ERBB2 and squamous cell carcinoma: This finding differs from the results of a Mexico City study, which found positive HER2 staining only in a single patient (1 [3%] of 35) with squamous cell carcinoma of the uterine cervix (22); the inconsistent results may be related to different disease stages, HER2 assays, lack of adenocarcinoma or adenosquamous cell types, or all of these factors.