Response

Extract

We appreciate the interest of Drs. Panasci and Melnychuk in our article and understand their concerns with regard to the necessity to determine a survival advantage from tamoxifen. The overall survival curve shown in our article indicates that survival distributions in the two groups were within 1% at 8 years. However, the difference in survival that begins to emerge at 4 years results in a significant survival benefit cumulatively through 10 years.

Our primary purpose in showing treatment comparisons by age was to illustrate the consistency in response among younger and older patients, since, for some time, there has been concern about the efficacy of tamoxifen in premenopausal women. Our statement that the interaction between treatment response and age group was nonsignificant ( 1 ) indicates the absence of statistical evidence of a difference in reduction in mortality by age group for patients receiving tamoxifen. Although the B-14 study included a very large number of patients, the ability to detect statistically significant differences in survival rates among groups is determined by the number of deaths observed. We would expect that, examining subgroups of patients who have insufficient events to provide adequate statistical power for reliable comparisons, nonsignificant results may be obtained.