Key clinical point: Survival outcomes in human epidermal growth factor receptor 2-positive (HER2+) invasive lobular carcinoma (ILC), a rare and poorly characterized subtype of breast cancer (BC), were similar to those in HER2+ invasive ductal carcinoma (IDC) or HER2-negative (HER2−) ILC and did not improve with anti-HER2 treatment.
Major finding: Compared with patients with HER2+ ILC, patients with HER2+ IDC and HER2− ILC had similar overall survival (OS; P = .6 and P = .29, respectively) and disease-free survival (DFS; P = .69 and P = .18, respectively) outcomes. Anti-HER2 therapy did not improve OS or DFS in patients with HER2+/HER2−ILC (both P = .2), although it improved survival outcomes in patients with HER2+ IDC ( P < .001).
Study details: Findings are from a population-based study including 833 patients with HER2+ IDC, 62 patients with HER2+ ILC, and 685 patients with HER2− ILC.
Disclosures: This study did not receive any funding. The authors declared no conflicts of interest.
Source: Kada Mohammed S et al. HER2-positive invasive lobular carcinoma: A rare breast cancer which may not necessarily require anti-HER2 therapy. A population-based study. Breast Cancer. 2023 (Jan 30). Doi: 10.1007/s12282-022-01432-3