HER2 Immunohistochemical Expression and Fluorescent In Situ Hybridization (FISH) Testing in Clear Cell Carcinoma of the Gynecologic Tract.

Overall HER2 immunohistochemical scores were: 0 [n=12 (18.5%)], 1+ [n=9 (13.8%)], 2+ [n=40 (61.5%)], 3+ [n=4 (6.2%)].

HER2 0/1+ and cases with USP were more frequent in biopsies (41.7%) and metastatic tumors (45.5%) compared with resections (30.2%) and primary sites (29.6%).

Among HER2 3+ cases, only 1 patient received anti-HER2 therapy (Herceptin followed by Enhertu) and had a mixed response.

Of the HER2 2+ with positive FISH, 4 received anti-HER2 therapy, and only 1 patient had a good response.