Abstract P1-13-06: Impact of visceral metastases on treatment patterns for hormone-receptor-positive (HR+)/human epidermal growth factor receptor-2-negative (HER2-) metastatic breast cancer (mBC)

Abstract

Abstract Introduction: Guidelines recommend reserving chemotherapy (CT) for HR+/HER2- mBC until either endocrine-based therapy (ET) is no longer effective or for patients with visceral crisis or need for rapid tumor control. The extent to which visceral metastases (VM), regardless of whether they are contributing to visceral crisis, impact real-world treatment patterns in mBC is not well understood. This retrospective analysis characterizes treatment patterns with ET and CT among HR+/HER2- mBC patients stratified by presence of VM. Methods: Postmenopausal women (age ≥50 years) diagnosed with HR+/HER2- mBC were identified from the MarketScan® database (2002Q3-2012Q2). Patients who initiated ET without CT for mBC were followed until transition to CT, discontinuation of ET (>90 days without evidence of ET), or end of data or insurance eligibility. Upon initiation of each line of therapy, patient characteristics including age, number of metastatic sites, and presence of VM were compared between those receiving ET and those receiving CT. The number of lines of ET received before CT, and the total duration of ET were described for patients with and without VM. Results: Of the 19,120 patients who initiated treatment for mBC, 5,418 received 2nd-line treatment and 1,471 received 3rd-line treatment. In each of these 3 lines, the corresponding numbers of patients receiving CT were 7,575 (40%), 2,397 (44%) and 650 (44%). Among the patients who received CT in each line, the majority did so without evidence of VM: 5,821 (77%), 1,511 (63%) and 435 (67%), in the 1st, 2nd and 3rd lines, respectively. Within each line, the average patient receiving CT was approximately 3 to 5 years younger and had 0.02-0.29 more metastatic sites, compared with the average patient receiving ET. Among the 11,545 patients who initiated 1st-line ET, 9,315 (81%) did not have evidence of VM. Patients with versus without VM upon initiation of 1st-line ET received similar average numbers of lines of ET (1.32 versus 1.37 lines). However, the median time prior to transition to CT, discontinuation of ET, or loss to follow-up was shorter for patients with VM compared to those without VM (5 months versus 10 months). In addition, patients with VM appeared to have shorter durations of ET at each line compared with patients without VM (Table). Conclusions: Although the present analysis could not distinguish visceral crisis from the broader group of patients with visceral metastases, it is notable that a large majority of patients receiving CT did so without evidence of VM. This indicates an unmet need during the study period (2002-2012) for effective disease control among patients without VM for whom CT was not a preferred option. Table. Durations (months) of Endocrine Therapy Total number of lines of ET observed, with and without VM One LineTwo lines≥ Three linesLine of ET / patient groupVMWithout VMVMWithout VMVMWithout VMAll Patients, median (IQR)3 (1-8)6 (2-16)11 (6-23)15 (8-27)23 (14-35)26 (16-41)First line3 (1-8)6 (2-16)6 (3-15)7 (3-16)8 (3-17)9 (3-17)Second line--3 (1-6)4 (2-10)6 (3-12)5 (3-11)Third line----3 (1-5)4 (2-9)VM = visceral metastases, IQR = interquartile range Citation Format: James Signorovitch, Jenny Wang, Ruo-Ding Tan, Darren Thomason, Andrew Kageleiry, Elyse Swallow. Impact of visceral metastases on treatment patterns for hormone-receptor-positive (HR+)/human epidermal growth factor receptor-2-negative (HER2-) metastatic breast cancer (mBC) [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 P1-13-06.