Purpose: We investigated the feasibility and validity of the sentinel lymph node concept for patients with prostate cancer.
Materials and methods: A total of 24 patients (mean age 68.1 years) with prostate cancer but without detectable distant metastases were enrolled in this study. Radioactive tracer (technetium labeled phytate) was injected into the prostate 5 to 6 hours before surgery. Preoperative lymphoscintigraphy was viewed, and in vivo and ex vivo gamma probing was performed during the surgery, which included backup extended lymph node dissection. Radioactivity of the excised lymph nodes was measured and validated with an autowell scintillation counter.
Results: Radioactive positive (hot) nodes were identified in 17 of the 24 (70.8%) patients by lymphoscintigraphy, in 21 of 24 (87.5%) patients by in vivo probing and in 23 of 24 (95.8%) patients by ex vivo probing. On an individual basis the numbers of hot nodes identified by lymphoscintigraphy and in vivo probing were low (40% and 36%, respectively) compared to the high detection rate for ex vivo probing (91%).
Conclusions: Although sentinel lymph nodes can be used for prostate cancer, detailed lymph node mapping and extended dissection backup are currently needed. It is also important to establish novel procedures for accurate and complete removal of all hot nodes.