Abstract PS7-69: Molecular profiles and clinical-pathological features of Asian early-stage breast cancer patients

Background/Objective: Breast cancer incidence in Asian populations has increased in recent years, and variation in prognosis and tumor subtypes indicates that further study is warranted to characterize these differences and identify actionable targets. Patients of Asian ancestry are underrepresented in US registries, and few studies have characterized molecular profiles for these patients. In the current analysis, we assess clinical, pathological, and molecular profiles from self-reported Asian breast cancer patients (AS), in comparison with age-matched Caucasian (CA) and African American patients (AA), to evaluate the influence of Asian ancestry on differential gene expression in breast tumors. Methods: This meta-analysis included cohorts of self-reported AS, CA, and AA with early-stage, invasive breast cancer (EBC) prospectively enrolled in the US from 2011 to 2020 in FLEX (NCT03053193), MINT (NCT01501487), or IMPACt (NCT02670577) trials. AS were significantly younger (mean, 55 years) than CA (mean, 61 years, p ± 0.5 were considered significant. Results: AS tumors were classified as 59% MP HR, compared with 44% HR in age-matched CA (p=0.08) and 64% HR in age-matched AA (p=0.17). AS had a significantly lower rate of obesity (16%, body mass index ≥30) compared with CA (41%) and AA (67%) (p Conclusions: AS were significantly younger and more often pre/peri-menopausal at diagnosis compared with CA and AA, consistent with the literature. Most clinical-pathological factors were similar between age-matched groups, except for the obesity rate, which was significantly lower in AS than in CA or AA. Although not significant, AS had EBC that was more often MP HR than CA and less often HR than AA; studies with larger patient groups will help confirm these trends. The current analysis revealed different underlying gene expression pathways in AS compared with other ethnic groups, which may result in differential clinical outcomes. As genomic profiling data are not widely available for Asian American EBC patients, further analyses are warranted to elucidate these outcomes and identify appropriate therapeutic strategies. Pathology and Genomic Results(unknowns excluded)Asian (n=103)Caucasian (n=103)African American (n=100)p-valueAS vs. CAp-value AS vs. AAER status (IHC)ER Positive69 (94.5%)89 (98.9%)73 (80.2%)0.1250.010ER Negative4 (5.5%)1 (1.1%)18 (19.8%)PR status (IHC)PR Positive64 (87.7%)81 (90%)63 (69.2%)0.4110.006PR Negative9 (12.3%)9 (10%)28 (30.8%)HER2 (IHC/FISH)HER2 Positive3 (4.2%)3 (3.4%)13 (14.3%)0.1720.017HER2 Negative64 (88.9%)85 (95.5%)77 (84.6%)Equivocal5 (6.9%)1 (1.1%)1 (1.1%)MP/BP resultsLuminal A39 (40.6%)51 (53.7%)28 (30.4%)0.2320.043Luminal B45 (46.9%)38 (40.0%)42 (45.7%)HER2 (MP HR)7 (7.3%)4 (4.2%)5 (5.4%)Basal (MP HR)5 (5.2%)2 (2.1%)17 (18.5%) Citation Format: Margaret Chen, Ava Kwong, Carolyn Hendricks, Nina D'Abreo, Laura Lee, Hatem H. Soliman, Charles Cox, Heather M. Kling, Rajith Bhaskaran, Shiyu Wang, Andrea Menicucci, Sarah Untch, William Audeh, FLEX Investigators Group. Molecular profiles and clinical-pathological features of Asian early-stage breast cancer patients [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS7-69.