I believe that Drs. Booth, Peter, and Goss in their letter are emphasizing the need to individualize the decision to extend endocrine therapy for each patient—a position that is similar to our own.1 Looking at our group as a whole, the potential benefit to extended therapy, assuming a 40% risk reduction, would have been small, in the range from 1% to 2%. However, our conclusions stated that there were subgroups that would have had more chance of benefiting from the extended therapy based on younger age or initial pathologic stage and less chance of benefiting based on older age, comorbidities, or earlier stage disease.
We reported an event-free survival rate of 7% between Years 5 and 10. Booth et al. have contrasted this with data from larger, multiinstitutional studies that had recurrence risks that ranged from 10% to 15%. However, as they point out in their letter, this may have been caused by our higher proportions of older and lymph node-negative patients. In a study of lymph node-negative patients, the National Surgical Adjuvant Breast and Bowel Project B-14 reported a recurrence-free survival rate of 94% and an overall survival rate 94% 7 years after the second randomization to placebo after 5 years of tamoxifen.2 In addition, in contrast with the MA-17 study, our study contained only patients who were eligible for breast conservation. Our group may have had smaller tumor sizes or more favorable pathologic features than studies that included patients who underwent mastectomy. Subgroups of patients in our study (see Table 21) who were younger, premenopausal at the time of diagnosis, had T2 tumor classification, or had positive lymph node status had a lower event-free survival in the 85% to 90% range, comparable to that reported for the MA-17 study. Variations in recurrence numbers are common when comparing data from single institutions with data from randomized multicenter studies or metaanalyses used in Adjuvant Online.
In conclusion, for myself and on behalf of the study authors, I believe that we share fairly common ground with little need for controversy on this issue. We agree that the decision for extended adjuvant therapy needs to be individualized. The potential risk reduction by the additional therapy needs to be gauged by the baseline risk for recurrence and weighed against patient age, comorbidities, cost, and risk of complications.