Abstract P3-07-14: Increasing proportion of de novo compared with recurrent HER2-positive metastatic breast cancer: Early results from the systemic therapies for HER2-positive metastatic breast cancer registry study

Abstract

Abstract Introduction The Systemic Therapies for HER2-Positive Metastatic Breast Cancer Registry (SystHERs) is a US-based prospective observational cohort study currently enrolling patients with HER2-positive metastatic breast cancer (MBC). It began in 2012 and aims to provide real-world insight into the disease course, treatment patterns and associated clinical outcomes, and patient-reported experiences of disease. Here we describe the baseline characteristics of this population to date, including the proportion of patients with de novo and recurrent HER2-positive MBC. Methods SystHERs aims to enroll ∼1000 patients with HER2-positive MBC within 6 months of first metastatic diagnosis. At enrollment, investigators report whether patients have recurrent or de novo MBC, the latter defined as distant metastases at the time of initial MBC diagnosis. Results As of February 17, 2014, data are available from 306 of 319 enrolled patients. Forty-six percent (142/306) had de novo HER2-positive MBC. For the 54% (164/306) with recurrent HER2-positive MBC, median disease-free interval (DFI, defined here as time from early-stage breast cancer diagnosis to diagnosis of MBC) was 43.6 (range 0.5–270.2) months. For these patients with recurrent disease, 54% (89/164) received (neo)adjuvant HER2-targeted therapy. Baseline patient and tumor characteristics are shown below. CharacteristicOverall (n=306)De novo (n=142)Recurrent (n=164)Age, median (range)57 (27-86)54 (27-83)59 (30-86)Race, n (%)White233 (76)105 (74)128 (78)Black54 (18)28 (20)26 (16)Other8 (3)3 (2)5 (3)Not available11 (4)6 (4)5 (3)Ethnicity, n(%)Not Hispanic257 (84)120 (85)137 (84)Hispanic31 (10)17 (12)14 (9)Not available18 (6)5 (4)13 (8)Pre-menopausal, n (%)61 (20)42 (30)19 (12)Hormone receptor status, n (%)ER and/or PR positive209 (68)90 (63)119 (73)ER and PR negative92 (30)50 (35)42 (26)Unknown5 (2)2 (1)3 (2)Median number of metastatic sites, (range)2.0 (1-7)2.0 (1-6)2.0 (1-7)Sites of metastasis, n (%)Bone141 (46)76 (54)65 (40)Liver120 (39)63 (44)57 (35)Nodes89 (29)49 (35)40 (24)Lung87 (28)38 (27)49 (30)Chest wall43 (14)12 (9)31 (19)CNS30 (10)9 (6)21 (13) Conclusions The proportion of patients with de novo MBC appears to have increased over time to 46% in SystHERs, compared with 33% in RegistHER, a registry study that enrolled 1023 patients with HER2-positive MBC from 2003–2006 (Yardley et al, 2014), and predated the broad use of HER2-targeted therapy in the (neo)adjuvant setting. The DFI for patients with recurrent HER2-positive MBC also appears to be longer (median DFI 43.6 months in SystHERs vs. 32.6 months in registHER). We hypothesize that the proportion of patients with de novo MBC within the metastatic population is higher due to the use of advanced screening techniques which allow better detection of metastases, and due to a reduction in recurrences related to the availability of HER2-targeted adjuvant therapy. Changes in the population characteristics of patients with HER2-positive MBC may impact treatment strategies and have trial design implications. Updated data from approximately 500 patients are expected by the time of presentation. Citation Format: Debu Tripathy, Adam Brufsky, Melody Cobleigh, Mohammad Jahanzeb, Peter Kaufman, Ginny Mason, Musa Mayer, Joyce O'Shaughnessy, Hope Rugo, Sandra M Swain, Denise A Yardley, Mary Beattie, Bongin Yoo, Sara Hurvitz. Increasing proportion of de novo compared with recurrent HER2-positive metastatic breast cancer: Early results from the systemic therapies for HER2-positive metastatic breast cancer registry study [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-07-14.