ERBB2-low BC may not be a distinct biologic subtype

Key clinical point: Human epidermal growth factor receptor 2 (ERBB2)-low breast cancer (BC) cannot be considered a distinct biologic subtype of BC because most of its clinicopathologic and prognostic differences are associated with hormone receptor (HR) expression.

Major finding: HR expression was a significant factor associated with the ERBB2 status (adjusted odds ratio for HR-positive vs HR-negative tumors 2.1; P < .001). The pathologic complete response rate was similar in ERBB2-low and ERBB2-0 tumors among patients with HR-positive (P  =  .08) or triple-negative (P  =  .40) BC.

Study details: Findings are from a large cohort study including 5235 patients with ERBB2-negative invasive, stage I-III BC, of which 55.7% and 44.3% of patients had ERBB2-low and ERBB2-0 tumors, respectively.

Disclosures: Dr. Tarantino was supported by an American-Italian Cancer Foundation postdoctoral research fellowship. The authors declared serving on advisory boards of or receiving personal fees, research grants, consulting fees, or honoraria from several sources.

Source: Tarantino P et al. Prognostic and biologic significance of ERBB2-low expression in early-stage breast cancer. JAMA Oncol. 2022 (Jun 23). Doi: 10.1001/jamaoncol.2022.2286