The impact of non- and anthracycline-based chemotherapy on fatigue in breast cancer survivors: results from WF-97415

To examine the differential effect of non- and anthracycline-based chemotherapy on fatigue over 12 months post-diagnosis among breast cancer survivors. This study is based on a prospective Wake Forest NCI Community Oncology Research Program (NCORP) multicenter cohort study (WF-97415) of women with stage I to III breast cancer and non-cancer controls. Analyses compared those: 1) receiving, or 2) not receiving anthracycline chemotherapy, 3) receiving aromatase inhibitors (AIs) without chemotherapy, with 4) a comparator group without a history of cancer. In-person clinic assessments were conducted at: baseline (prior to chemotherapy or start of AI therapy), and 3 and 12 months after baseline. The Functional Assessment of Chronic Illness Therapy-Fatigue scale was the primary outcome. Estimated least squares means by group using mixed models with a random subject effect, fixed effects of time and group, and the interaction between time and group was used to compare groups across time, controlling for age, comorbidities, and treatment variables. Among 284 women (mean age = 53.4 years, sd 11.9 years), there was a significant (p < 0.0001) group by time interaction, with a sharp increase in fatigue at 3 months in the two chemotherapy groups in comparison to the non-chemotherapy and non-cancer controls. The two chemotherapy groups did not significantly differ in fatigue at any time point. Women with breast cancer who receive non- or anthracycline-based chemotherapy experience similar trends in and levels of fatigue within the first year of treatment and greater fatigue than women receiving AIs alone or women without breast cancer.