Comparison of different injection sites of radionuclide for sentinel lymph node detection in breast cancer - Single institution experience

Background: There are still ongoing controversies about several aspects of lymphatic mapping and sentinel lymph node biopsy for breast cancer, including injection site of radioisotope and blue dye. This study aims to evaluate the success rate of different radiocolloid injection techniques in the detection of sentinel lymph nodes (SLN) in early breast cancer. Study Design: One hundred ninety-two women with early breast cancer were included. For SLN mapping with lymphoscintigraphy (LSG), 5 different injections were used. Group A (36 patients) had 4 peritumoral (PT), group B (n = 36) had 1 subdermal (SD) injection of Tc-99m rhenium sulfide colloid over the tumor quadrant. Group C (59 patients) had I PT and I SD combined injections. In group D (56 patients), lymphatic mapping was performed with 2 intradermal periareolar (ID-PA) injections. In group E (n = 41), 2 ID-PA and I PT combined injections were performed. Early dynamic and delayed images were obtained. A surgical gamma probe was used to explore the SLNs. Surgical specimens were evaluated histopathologically. The SLN identification rate, false negative rate, and comparison of groups were evaluated by statistical methods. Results: The SLN identification rate by LSG in groups A, B, C, D, and E were 72%; 92%, 93.2%, 98%, and 95%, respectively. The highest detection rates for the axilla (98%) and mammary internal (MI) drainage (22%) were obtained with ID-PA injections and a peritumoral injection, respectively. Seventy of 192 patients (36.4%) had positive axillary lymph nodes. The only statistically significant difference was between the PT and SD injection groups in axillary SLN identification rate by LSG (P = 0.016). Conclusion: The success rate was superior with intradermal periareolar injection compared with PT and SD injection to visualize the axillary SLN. However, PT deep injection combined with ID-PA injections may be more favorable to demonstrate the primary internal mammary (IM) lymphatic drainage.