Lymphoscintigraphy and radioguided biopsy of the sentinel axillary node inbreast cancer

Lymphoscintigraphy associated with radioguided biopsy of the sentinel node (SN) is well established in clinical practice for melanoma. In breast cance r, the SN concept is similarly valid, and lymphoscintigraphy is a useful me thod for localizing the axillary SN. The aim of this study was to optimize the lymphoscintigraphy technique in association with a gamma ray detecting probe (GDP) for identifying and removing the SN in breast cancer patients. Methods: Two-hundred fifty patients with operable breast tumor underwent ly mphoscintigraphy before surgery. Three different size ranges of Tc-99m-labe led colloid particles (<50, <80 and 200-1000 nm) were used, with either sub dermal (above tumor) or peritumoral injection. Early and late scintigraphic images were obtained in anterior and oblique projections, and the skin pro jection of the detected SN was marked. Sentinel nodes were identified and r emoved with the aid of the GDP during breast surgery; they were tagged sepa rately. Complete axillary dissection followed. In 40 patients, a blue dye w as also administered in addition to subdermal radiolabeled colloid to compa re blue dye mapping with lymphoscintigraphy localization. Results: Lymphosc intigraphy successfully revealed lymphatic drainage in 245 of 250 patients (98%). The axillary SN was identified in 240 patients (96%). SN biopsy corr ectly predicted axillary node status in 234 of 240 patients (97.5%). Lympho scintigraphy and GDP detected the SN most easily and consistently when 200- 1000 nm colloid was administered subdermally in an injection volume of 0.4 mi. Blue dye mapping was successful in 30 of 40 patients (75%). In 26 of th ese patients, the dye and lymphoscintigraphy identified the same node; in 4 cases different nodes were identified. None of these four patients had axi llary disease. Conclusion: Lymphoscintigraphy is a simple procedure that is well tolerated by patients. Sentinel node identification is more reliable when large-size radiolabeled colloids are injected in a relatively small in jection volume (0.4 mi). Use of a GDP greatly facilitates precise pinpointi ng and rapid removal of the SN.