Abstract P5-08-20: A real-world evidence study to define the prevalence of endocrine therapy-naïve hormone receptor-positive locally advanced or metastatic breast cancer in the US

Abstract

Abstract BACKGROUND The recently completed FALCON trial (NCT01602380) compared the efficacy of the selective estrogen receptor degrader (SERD) fulvestrant 500 mg with anastrozole in postmenopausal women with hormone receptor (HR)-positive locally advanced or metastatic breast cancer (LA/MBC) who had received no prior endocrine therapy (ET). To better understand the size of the US population to which the results of the FALCON trial are applicable, this study estimated the proportion of postmenopausal patients with HR-positive, human epidermal growth factor receptor (HER)2-negative LA/MBC who had received no prior ET, using data from a US medical record database. METHODS This observational study retrospectively analyzed data from the Optum Electronic Health Record Database, obtained from provider groups across the US. Women over 40 years of age with breast cancer diagnoses (January 2008–March 2015) were included, provided they had at least 12 months of recorded medical history prior to index, and at least one recorded physician office visit in that time. Incident (newly diagnosed) and prevalent (previous diagnosis of early or advanced breast cancer) cases were identified. Free-text clinical notes were reviewed using natural language processing to identify a target patient population of postmenopausal women with HR-positive, HER2-negative LA/MBC who had received no prior ET (similar to the FALCON entry criteria); additionally, diagnostic codes or treatment history were also used to identify HR status in the absence of confirmation from the free-text notes. The results of this analysis were extrapolated to estimate the size of the target population at a national level, using statistics from the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) database. Results are presented descriptively. RESULTS Overall, 63,962 women with breast cancer were identified, of whom 11,831 had discernible information on menopausal status, HER2 status, HR status, and disease stage. Of these, 1,923 patients were identified with postmenopausal, HR-positive, HER2-negative (or unknown) LA/MBC. Within this population of patients, 70.7% (1,360/1,923) had not previously received ET (88.5% [920/1,040] incident cases; 49.8% [440/883] prevalent cases), representing 11.5% (1,360/11,831) of the total breast cancer population with known menopausal status, HER2 status, HR status, and cancer disease stage information. The proportion of patients with postmenopausal, HR-positive, HER2-negative LA/MBC who had received no prior ET in this sample was extrapolated using US national estimates of the size of the postmenopausal, HR-positive, HER2-negative LA/MBC population taken from SEER. This approach suggests a 5-year limited-duration prevalence of postmenopausal patients with HR-positive, HER2-negative LA/MBC who have received no prior ET of approximately 50,000 cases and an annual incidence of about 15,000 patients. CONCLUSIONS These real-world data provide an estimate of the number of postmenopausal patients with HR-positive, HER2-negative, LA/MBC in the US who have not previously received ET. This population corresponds to the recently completed Phase 3 FALCON trial of fulvestrant compared with anastrozole. Citation Format: Nunes AP, Green E, Dalvi T, Lewis J, Jones N, Seeger JD. A real-world evidence study to define the prevalence of endocrine therapy-naïve hormone receptor-positive locally advanced or metastatic breast cancer in the US [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-08-20.