Abstract GS6-04: Development and validation of a chemotherapy toxicity (Chemo Tox) risk score for older patients (Pts) with breast cancer (BC) receiving adjuvant/neoadjuvant treatment (Adjuvant Tx): A R01 and BCRF funded prospective multicenter study

Background: Older pts with BC receiving adjuvant tx are at increased risk of chemo tox; however, no BC-specific tool exists to quantify this risk. The Cancer and Aging Research Group (CARG) developed/validated a chemo tox score for older pts with all stages of solid tumor. The goals of this study were to: 1) build upon the CARG score by developing/validating CARG-BC (a BC specific adjuvant chemo tox score for older pts) and 2) evaluate its association with dose modifications, reduced relative dose intensity (RDI) and hospitalizations. Methods: 501 pts age ≥65 with stage I-III BC from 16 sites were accrued (300 development; 201 validation cohort). A pre-chemo assessment captured: CARG chemo tox score, BC tumor/tx variables, and additional geriatric assessment (GA) items. Grade 3-5 chemo tox by NCI CTCAE v 4.0 was captured. Univariate analysis identified chemo tox risk factors (p Results: Among 501 pts, 28 received non-standard regimens and were excluded, leaving 473 evaluable pts: 283 development and 190 validation cohort. The development cohort (median age 70; range 65-85) had Stage I (39%), II (41%), & III (20%) BC with 65% hormone positive, 24% triple negative, 27% Her2 positive; and 37% received an anthracycline. Grade 3-5 tox occurred in 46% (36% grade 3, 10% grade 4, 0.4% grade 5). The CARG score was significantly associated with grade 3-5 tox (p Conclusions: We developed and validated a risk score (CARG-BC) which identifies an older pt9s risk for adjuvant BC chemo tox and is associated with dose reduction, delay, reduced RDI, and hospitalization. This tool could be considered as a part of adjuvant tx decision-making. Citation Format: Hurria A, Magnuson A, Gross CP, Tew WP, Klepin HD, Wildes TM, Muss HB, Dotan E, Freedman R, O9Connor T, Dale W, Cohen HJ, Katheria V, Arsenyan A, Levi A, Kim H, Sun C-L. Development and validation of a chemotherapy toxicity (Chemo Tox) risk score for older patients (Pts) with breast cancer (BC) receiving adjuvant/neoadjuvant treatment (Adjuvant Tx): A R01 and BCRF funded prospective multicenter study [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr GS6-04.