Quality of life of postmenopausal women in the ATAC ("Arimidex", tamoxifen, alone or in combination) trial after completion of 5 years' adjuvant treatment for early breast cancer

The impact of treatment on health-related quality of life (HRQoL) is an important consideration in the adjuvant treatment of operable breast cancer. Here we report mature HRQoL outcomes from the ATAC trial, comparing anastrozole with tamoxifen as primary adjuvant therapy for postmenopausal women with localized breast cancer. Patients completed the Functional Assessment of Cancer Therapy-Breast (FACT-B) questionnaire plus endocrine subscale (ES) at baseline, 3 and 6 months, and every 6 months thereafter. Baseline characteristics in the HRQoL sub-protocol were well balanced between the anastrozole (n = 335) and tamoxifen (n = 347) groups in the primary analysis population. As with previously published results at 2 years, there was no statistically significant difference in the Trial Outcome Index of the FACT-B, the primary endpoint of the study, between treatments at 5 years. There were no statistically significant differences between treatment groups in ES total scores. Consistent with the 2-year analysis, there were differences between treatment groups in patient-reported side effects: diarrhea (anastrozole 3.1% vs. tamoxifen 1.3%), vaginal dryness (18.5% vs. 9.1%), diminished libido (34.0% vs. 26.1%), and dyspareunia (17.3% vs. 8.1%) were significantly more frequent with anastrozole compared to tamoxifen. Dizziness (3.1% vs. 5.4%) and vaginal discharge (1.2% vs. 5.2%) were significantly less frequent with anastrozole compared to tamoxifen. In this, the first report of HRQoL over 5 years of initial adjuvant therapy with an aromatase inhibitor, we conclude that anastrozole and tamoxifen had similar impacts on HRQoL, which was maintained or slightly improved during the treatment period for both groups.