Impact of triple negative phenotype on breast cancer prognosis

Abstract

Triple negative (TN) [estrogen receptor (ER), progesterone receptor (PgR)] (ER-/PgR-/Her2/neu-) breast cancer (BC) is an aggressive disease without tumor-specific treatment options. Our objective is to evaluate the relative contribution of combined Her2/neu (Her2) and hormone receptor (HR) status to BC progression. A prospective primary BC cohort of 1550 patients at our institution, stage I-IV, from 1998 to 2003 were categorized by HR and Her2 status into ER+/PgR+/Her2- (HR+/Her2-) (n = 1134), ER+/PgR+/Her2+ [triple positive (TP)] (n = 138), ER-/PgR-/Her2- (TN) (n = 183), and ER-/PgR-/Her2+ (HR-/Her2+) (n = 95). Clinical variables were chart abstracted and vital and disease status updated annually. Log-rank tests and Cox regression analyses were used to assess associations with survival. Patient age ranged from 21 to 88 years and average length of follow-up was 4.24 years. Overall survival at 5 years was 94% (HR+/Her2-), 91% (TP), and 81% (TN and HR-/Her2+) (log rank test = 22.22, p < 0.001). Disease-specific survival at 5 years was 98% (HR+/Her2-), 93% (TP), 88% (TN), and 86% (HR-/Her2+) (log rank test = 25.85, p < 0.001) and 5-year relapse-free survival was 95% (HR+/Her2-), 89% (TP), 84% (TN), and 76% (HR-/Her2+) (log rank test = 20.29, p < 0.001). In a model adjusted for age, race, TNM stage, and treatment using HR+/Her2- patients as the reference group, recurrence risk was 1.98 for TP (95% CI = 1.02 to 3.84), 2.32 for TN (95% CI = 1.32 to 4.08), and 4.25 for HR-/Her2+ patients (95% CI = 2.33, 7.75). A hierarchy of BC phenotypes defined by HR and Her2 status exists with progressively worse disease outcomes by category.