Abstract PO1-03-06: Older patients with Early Stage Triple Negative Breast Cancer: The Memorial Sloan Kettering Cancer Center experience

Abstract INTRODUCTION Approximately 15% cases of TNBC are diagnosed in individuals over the age of 70. Older patients remain under-represented in clinical trials. We conducted a retrospective review of patients 70 years of age and older with stage I-III TNBC who were treated at Memorial Sloan Kettering Cancer Center (MSKCC), with the goal of describing the clinical practice patterns and outcomes. MATERIAL AND METHODS A retrospective record review of patients 70 years of age and older with a diagnosis of stage I-III TNBC between January 2015-December 2019 was performed. We report the data on the utilization of systemic chemotherapy and survival analyses. We compared patient characteristics by chemotherapy type using Wilcoxon rank sum test, Pearson’s Chi-squared test, and Fisher’s exact test. Overall Survival (OS), Breast Cancer Specific Survival (BCSS), and Recurrence Free BCSS (RF-BCSS) were examined using Cox proportional hazards models. All statistical analyses were conducted using R. RESULTS A total of 147 patients were included. The median age was 75 years (range 70-96). The number of patients with stage I, II, and III disease was 64 (44%), 66 (45%), 17 (12%), respectively. Twenty-five (18%) patients underwent comprehensive geriatric assessment. Out of total patients, 93 (63%) patients received systemic Chemotherapy (C) while 54 (37%) received no chemotherapy (NC). Patients receiving C were younger (median age 74 years with C vs. 78 years with NC, p 0.001) and had a higher disease stage (Stage II-III: 66% (C) vs. 41% (NC), p=0.005). There were no significant differences in Activities of Daily Living (ADL) difficulty between both arms. Amongst, Instrumental ADL (IADL) assessment, patients in the NC group reported statistically significant greater difficulty with meal preparation (17% in NC and 4.3% in C, p=0.016). The most common reasons for not receiving chemotherapy were low-risk disease i.e. pT1aN0 or microinvasive (33%), patient preference (29%), and frailty per the treating oncologist (19%). Rate of mastectomy was higher in the NC group (35% in NC vs. 20% in C, p=0.029). Among the 32 patients who had radiation data, breast irradiation rates were higher in the C group (70% in C and 17% in NC, p=0.003). Thirty patients (20%) received neoadjuvant chemotherapy (NAC) and 65 (44%) received adjuvant chemotherapy. Anthracycline-based chemotherapy was the most common NAC (n=17, 57%). Patients who received Cyclophosphamide-Methotrexate-5-Fluorouracil (CMF) were older (age ≥75 years: 51% (CMF) vs. 17% (ACT),p=0.010), more likely treated in an adjuvant setting (87% CMF vs. 61% ACT, p=0.017), had earlier-stage disease (Stage 1: 54% (CMF) vs. 26% (ACT), p=0.028), and reported more ADL (31% in CMF vs. 0% in ACT, p=0.002) and IADL difficulties (31% CMF vs 4.3% in ACT, p=0.021). The use of Docetaxel/Cyclophosphamide (TC) and platinum-based regimens was low (8% and 5%, respectively). In the univariate analysis between the C and NC groups, there was no difference in OS (Hazard Ratio (HR) 0.78, 95% Confidence Interval (CI) 0.42-1.43; p=0.4), BCSS (HR 1.39, 95% CI 0.57-3.39; p=0.5), and RF-BCSS (HR 1.60, 95% CI 0.67-3.83; p=0.3). There was no difference in OS (HR 0.60, 95% CI 0.23-1.55; p=0.3), BCSS (HR 0.48, 95% CI 0.17-1.32; p=0.2), and RF-BCSS (HR 0.71, 95% CI 0.30-1.73; p=0.5) in patients receiving CMF vs. ACT. CONCLUSIONS In our single institutional experience, we observed that two-thirds of older patients with early-stage TNBC received systemic polychemotherapy. A third of patients with NC were very low risk (pT1a or microinvasive disease) which could explain lack of chemotherapy benefit in our study population. Use of CMF was more prevalent in patients aged ≥75, stage I disease, ADL/IADL difficulties, and in the adjuvant setting. We observed no difference in survival outcomes between the two chemotherapy regimens. CMF remains an efficacious option and a potentially viable alternative to ACT in TNBC, especially in the setting of early stage and advanced age. Citation Format: Jasmeet Singh, Diana Lake, West Dente-Ferguson, Yuan Chen, Fiona Erlich, Beatriz Korc-Grodzicki, Mark Robson, Larry Norton, W. Iris Zhi. Older patients with Early Stage Triple Negative Breast Cancer: The Memorial Sloan Kettering Cancer Center experience 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 PO1-03-06.