Tc-99m diphosphonate as a potential radiotracer to detect sentinel lymph nodes in patients with breast cancer.

Abstract

To evaluate the potential of Tc-99m diphosphonate as a tracer for sentinel lymph node biopsy in breast cancer. Lymphoscintigraphs of 35 patients (50.9 ± 10.2years) with breast cancer were acquired after administering a subareolar intradermal injection of Tc-99m diphosphonate 18h before surgery. Static images were taken within 15min (early phase) and 15h after injection (delayed phase). The lymphoscintigraphic identification rate was defined as the percentage of subjects studied with visible foci at axillae. Sentinel lymph node biopsies were performed using a gamma probe and by blue dye injection. Any node that was radioactive or stained with blue dye was labeled as a sentinel lymph node. Lymph nodes without radioactivity or blue dye staining were defined as non-sentinel lymph nodes. The intraoperative identification rate was defined as the percentage of patients with a radioactive sentinel lymph node. Percentages of lymphoid cells expressing S-100, CD83, and CD1a were compared. The lymphoscintigraphic identification rate was 94.3% (33/35) during the early phase and 96.9% (31/32) during the delayed phase, whereas the intraoperative identification rate was 94.3% (33/35). The mean percentages of lymphoid cells that stained positively for S-100 or CD83 were lower in sentinel lymph nodes than in non-sentinel lymph nodes (1.5% vs. 9.0% for S-100, and 4.5% vs. 9.3% for CD83, respectively, p = 0.0286). The mean percentages of lymphoid cells in sentinel lymph nodes and non- sentinel lymph nodes expressing CD1a were 3.3% and 7.0%, respectively (p = ns). Tc-99m diphosphonate can reliably detect regional lymph nodes in breast cancer.