Higher cardiac events from letrozole...

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Letrozole or Tamoxifen in Early Breast Cancer

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Related Articleby The Breast International Group (BIG) 1-98 Collaborative GroupFind Similar ArticlesPubMed CitationTo the Editor: The report on the Breast International Group (BIG) 1-98 trial (Dec. 29 issue)1 highlights apparently statistically nonsignificant data from subgroups (of patients who had received previous chemotherapy and those who had node-positive disease) and contrasts them with the results of the Arimidex, Tamoxifen, Alone or in Combination (ATAC) trial.2 We believe that clinical decisions should not be based on subgroup analyses3 when there are no clear reasons for a differential effect of treatment and no statistical evidence of interaction or heterogeneity. (Such test results were not observed in the ATAC trial2 and not reported in the BIG 1-98 trial, although it is unlikely such tests were performed, given the results shown in Figure 3 of the article.)

We would be interested in knowing the rate of withdrawal due to adverse events in the BIG 1-98 trial. More patients who received letrozole reported at least one adverse event than did patients who received tamoxifen. In the ATAC trial, there were significantly fewer adverse events with anastrozole than with tamoxifen, both overall events and those resulting in withdrawal from the study.2

We agree that the significantly higher risk of cardiac events of grades 3 to 5 and the higher number of deaths from cardiac or cerebrovascular causes in the letrozole group than in the tamoxifen group require further study. However, we do not believe that the evidence indicates an increased risk of cardiovascular events with all aromatase inhibitors. Mature data from the ATAC trial have shown no increased risk of myocardial infarction or deaths from cardiovascular causes among patients receiving anastrozole, as compared with those receiving tamoxifen.2,4


Aman U. Buzdar, M.D.
University of Texas M.D. Anderson Cancer Center
Houston, TX 77030
abuzdar@mdanderson.org


Michael Baum, M.D.
University College London
London WIP 7LD, United Kingdom


Jack Cuzick, Ph.D.
Wolfson Institute of Preventive Medicine
London EC1M 6BQ, United Kingdom

Dr. Buzdar reports having received honoraria and research funding from AstraZeneca and research funding from Eli Lilly, Pfizer, Genentech, and Taiho Pharmaceutical. He reports currently serving as chair of the ATAC Steering Committee, which is partly funded by AstraZeneca. Dr. Baum reports having received honoraria and consulting fees from AstraZeneca and was the founding chair of the ATAC Steering Committee. Dr. Cuzick reports having received honoraria from AstraZeneca and is an independent biostatistician for the ATAC trial. References