Lymphatic drainage from the treated versus untreated prostate: feasibility of sentinel node biopsy in recurrent cancer

The goal of this study was to establish the feasibility of sentinel node biopsy in patients with recurrent prostate cancer after initial local treatment and to compare lymphatic drainage patterns of the treated versus untreated prostate. In ten patients with a proven local recurrence after initial local treatment (four external beam radiation, four brachytherapy and two high-intensity focused ultrasound), the radiotracer (99mTc-nanocolloid, GE Healthcare) was injected into the prostate. Planar images after 15 min and 2 h were followed by SPECT/CT (Symbia T, Siemens) to visualize lymphatic drainage. Laparoscopic sentinel lymphadenectomy was assisted by a gamma probe (Europrobe, EuroMedical Instruments) and a portable gamma camera (Sentinella, S102, Oncovision). Sentinel node identification and lymphatic drainage patterns were compared to a consecutive series of 70 untreated prostate carcinoma patients from our institute. Lymphatic drainage was visualized in all treated patients, with a median of 3.5 sentinel nodes per patient. Most sentinel nodes were localized in the pelvic area, although the percentage of patients with a sentinel node outside the pelvic para-iliac region (para-aortic, presacral, inguinal or near the ventral abdominal wall) was high compared to the untreated patients (80 versus 34%, p = 0.01). In patients with recurrent prostate cancer, 95% of the sentinel nodes could be harvested and half of the patients had at least one positive sentinel node on pathological examination. Lymphatic mapping of the treated prostate appears feasible, although sentinel nodes are more frequently found in an aberrant location. Larger trials are needed to assess the sensitivity and therapeutic value of lymphatic mapping in recurrent prostate cancer. (orig.)