Counterpoint: sentinel lymph node biopsy is not indicated for ductal carcinoma in situ.

The purpose of axillary surgery in breast cancer is to provide prognostic information to guide the choice of adjuvant systemic therapy. Axillary surgery for ductal carcinoma in situ (DCIS) was abandoned in the 1980s because of the extremely low risk of lymph node metastases and high survival rates. Most women with metastases probably harbored an unrecognized focus of invasion or had metastases subsequent to an invasive local recurrence. Increased use of the less morbid sentinel node biopsy (SNB) for axillary staging of invasive cancer and the recognition that many patients will harbor micrometastases in nodes only recognized by cytokeratin immunohistochemistry (IHC) led two groups to perform SNB with IHC in women with DCIS. One group included all subtypes of DCIS and found metastases in 13% (half of which were detected only on IHC). The other group studied only patients with "high-risk" DCIS. They found metastases in 12% (7 of 9 by IHC only). These groups recommend SNB for women with DCIS. However, the use of SNB in DCIS should be tempered by the uncertainty of the prognostic significance of IHC-detected metastases, the conflicting results of these 2 studies, and the real potential to cause more harm than good from the morbidity of the procedure, the application of unnecessary axillary dissection, and the use of unwarranted adjuvant systemic chemotherapy. These results should be used to generate hypotheses for clinical trials addressing these problems. However, SNB for DCIS remains investigational and should not be generally applied.