Internal mammary lymph node drainage patterns in patients with breast cancer documented by breast lymphoscintigraphy

Background: Metastases to internal mammary lymph nodes (IMN) may occur in p atients with breast cancer and may alter treatment recommendations. The pur pose of this study was to identify the frequency of IMN drainage in patient s undergoing boast lymphoscintigraphy and sentinel lymph node dissection (S LND). Methods: The combined technique of peritumoral injection of radiocolloid an d Lymphazurin blue for SLND was performed on 220 patients. All patients und erwent preoperative lymphoscintigraphy before SLND. Lesion location by quad rant included: 110 upper outer (UOQ), 49 lower outer (LOQ), 30 upper inner (UIQ), 24 lower inner (LIQ), and 7 central. Results: Drainage to any nodal basin was observed in 184 of 230 patients (8 4%). IMN drainage was documented in 37 of 220 (17%) of patients. IMN draina ge without evidence of axillary drainage occurred in 2 of 220 patients(1%). Drainage to the IMN based on quadrant location of the lesion was as follow s: UOQ, 10%; LOQ, 27%; UIQ, 17%; LIQ, 25%: and central, 29%. Conclusions: Internal mammary lymph node drainage shown by breast lymphosci ntigraphy is common. Tumors in all quadrants may drain to IMNs, although dr ainage is significantly more common from quadrants other than the UOQ. Furt her studies are needed to determine whether lymphoscintigraphy drainage pat terns identify patients at the highest risk for IMN metastases who may bene fit from radiotherapy.