Prognostic Utility of Breast Cancer Index to Stratify Distant Recurrence Risk in Invasive Lobular Carcinoma

• Published in: Clinical cancer research 2021-10, Vol.27 (20), p.5688-5696
• Main Authors: Nunes, Raquel, Sella, Tal, Treuner, Kai, Atkinson, Jennifer M, Wong, Jenna, Zhang, Yi, Exman, Pedro, Dabbs, David, Richardson, Andrea L, Schnabel, Catherine A, Sgroi, Dennis C, Oesterreich, Steffi, Cimino-Mathews, Ashley, Metzger, Otto
• Format: Article
• Language: English
• Subjects: Breast Neoplasms - epidemiology; Breast Neoplasms - pathology; Carcinoma, Lobular - epidemiology; Carcinoma, Lobular - pathology; Cohort Studies; Female; Humans; Middle Aged; Neoplasm Invasiveness; Neoplasm Recurrence, Local - epidemiology; Neoplasm Recurrence, Local - pathology; Prognosis; Retrospective Studies; Risk Assessment; Translational Cancer Mechanisms and Therapy
• ISSN: 1078-0432; 1557-3265; 1557-3265
• DOI: 10.1158/1078-0432.CCR-21-0733

The prognostic utility of Breast Cancer Index (BCI) for risk assessment of overall (0-10 years), early (0-5 years), and late (5-10 years) distant recurrence (DR) in hormone receptor-positive (HR+) invasive lobular carcinoma (ILC) was evaluated. BCI gene expression analysis was performed blinded to clinical outcome utilizing tumor specimens from patients with HR+ ILC from a multi-institutional cohort. The primary endpoint was time to DR. Kaplan-Meier analyses of overall, early, and late DR risk were performed, and statistical significance was evaluated by log-rank test and Cox proportional hazards regression. The prognostic contribution of BCI in addition to clinicopathologic factors was evaluated by likelihood ratio analysis. Analysis of 307 patients (99% ER+, 53% T1, 42% N+, 70% grade II) showed significant differences in DR over 10 years based on BCI risk categories. BCI low- and intermediate-risk patients demonstrated similar DR rates of 7.6% and 8.0%, respectively, compared with 27.0% for BCI high-risk patients. BCI was a significant independent prognostic factor for overall 10-year DR [HR = 4.09; 95% confidence interval (CI), 2.00-8.34; = 0.0001] as well as for both early (HR = 8.19; 95% CI, 1.85-36.30; = 0.0042) and late (HR = 3.04; 95% CI, 1.32-7.00; = 0.0224) DR. In multivariate analysis, BCI remained the only statistically significant prognostic factor for DR (HR = 3.49; 95% CI, 1.28-9.54; = 0.0150). BCI is an independent prognostic factor for ILC and significantly stratified patients for cumulative risk of 10-year, early, and late DR. BCI added prognostic value beyond clinicopathologic characteristics in this distinct subtype of breast cancer.