Abstract P3-08-40: Prognostic factors associated with clinical outcomes in HR+, HER2- advanced breast cancer: Systematic literature review

Background Advanced breast cancer (ABC) is a heterogeneous disease with several well-defined subtypes, among which, HR+, HER2- is the most prevalent. While clinical factors and genomic signatures have clear prognostic significance in the early breast cancer setting, this is less clear in the advanced disease setting. The aim of this systematic literature review was to identify the strength and consistency of evidence for prognostic factors in HR+, HER2-, ABC patients. Methods A comprehensive search was conducted of the major electronic databases (MEDLINE, EMBASE and Cochrane Controlled Register of Trials) in November 2018 for primary research clinical studies published since 2010 in HR+, HER2- ABC patients. Endpoints of interest were tumor response, progression-free survival (PFS), overall survival (OS), and breast-cancer specific survival (BCSS). Studies were screened by two independent reviewers for eligibility. Results Seventy-nine studies (72 full-text publications and 7 conference abstracts) were included wherein all patients were diagnosed with ABC and ≥50% of the population were HR+, HER2-. The majority were observational studies (n=71). Among the four endpoints, OS was the most commonly (n=67) assessed. Negative progesterone receptor (PR) status, higher tumor grade, higher CTC count, higher Ki67 level, number of metastatic sites (multiple vs. single) and sites of metastases (e.g., presence of liver metastases vs. absence), patients with relapsed BC compared with de novo metastatic BC, shorter time to recurrence or progression to ABC, poor performance status, prior therapy attributes in the early or metastatic setting (type of therapy, treatment line, response of prior therapy), and race (black vs. white) were consistently (>50% of studies found significant association) associated with worse OS; the relationship was inconsistent for tumor size, histological type (lobular vs. ductal), lymph node involvement and age. Directionality of relationship was consistent for all factors except lymph node involvement. Strength of association with OS was moderate [hazard ratio (HR) between 1.5-2.9] for PR status, tumor grade, CTC count, and Ki67 level, number and site (e.g., bone, liver, lung) of metastases, time to recurrence or progression to ABC, performance status, prior therapy attributes, and weak (HR Citation Format: Gebra C Carter, Keri Stenger, Maitreyee Mohanty, Amy L Chong, Pradeep Basa, Shivaprasad Singuru, Sheena Singh, Vanita Tongbram, Sherko Kummel, Valentina Guarneri, Sara M Tolaney. Prognostic factors associated with clinical outcomes in HR+, HER2- advanced breast cancer: Systematic literature review [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 P3-08-40.