Identification of Sentinel Lymph Nodes in Breast Cancer by Lymphoscintigraphy and Gamma Probe Guidance: Dependence on Route of Injection and Tumour Location

Summary: Background: Sentinel lymph node detection with radiocolloids is confronted with the same problem as the blue dye (BL) method: Even now there is no standardized procedure as regards the application method, the amount of radioactivity and injected volume of the radiocolloid (RC). Therefore, our aim was to find out the most reliable application method and to evaluate a possible tumour‐site dependence of detectability. Methods: Until 1 November 2001, 1567 patients with primarily diagnosed breast cancer and SNB were collected in a nationwide multicentric database (MCDBP, Multicentre Database Project) of the Austrian Sentinel Node Biopsy Study Group (ASNSG). 1116 patients (71.2 %) with radiocolloid detection of the sentinel node (SN), either alone or in combination with blue dye, were included in this evaluation. Exclusion criteria were tumour size > 3 cm, multicentric carcinoma, previous chemotherapy or extensive surgical intervention, enlarged axillary lymph nodes, pregnancy, and lactation. The influence of the injection technique (peritumoral [PT], subdermal [SD] application) and tumour location on the lymphatic drainage pathway and the detection rates were evaluated. Results: On lymphoscintigraphy, drainage to axillary lymph nodes could be detected in 86 % (468/544) using PT, and in 80.1 % (273/341) using SD. Lymphatic drainage to parasternal SNs could be primarily observed using PT in 3.7 % (20/544). Intraoperatively, slightly higher detection rates could be observed only in tumours located in the inner‐upper quadrants using PT (73/83; 88 %) as compared with SD (98/124; 79 %). Intraoperative detection rates for medially and laterally located tumours were comparable for PT (89.5 % vs. 90.5 %), but demonstrated inferior results for medially (68.4 %) vs. laterally (80.7 %) located tumours for SD. Conclusions: In conclusion, as regards axillary SNs, the detection rates of PT and SD seem to be comparable, whereas parasternal SNs seem to be detected more frequently by PT. A dependence on the primary tumour site could be demonstrated only for the inner quadrants, with detection rates being higher with PT than with SD. As a consequence, PT demonstrates advantages in terms of complete lymphatic mapping, independent of tumour location, and would be the method of choice for sentinel node biopsy.