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 mor e precise indications for the technique. Methods: Tc-99m-labeled colloid was injected close to the tumor; lymphoscin tigraphy was then performed to reveal the SN. The next day, during surgery, the SN was removed by using a gamma probe. Complete axillary dissection fo llowed, except in later cases recruited to a randomized trial. The SN was e xamined 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 defi nitive histology, prompting introduction of the exhaustive method. In the r andomized trial, the SN was identified in all cases so far, the false-negat ive rate is approximately 6.5%, and in 15 cases, internal mammary chain nod es were biopsied. Conclusions: SN biopsy can reliably assess axillary status in selected pati ents. The problems are the SN detection rate, false negatives, and the intr aoperative examination, which can miss 30% of SN metastases. Our exhaustive method overcomes the latter problem, but it is time consuming.