Intradermal radioisotope injection optimises sentinel lymph node identification in breast cancer

Aim: Currently there is no consensus on the optimal technique for sentinel lymph node (SLN) identification in patients with breast cancer. The aim was to compare the efficacy of intraparenchymal and intradermal isotope injection in sentinel lymph node mapping for breast cancer. Methods: One hundred and twenty-five patients with histologically confirmed invasive breast cancer underwent SLN mapping using radioisotope and isosulphan blue dye followed by a back-up axillary dissection. The first 80 patients had intraparenchymal (IP) injection of radioisotope given in four portions around the tumor. The remaining 45 patients had an intradermal (ID) injection given at a single site over the tumour. Both groups had isosulphan blue dye injected around the tumour. Sentinel node(s) were identified using a combination of lymphoscintigraphy, blue dye and an intra-operative hand held gamma probe. Results: The preoperative lymphoscintigram (LSG) demonstrated a SLN significantly more often in the ID isotope group compared to the IP isotope group (P=0.002). A combination of blue dye and isotope successfully located the SLN in 96% of the intraparenchymal group and 100% of the intradermal group. Conclusion: Our results suggest that intradermal isotope injection in combination with intraparenchymal blue dye optimises the localization of the sentinel lymph node in breast cancer.