Personalized estimates for a woman age 65-69 years with mild (mild comorbidity includes life expectancy associated with a history of myocardial infarction, ulcer, or rheumatologic disease) comorbidities, diagnosed with a small tumor (≤ 2 cm), and intermediate-grade breast cancer. (A) The probability distribution of 21-gene RSs; (B) 10-year risk of distant recurrence for chemoendocrine versus endocrine therapy with and without 21-gene RS test results; (C) absolute chemotherapy benefit on 10-year risk of distant recurrence with and without 21-gene RS test results; and (D) average life-years (life-years calculated considering breast cancer–specific mortality conditional on treatment, tumor grade, tumor size, age, and 21-gene RS; and other-cause mortality conditional on age and comorbidity level) gained for chemoendocrine versus endocrine therapy with and without 21-gene RS test results. RS, recurrence score.