ERBB2 and cancer: ERBB2 activating alterations were detected in 6.6% (n = 28,508) of tumors in the overall cohort and were most prevalent in gastroesophageal carcinoma (GEC; 18.1%), bladder (18.0%), salivary gland (14.1%), breast (12.7%), and uterine (12.1%) cancers (Fig. 1A).