Influence of comorbidities and age on risk of death without recurrence: A retrospective analysis of the arimidex, tamoxifen alone or in combination trial

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.