Abstract PD10-10: Factors associated with decreased relative dose intensity in older adults with early-stage breast cancer receiving chemotherapy

Background: Older adults with breast cancer receiving neo/adjuvant chemotherapy are at increased risk for toxicity and dose reductions, often leading to decreased relative dose intensity (dRDI Methods: We prospectively enrolled patients aged ≥ 65 who were starting neo/adjuvant chemotherapy for HER2-negative, stage I-III breast cancer. Geriatric assessment and clinical variables were captured at baseline. Chemotherapy regimen, dosing, and treatment-related modifications (reductions, delays, discontinuation) were also captured. RDI was calculated as the ratio of actual dose delivered to intended dose. Our primary outcome was dRDI, which we defined as RDI Results: Of 323 patients (median age 69, range 65-86), 216 had HR+/HER2- breast cancer and 107 had triple negative breast cancer (TNBC). Patients were treated with taxotere and cyclophosphamide [TC] (47%), anthracycline-based regimens (46%), and cyclophosphamide, methotrexate, and 5-fluorouracil [CMF] (7%). Overall, the mean RDI was 90.1% (median 100%, range 16.7%-100%), and 69 patients (21%) had dRDI (i.e. RDI 70, higher stage (II/III), use of non-TC regimens (anthracycline-based or CMF), abnormal liver function, KPS 70 (27% dRDI, OR = 2.01, 95% CI 1.11-3.63), abnormal liver function (41% dRDI, OR = 2.50, 95% CI 1.10-5.66), and KPS Conclusion: Among older patients receiving neo/adjuvant chemotherapy for HER2-negative early-stage breast cancer, those aged > 70, treated with anthracycline or CMF regimens, with abnormal liver functions, and KPS Citation Format: Mina S Sedrak, Can-Lan Sun, Allison Magnuson, Hyman Muss, Rachel Freedman, Cary P Gross, William P Tew, Heidi Klepin, Tanya M Wildes, Efrat Dotan, Tracey O9Connor, Harvey J Cohen, Heeyoung Kim, Vani Katheria, Reena Jayani, Anait Arsenyan, Abrahm Levi, Kemeberly Charles, Arti Hurria, William Dale. Factors associated with decreased relative dose intensity in older adults with early-stage breast cancer receiving chemotherapy [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr PD10-10.