamoxifen on bone mineral density(BMD) after 5 years of treatment. Lumbar spine and totalhip BMD measures were assessed at years 6 and 7 aftertherapy among 71 eligible patients; evaluable data wereavailable for 50 patients.

It was found that anastrozole-related bone loss didnot continue in the long-term period followingtreatment. Indeed, after anastrozole treatment, themedian lumbar spine BMD increased by 2.35% at year 6and 4.02% at year 7, while median total hip BMDincreased by 0.71% and 0.5%, respectively. Incomparison, after tamoxifen treatment, median lumbarspine BMD decreased by 0.79% at year 6 and by 0.30%at year 7, while medial total hip BMD decreased by2.09% and 2.52%, respectively.

Risks underestimated?In a related article, J-J Body from Universite Libre de

Bruxelles, Brussels, Belgium, says the above authorsargue that their findings indicate that patients withnormal BMD prior to anastrozole therapy "do not needspecific monitoring".2

However, Mr Body points out that theserecommendations "are based on a small series and donot take into account risk factors for fractures other thanBMD". He stresses that available evidence frompublished clinical studies show that "all three" third-generation aromatase inhibitors** "increase boneturnover, decrease BMD and increase fracture risk".* ‘Arimidex’, Tamoxifen, Alone or in Combination** anastrozole, exemestane, letrozole

1. Eastell R, et al. Long-term effects of anastrozole on bone mineral density:7-year results from the ATAC trial. Annals of Oncology : 7 Oct 2010. Availablefrom: URL: http://dx.doi.org/10.1093/annonc/mdq541.

2. Body JJ. Prevention and treatment of side-effects of systemic treatment: boneloss. Annals of Oncology 21 (Suppl. 7): vii180-vii185, Oct 2010. Availablefrom: URL: http://dx.doi.org/10.1093/annonc/mdq422.

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Reactions 6 Nov 2010 No. 13260114-9954/10/1326-0001/$14.95 © 2010 Adis Data Information BV. All rights reserved