Abstract PO4-11-01: Validation of a CARG-BC-based score for the prediction of therapy-induced toxicities in patients with metastatic breast cancer

Abstract Introduction Prediction of treatment-induced toxicities is important in order to tailor and adjust oncologic therapies. As limited tools exist to predict the risk of therapy-induced toxicities in patients with metastatic cancer, we aimed to develop and to validate a score for the prediction of therapy-induced toxicities in patients with metastatic breast cancer treated with chemotherapy and immunotherapy. The score was based on the Cancer and Aging Research Group-Breast Cancer early-stage breast cancer score for prediction of chemotherapy-induced toxicities. Methods All patients treated for metastatic breast cancer with chemotherapy and immunotherapy at the Department of Gynecology, Obstetrics and Reproductive Medicine at Saarland University Hospital between 01/2014 and 05/2022 were included in this retrospective study. Patient characteristics and therapy-relevant oncological parameters were recorded, as well as therapy-induced toxicities (recorded according to CTC), hospitalization rates, toxicity-related dose reductions and therapy discontinuations. In the first cohort (development cohort), a new score for the prediction of therapy-induced toxicities was developed using ROC analysis and multivariate analysis based on the CARG-BC score. In the second cohort (validation cohort), this was validated using Pearson’s correlation coefficient. Results Data from 32 patients were analyzed for the development cohort, and inclusion of 102 patients contributed to the validation cohort. The newly developed score consists of seven independent factors for the prediction of toxicities ≥ CTC III° and includes the parameters “presence of visceral metastases” (yes/no), “received previous lines of therapy” (yes/no), “limited mobility/able to walk less than one kilometer” (yes/no), “a fall in the last six months” (yes/no), “social interactions” (yes/no), “pretherapeutic change of transaminases” (yes/no) and “pretherapeutic change of hemoglobin” (hemoglobin / 10 g/dl). Based on the results, three risk groups were defined (low (0-2), medium (3-5) and high (6-15) risk). 28% of patients were in the low-risk group, 37% in the intermediate-risk group and 34% in the high-risk group. Overall, 49% of the patients had toxicities ≥ CTC III°. Distributed across the subgroups, these occurred in 14% in the low-risk group, 34% in the intermediate-risk group and in 52% in the high-risk group (p ≤ 0.01). Risk score results showed a correlation with treatment discontinuation and hospitalization rate (p ≤ 0.01), but not with dose reduction (p = 0.77). Conclusion The available data show a correlation between the risk score results and the occurrence of systemic therapy-induced toxicities in patients with metastatic breast cancer. The results can be used to further identify risk populations and to systematically apply preventive and supportive measures in order to approve quality of life in patients with metastatic breast cancer. Citation Format: Julia SM Zimmermann, Aylin Aygün, Askin Kaya, Marc P Radosa, Christoph G Radosa, Erich F Solomayer, Julia C Radosa. Validation of a CARG-BC-based score for the prediction of therapy-induced toxicities in patients with metastatic breast cancer abstract. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-11-01.