Clinically node-negative breast cancer, internal mammary lymph nodes, and sentinel lymph node biopsy.

We report 2 cases demonstrating that localization of internal mammary (IM) sentinel lymph nodes with lymphoscintigraphy using peritumoral injection of Tc-99m antimony sulfide colloid, followed by resection using minimal access surgery, can reveal nodal metastatic disease in patients with clinically node-negative breast cancer when axillary sentinel nodes are not affected by metastatic disease. When this is found, it changes staging and can affect prognosis and treatment. These cases confirm that the technique used is sampling true sentinel IM nodes, that is nodes that receive direct lymph flow from the breast cancer, and confirm the importance of sampling IM sentinel lymph nodes. Unless techniques are used that are specifically designed to identify IM node drainage from the breast cancer site itself, with subsequent directed surgical removal of sentinel IM nodes, some patients with breast cancer will not be staged correctly.