Human epidermal growth factor receptor 2 overexpression in breast cancer of patients with anti-Yoassociated paraneoplastic cerebellar degeneration

Abstract

Isolated case reports suggest that breast tumors from patients with paraneoplastic cerebellar degeneration (PCD) and Yo antibodies overexpress human epidermal growth factor receptor 2 (HER2). HER2 overexpression is present in 1525 of breast cancers and is associated with poor prognosis. We retrospectively analyzed the status of HER2 in breast tumors of 27 patients with anti-Yoassociated PCD to evaluate whether HER2 overexpression in this group of patients is higher than expected. In addition, we analyzed HER2 status of 19 breast tumors from patients with paraneoplastic neurological syndromes and Ri antibodies to see whether HER2 was specifically related to anti-Yoassociated PCD. We also assessed cdr2 expression (the onconeural antigen recognized by Yo antibodies) in 21 HER2-positive breast tumors from patients without paraneoplastic neurological syndromes. HER2 was overexpressed in 26 patients (96.3) with anti-Yoassociated PCD but only in 2 patients (10.5) with paraneoplastic neurological syndromes associated with Ri antibodies (P