Comorbidity, chemotherapy toxicity, and outcomes among older women receiving adjuvant chemotherapy for breast cancer (BC).

Abstract

6015 Background: Comorbidity increases with age. We evaluated how comorbidity was associated with toxicity and clinical outcomes among older women with BC who received adjuvant chemotherapy. Methods: Cancer and Leukemia Group B (CALGB 49907) enrolled 633 women ≥65 years with early stage BC and randomized them to standard adjuvant chemotherapy (AC or CMF) or capecitabine (N Eng J Med 360:2055, 2009). 329 women on the Quality of Life companion study completed a pre-treatment health survey (Older American Resources and Services Questionnaire, physical health subscale). The survey evaluates 14 conditions and the degree to which each interferes with daily activities (rated from 1 “not at all” to 3 “a great deal”). Comorbidity was analyzed as follows: 1) total number 2) comorbidity burden score (summed conditions multiplied by interference rating); and 3) individual diseases. Primary outcomes were: 1) grade 3-5 toxicity (incident and cumulative); 2) time to relapse (TTR), and 3) overall survival (OS). Contingency table methods were used to evaluate the association between comorbidity and toxicity. Cox proportional hazards models were used to evaluate TTR and survival outcomes. Results: Among 329 women [median age 71 years (range 65-89), 86% white, 98% ECOG performance score 0-1, 75% stage 1-2] the median number of comorbidities was 2 (0-10), median comorbidity burden score was 3 (0-25), and most common conditions were arthritis (58%) and hypertension (54%). Few patients had diabetes (17%), heart disease (16%), and pulmonary disease (9%). No comorbidity measure was associated with toxicity or TTR. With a median follow-up of 5.4 years, increasing comorbidity was associated with shorter OS. For each additional comorbid condition the hazard of death increased by 18% (HR 1.18 [95% CI; 1.06-1.33]) after adjusting for age, tumor size, treatment, node status and receptor status. Comorbidity burden score was similarly associated with OS (HR 1.08 [95% CI; 1.03-1.14]), while no specific condition was independently associated. Conclusions: Among older women with good functional status, comorbidity was not associated with toxicity or BC relapse. However, comorbidity burden was associated with shorter OS.