Thirty One Cases of Radioguided Biopsies of Sentinel Lymph Nodes Located in the Internal Mammary Chain

Abstract

INTRODUCTION: The methodology of sentinel lymph node (SLN) biopsy in breast cancer has renewed the interest in harvesting lymph nodes in internal mammary chain (IMC). The presence of the disease in IMC nodes implicates in increase of the risk for distant metastases caused by secondary seeding from persistent disease. SLN biopsy in IMC is not a troublesome procedure and could modify the indication of adjuvant chemotherapy or regional radiotherapy. However, the effect of SLN biopsy in IMC on survival still is unknown. This study examines the histopathologic involvement of sentinel nodes identified by lymphatic mapping within this drainage pathway. METHOD: We performed SLN mapping in 831 patients with early infiltrating BC staged as T1-2 N0. On the day before surgery, a solution containing dextran labeled with technetium was injected around the lesion under ultrasound or stereotaxic mammography guidance. Planar scintigraphy images were obtained with a gama camara. Among the cases in whom the SLN was mapped (hot spot) in IMC (3 SLN exclusively in IMC and 28 with simultaneous SLN in axilla), in 31 the SLN was retrieved. The IMC nodes were explored through the same incision made for removal of the primary tumor. After splitting the pectoral muscle fibers, the intercostals muscles were separated from the lower rib to expose the internal mammary vessels in contact with the SLN over the parietal pleura. Never was a rib resected. RESULTS: in 4 patients (4/31 = 12. 9%) metastatic SLNs in IMC were discovered. of them, in one occasion the nodal involvement was seen only in IMC, while in the other 3, the axillary SLNs also contained metastatic disease. Upstaging of the BC was observed in 12. 9% of the patients who were submitted to SLN biopsy in IMC, causing better selection of cases who might benefit from postoperative irradiation of IMC and systemic chemotherapy. In one patient, the internal mammary artery was damaged during the pursuit of the node, but secure hemostasis was obtained without difficulty easily. There was not any case of accidental opening of the pleural cavity. CONCLUSION: SLN biopsy in IMC provide a more accurate staging of BC patients. Prospective randomized trials are needed to determine whether the adjustments in adjuvant therapy, caused by the biopsy, are associated with improvements in disease-free and overall survival.