Addition of trastuzumab improves overall survival in advanced uterine serous carcinoma (USC). Left: Among all patients, OS was 24.4 (CP) versus 29.6 (CP+T) months (HR 0.581, 90% CI 0.339–0.994, p=0.0462). Right-top: Benefit was greatest in those undergoing primary therapy with advanced disease (OS 25.4 months versus not reached, HR 0.492, 90% CI 0.249 – 0.974, p=0.0406). Right-bottom: Benefit was not apparent in the recurrent setting (22.5 versus 25.0 months, HR 0.864, 90% CI 0.355–2.100, p=0.3929).