The prognostic value of HER2 status and efficacy of anti-HER2 therapy in patients with HR-positive mucinous breast cancer: a nationwide study from the Korean Breast Cancer Society

Purpose The effect of human epidermal growth factor receptor 2 (HER2) status on mucinous carcinoma (MC) of the breast is unknown due to the rarity of HER2-positive cases. We evaluated the prognostic value of HER2 status and the efficacy of anti-HER2 therapy in patients with hormone receptor (HR)-positive MC.