ERBB2 and amenorrhea: However, as compared to the trastuzumab alone arm, no increased rates of treatment-induced amenorrhea was observed in the dual anti-HER2 blockade arm (odds ratio, 1.19; 95% confidence intervals [CI], 0.94-1.51; p = 0.14) suggesting the possible gonadal safety of these agents, which is in line with previously small studies [5,6].