Association between age at diagnosis and disease-specific mortality among postmenopausal women with hormone receptor-positive breast cancer

Context: In addition to classic tumor-related prognostic factors, patient characteristics may be associated with breast cancer outcome. Objective: To assess the association between age at diagnosis and breast cancer outcome in postmenopausal women with hormone receptor-positive breast cancer. Design, Setting, and Patients: Study analysis of 9766 patients enrolled in the TEAM (Tamoxifen Exemestane Adjuvant Multinational) randomized clinical trial between January 2001 and January 2006. Age at diagnosis was categorized as younger than 65 years (n=5349), 65 to 74 years (n=3060), and 75 years or older (n=1357). Main Outcome Measures: Primary end point was disease-specific mortality; secondary end points were other-cause mortality and breast cancer relapse. Results: During median follow-up of approximately 5.1 years, there were a total of 1043 deaths. Disease-specific mortality, as a proportion of all-cause mortality, decreased with categorical age group (78% [<65 years], 56% [65-74 years], and 36% [≥75 years]; P < .001). In multivariable analyses, compared with patients younger than 65 years, disease-specific mortality increased with age for patients aged 65 to 74 years (hazard ratio [HR], 1.25; 95% CI, 1.01-1.54); and patients aged 75 years or older (HR, 1.63; 95% CI, 1.23-2.16) (P < .001). Similarly, breast cancer relapse increased with age for patients aged 65-74 years (HR, 1.07; 95% CI, 0.91-1.25 and patients aged 75 years or older (HR, 1.29; 95% CI, 1.05-1.60) (P=.06). Other-cause mortality increased with age in patients aged 65 to 74 years (HR, 2.66; 95% CI, 1.96-3.63) and patients aged 75 years or older (HR, 7.30; 95% CI, 5.29-10.07) (P < .001). Conclusion: Among postmenopausal women with hormone receptor-positive breast cancer, increasing age was associated with a higher disease-specific mortality.