This study explored age as a moderator for the association between treatment modifications and survival in Black women with early stage breast cancer. The sample consisted of 115 Black women treated with adjuvant chemotherapy. Results indicate that older Black women with chemotherapy doses held experienced worse disease-free survival than those who did not. Background: Black women receive less relative dose intensity with more dose reductions and early chemotherapy cessation compared with White women. Adding further risk, older patients with breast cancer are most at risk for treatment modifications; however, it is unclear if this remains true for Black patients. Furthermore, the clinical implications of treatment modifications and delays on survival is uncertain, particularly in Black patients. Patients and Methods: The purpose was to investigate whether age was a moderator for the association between treatment modifications (dose held, dose delayed, and early cessation) and overall survival and disease-free survival (DFS) in Black women with breast cancer using a retrospective cohort study of patients with early stage breast cancer treated with adjuvant chemotherapy. Results: Across the entire sample (n = 115), 37.4% (n = 43) of patients experienced a treatment modification. There was a significant interaction between age group and held dose for DFS (P = .026). Specifically, those diagnosed at 55 years of age and older, who had doses of chemotherapy held, experienced worse DFS compared with those who did not (hazard ratio, 4.185; 95% confidence interval, 1.187-14.75). In contrast, there was no difference in DFS between those who did and did not have doses held in patients diagnosed below 55 years of age (hazard ratio, 0.626; 95% confidence interval, 0.177-2.218). Conclusion: In this study, Black women receiving adjuvant chemotherapy for treatment of early stage breast cancer had roughly equal treatment modifications across age groups. However, held doses of chemotherapy in older Black patients were associated with worse DFS. Age may impact clinical outcomes seen with adjuvant chemotherapy treatment modifications. (C) 2019 Elsevier Inc. All rights reserved.