Authors: Fiona M McCaig Lorna Renshaw Linda Williams Oliver Young Juliette Murray Elizabeth J Macaskill Mary McHugh Rosemary Hannon J Michael Dixon
Publish Date: 2009/11/26
Volume: 119, Issue: 3, Pages: 643-651
Abstract
ALIQUOT Anastrozole vs Letrozole an Investigation of Quality Of Life and Tolerability was a prospective openlabel randomized pharmacodynamic study designed to assess the effects of aromatase inhibitors AIs on bone turnover in healthy postmenopausal women with estrogen receptorpositive breast cancer Ninetyfour patients were randomized to receive either 12 weeks of letrozole 25 mg n = 42 followed by 12 weeks of anastrozole 1 mg or 12 weeks of anastrozole 1 mg n = 42 followed by 12 weeks of letrozole 25 mg After completion of the study period patients in the immediate adjuvant group were either switched to tamoxifen n = 38 or continued on anastrozole or letrozole In the beginning of the study 42 patients had taken tamoxifen within 3 months Patients taking drugs likely to affect bone metabolism including bisphosphonates were excluded Eightyfour patients had complete sample measurements and were included in the analysis Prior tamoxifen therapy resulted in a significantly lower mean baseline procollagen type 1 Nterminal propeptide PINP compared with patients with no prior tamoxifen There were no significant differences in bone markers between AIs at any time By 6 months significant increases were seen in PINP Cterminal telopeptides CTX bone specific alkaline phosphatise ALP and urinary Nterminal telopeptides NTX Patients with prior tamoxifen had significantly greater increases than patients with no prior tamoxifen Patients treated with 3 months of tamoxifen following 6 months of an AI showed a significant decrease in markers of bone resorption serum CTX and urinary NTX In conclusion AIinduced bone turnover increases over time Anastrozole and letrozole produce similar effects on bone metabolism and turnover Stopping tamoxifen therapy and starting AIs results in a significantly greater increase in bone turnover compared with commencing AIs in tamoxifennaïve patients Patients given tamoxifen following AI therapy showed a decrease in markers of bone resorptionWhere/when study was presented in part elsewhere San Antonio Breast Cancer Symposium December 13–16 2007 San Antonio TX in poster format the European Breast Cancer Conference April 15–19 2008 Berlin as an oral presentation the Association of Surgeons of Great Britain and Ireland Surgical Meeting ASGBI May 14–16 2008 Bournemouth UK as an oral presentation
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