What do you think of doing HER2/neu testing on ductal carcinoma in situ?
A. The purpose of HER2/neu testing is to determine the feasibility of systemic treatment with Herceptin and/or high-dose Adriamycin. That being said, neither of these treatments is currently indicated in intraductal carcinoma. There is therefore no role for routine HER2/neu testing in cases of pure intraductal carcinoma. Ironically, though, it was first described in intraductal carcinoma and is essentially limited to high nuclear grade lesions. The current American Society of Clinical Oncology/CAP guidelines recommend only testing invasive carcinoma and only reading the staining of invasive carcinoma when DCIS is also present (though there is typically strong concordance between the two) (Wolff AC, Hammond ME, Schwartz JN, et al. Arch Pathol Lab Med. 2007;131:18–43).
