Influence of Comorbidities and Age on Risk of Death Without Recurrence: A Retrospective Analysis of the Arimidex, Tamoxifen Alone or in Combination Trial

Abstract

Purpose The Arimidex, Tamoxifen Alone or in Combination (ATAC) study was a double-blind randomized trial in which postmenopausal women with early-stage breast cancer were assigned to receive anastrozole, tamoxifen, or the combination. We have conducted a retrospective analysis to examine the effects of comorbidities and age on treatment received, breast cancer–related mortality, and competing causes of mortality. Patients and Methods The current analyses were based on 10-year median follow-up data in the two monotherapy arms (anastrozole, n = 3,092; tamoxifen, n = 3,094) of the ATAC study. Baseline comorbidities and tumor and treatment characteristics were compared between women age less than 70 years and women age ≥ 70 years. The cumulative incidence of breast cancer–related and non–breast cancer–related mortality was assessed according to age and comorbidities. Results One thousand six hundred sixty-two patients (27%) were age ≥ 70 years at study entry. Older women were more likely to undergo mastectomy (odds ratio [OR], 1.92; 95% CI, 1.71 to 2.16) and less likely to receive radiotherapy (OR, 0.49; 95% CI, 0.44 to 0.55) or chemotherapy (OR, 0.24; 95% CI, 0.18 to 0.29). Women age ≥ 70 years had an increased risk of recurrence compared with women age less than 70 years (hazard ratio [HR], 1.21; 95% CI, 1.08 to 1.37) and a substantially increased risk of death without recurrence (HR, 4.13; 95% CI, 3.53 to 4.83). The risk of death without recurrence increased with comorbidity score (10-year estimates of 8.4%, 20.0%, and 30.4% for Satariano score 0, 1, and 2+, respectively; P < .001). Conclusion Age influences the risk of recurrence, and age and comorbidities significantly influence the risk of death without recurrence. Formal assessment of comorbidities should be incorporated into decisions regarding adjuvant therapies.