Five-year quality of life (QOL) follow-up of adjuvant endocrine therapy for postmenopausal women in the Arimidex (A), Tamoxifen (T), Alone or in Combination (ATAC) Trial

Background: The 5-year treatment completion analysis of the ATAC Trial established that compared with T, A had superior efficacy in terms of disease-free survival, time to recurrence and contralateral breast cancer with superior tolerability. The 2-year QOL data from an accompanying subprotocol involving 1021 of 9366 ATAC trial patients has already been published (JCO, 2004, 22(21):4261-4271). We report below the first results from a longitudinal follow-up of the impact of 5 years’ adjuvant hormonal therapy on QOL. Methods: QOL assessments using the FACT-B and endocrine symptom subscale (ES) were made at baseline, 3 months, 6 months, and every 6 months thereafter, up until and including confirmation of disease recurrence, cessation of trial therapy or withdrawal from the subprotocol. The primary endpoint was Trial Outcome Index (TOI), a summation of physical components of QOL. Formal analyses compared A (n=335) with T (n=347). Results: Over the 5-year period, 17% of expected evaluations were missing. The missing data rate increased with time. TOI showed continued slight improvement in both A and T groups. There was no significant difference in TOI between treatments (p=0.65). Furthermore 67% of patients in both A and T experienced a clinically meaningful TOI improvement (at least 5 pts) from baseline at some point in their follow-up. Following the initial worsening of endocrine symptoms seen at 3 months (already reported) ES stabilized, although ES never recovered to baseline levels. Overall ES showed no significant difference between A and T (p=0.51) but some differences consistent with those previously reported remained, including increased vaginal discharge and bleeding on T and increased vaginal dryness and dyspareunia on A. Conclusions: Endocrine therapy with A or T was well tolerated over 5 years of treatment. FACT-B TOI showed steady improvements, which continued beyond 2 years among women who remained on study. After an initial decrease, ES score was relatively stable until 5 years. The efficacy benefits of A are achieved without a detrimental impact on overall QOL.