Clinical relevance of sentinel lymph nodes outside the axilla in patients with breast cancer

Background: Lymphatic mapping in patients with breast cancer can reveal sentinel lymph nodes that are not located at level I-II of the axilla. Little is known about the clinical relevance of these nodes. Methods: Some 113 consecutive patients with clinical stage T1-3N0M0 breast cancer were studied. Based on preoperative lymphoscintigraphy, sentinel node biopsy was performed guided by a gamma probe and patent blue dye. All sentinel nodes that were visible on lymphoscintigraphy were sought. Pathological examination of the sentinel nodes included step-sections and staining with CAM 5.2. Axillary node dissection was performed regardless of sentinel lymph node status. Results: Twenty-one (19 per cent) of 113 patients had sentinel lymph nodes outside level I-II of the axilla, mostly in the internal mammary chain. Twenty-two of the 30 sentinel nodes at these sites were harvested. Three patients had sentinel nodes only outside the axilla. Four other patients had metastases outside the axilla. This changed postoperative treatment in three patients. No postoperative complication occurred. Conclusion: Sentinel lymph nodes outside level I-II of the axilla were present in 19 per cent of patients with breast cancer in this series. Biopsy of these nodes was technically demanding but was performed without additional morbidity. The clinical impact was limited; treatment changed in only 3 per cent.