Alternative sites of injection for sentinel lymph node biopsy in breast cancer

Background: Sentinel node biopsy is rapidly gaining popularity as a less invasive approach to nodal staging in breast cancer. The optimal route of injection of radiocolloids and dye is controversial. The purpose of the present paper was to review and assess the literature. Methods: A MEDLINE search for reports of studies involving different injection sites of colloid and/or dye was performed. Results: Although controversial, current evidence suggests that subareolar (SA) or intradermal/subdermal (ID/SD) injection will map the same axillary sentinel nodes (SN) as peritumoral (PT) injection in the vast majority of cases, is at least as successful, and is better logistically. Peritumoral, but not alternative routes, identify extra-axillary sentinel nodes, which are important in a minority of patients. Conclusions: It is recommended that at least some of the radiocolloid be injected peritumorally to avoid missing those SN not located in the ipsilateral axilla. Injection of the dye and a portion of radiocolloid in an ID/SA location is reasonable to take advantage of the general ease and accuracy of ID/SA injections in identifying axillary SN.