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In Reply:

University of Arkansas for Medical Sciences, Little Rock, AR
Pfizer Inc, New London, CT

We thank Dr Panasci for his comments. The results in our article for receptor positive cancers show a highly significant effect of tamoxifen on the hazard ratio for disease-free survival (DFS).¹ While there is only a marginally significant effect for overall survival (OS), the hazard ratio for OS is similar to that of DFS. This indicates that the significance is primarily attributable to the number of events observed. It is correct that the observed difference at 10 years is only 3%, though the confidence interval on this difference would be wide. The hazard ratio is the preferred measure of effect since it utilizes data over the entire time period and is adjusted for prognostic factors. It must also be noted that tamoxifen treatment ends after 5 years, so that one might expect the effect to be attenuated at 10 years. This effect is confirmed by plots of the actual hazard rates that show the advantage of tamoxifen in hormone receptor-positive patients dissipates at 10 years.

Although the estimated difference at the single 10-year time point is the same, the hazard ratio estimate is better for tamoxifen (1.26) than for cyclophosphamide, doxorubicin, and fluorouracil (1.19), so the observed results are not identical. Improvements in the magnitude of 1.25 are considered worthwhile in breast cancer, particularly for less toxic agents.

The article does, in fact, indicate the two-sided test at this analysis is .06. However, considering the consistency across analyses over time (DFS, OS, and interaction tests all significant by design criteria at all three analysis times and all, but one of the 12 tests significant by two-sided testing as well), our conclusions would not seem unreasonable.

Authors' Disclosures of Potential Conflicts of Interest

The authors indicated no potential conflicts of interest.

REFERENCE

1. Hutchins LF, Green SJ, Ravdin PM, et al: Randomized, controlled trial of cyclophosphamide, methotrexate, and fluorouracil versus cyclophosphamide, doxorubicin, and fluorouracil with and without tamoxifen for high risk, node-negative breast cancer: Treatment results of Intergroup protocol INT-0102. J Clin Oncol 23:8313-8321, 2005[Abstract/Free Full Text]

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Related Correspondence

• Effect of Tamoxifen After Chemotherapy in Hormone Receptor–Positive, Node-Negative Breast Cancer
  Lawrence C. Panasci
  JCO 2006 24: 2392 [Full Text]

This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Alert me to new issues of the journal Save to my personal folders Download to citation manager Rights & Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Hutchins, L. F. Articles by Green, S. J. Search for Related Content PubMed Articles by Hutchins, L. F. Articles by Green, S. J. Related Articles Related Correspondence Social Bookmarking                            What's this?