Radioguided sentinel node biopsy to avoid axillary dissection in breast cancer

Background: Sentinel node (SN) biopsy may predict axillary status in breast cancer. We retrospectively analyzed more than 500 SN cases, to suggest more precise indications for the technique. Methods: Tc-99m-labeled colloid was injected close to the tumor; lymphoscintigraphy was then performed to reveal the SN. The next day, during surgery, the SN was removed by using a gamma probe. Complete axillary dissection followed, except in later cases recruited to a randomized trial. The SN was examined intraoperatively by conventional frozen section, in later cases by sampling the entire node and using immunocytochemistry. Results: In the first series, the SN was identified in 98.7% of cases; in 6.7%, the SN was negative but other axillary nodes were positive; in 32.1%, the SN was negative by intraoperative frozen section but metastatic by definitive histology, prompting introduction of the exhaustive method. In the randomized trial, the SN was identified in all cases so far, the false-negative rate is approximately 6.5%, and in 15 cases, internal mammary chain nodes were biopsied. Conclusions: SN biopsy can reliably assess axillary status in selected patients. The problems are the SN detection rate, false negatives, and the intraoperative examination, which can miss 30% of SN metastases. Our exhaustive method overcomes the latter problem, but it is time consuming.