Abstract P2-08-08: A population-based study examining the epidemiology, treatment patterns and resource utilization by stage in Ontario patients with triple negative breast cancer

Background: There is limited current data on the incidence, clinical characteristics, treatment patterns, and resource utilization in breast cancer patients with a triple negative (TNBC) clinical phenotype (ER-/PR-/HER2-). Moreover, no prior publications have detailed the differences in resource use according to TNBC stage in a publicly funded healthcare setting. Methods: We retrospectively collected data for women aged 18-105 years, residing in Ontario, utilizing the public healthcare system, and diagnosed with invasive BC from Apr 1, 2012 to Mar 31, 2016. Data were extracted from datasets housed by the Institute for Clinical Evaluative Sciences. Women with triple negative pathology were identified and baseline clinical characteristics, treatment patterns, and healthcare resource utilization were descriptively compared between stage I-III and stage IV sub-cohorts. Outcomes assessed included 5-year overall survival (OS) rate by stage. Patients alive/lost to follow-up at the end of the study period (Mar 31, 2017) were censored. Unit costs (2017 CAD $) for publicly funded healthcare services were multiplied by resources used in order to calculate the total and annual health system-related costs. Results: In total, 3,271 women were identified as having TNBC; 3,081 with stage I-III and 190 with stage IV disease at diagnosis. Patients with metastatic TNBC tended to be older (63.9 ± 15.7 years) compared to those with stage I-III disease (58.8 ± 14.4 years). With a median follow-up of 34.5, 32.7, 26.2 and 8.9 mos, 5-year OS rates were 93.3%, 78.9%, 47.2% and 7.4% for stage I, II, III, and IV, respectively. Surgery was the most common treatment modality among patients with stage I-III (n=2,979, 96.7%) and least common in those with stage IV (n=16, 8.4%) disease. Among patients treated with upfront surgery for early stage disease (n=2,419, 81.2%), 1,890 (78.1%) received adjuvant systemic therapy (AT) with a median time from surgery to treatment of 45 days (IQR: 35,62). The remaining 560 patients (18.8%) with stage I-III disease received neo-AT starting a median of 28 days (IQR: 21,39) after diagnosis, with 221 (39.5%) also receiving AT. In total, 2,341 (76.0%) of patients with stage I-III BC received radiation. Among patients with metastatic TNBC, 138 (72.6%) received systemic therapy and 109 (57.4%) were treated with radiotherapy. Annual mean healthcare cost per person was $35,063.96 for stage I-III and $140,160.23 for stage IV TNBC. In both early and metastatic TNBC, cancer clinic visits, in-patient hospitalization, and professional fees were the main contributors to healthcare costs whereas pharmaceutical, home care, day surgery and continuing care contributed Conclusions: Characteristics and clinical outcomes were as expected for our Ontario-based population of women with TNBC. Our data highlights room for improvement related to wait times for surgery and initiation of systemic therapy in patients with early stage TNBC; an important endeavour considering the aggressiveness of this disease. Despite receiving fewer treatment interventions (surgery, pharmacologic and/or radiation), patients with stage IV TNBC incurred more healthcare costs per person than those with earlier stage disease. These data illustrate the treatment patterns and resource utilization for women with TNBC in Ontario and highlight opportunities to improve their outcomes. Citation Format: Christine Brezden-Masley, Kelly Elizabeth Fathers, Megan Coombes, Cloris Xue, Behin Pourmirza, Katarzyna J. Jerzak. A population-based study examining the epidemiology, treatment patterns and resource utilization by stage in Ontario patients with triple negative breast cancer [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 P2-08-08.