ERBB2 and breast cancer: When we categorized breast cancers by HER2 postive or negative tumors regardless of hormonal receptor status, a slightly stronger association was shown for HER2 negative (OR for the highest category of alcohol drinking =2.12, 95 % CI 1.53–2.94) than HER2 positive breast cancer (OR 1.77, 95 % CI 1.08–2.92) (Table 3).