Overall, NRG1 fusion events are rare in ovarian, fallopian tube, and primary peritoneal carcinomas, but they may carry diagnostic significance in the context of borderline/low grade serous tumors, which demonstrated exclusively CLU::NRG1 fusions, and could have important predictive implications for response to ERBB/ERBB2/ERBB3-directed therapies. Here, ERBB2 is linked to peritoneal carcinoma.