Prostate CancerLaparoscopic Sentinel Lymph Node Dissection – A Novel Technique for the Staging of Prostate Cancer
Introduction
Prevalence of lymph node metastasis in prostate cancer is associated with poor prognosis. Therefore, an exact staging diagnosis of lymph node status is essential before chosing the optimal therapy for the individual patient. Despite improvement in imaging techniques, pelvic lymph node dissection is still the most precise and reliable evaluation method for lymph node staging. The anatomical boundaries of pelvic lymph node dissection for the staging of prostate cancer are still controversially discussed. Although the obturator region is often considered the primary landing site for metastases, recent data demonstrate a more variable lymphatic drainage of the prostate. Therefore, some authors suggest a more extended dissection field to identify metastases that would be missed by a limited dissection [1], [2]. Recent data demonstrate incidences of 35% [3] and 19% [4] of metastases in areas outside the standard field, including the external iliac and obturator regions. However, an extended dissection has been shown to be associated with an increased risk of complications like lymphocele, deep venous thrombosis, ureteral injury or lower extremity edema [5]. Therefore, the sentinel lymph node (SLN) concept has been applied to lymph node staging in prostate cancer [6]. This concept implies that lymph node metastases are first identified in the SLN and that negative SLN exclude metastatic disease. The suitability of the SLN concept for prostate cancer staging has been shown by various authors [7], [8]. It was the aim of this study to evaluate whether SLN dissection can also be performed by means of the laparoscopic approach.
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Patients and methods
A total of 28 patients with prostate cancer and intermediate or high risk for lymph node metastases considered for external beam radiotherapy underwent laparoscopic pelvic lymphadenectomy at our institution (Table 1). All patients were investigated with abdominal/pelvic CT and bone scans preoperatively. Mean PSA was 42 ± 28 ng/ml (10 to 289 ng/ml) with a mean Gleason Score of 6.3 ± 1.1 (3 to 9). Mean patient age was 65.6 ± 5.1 years There was no evidence of distant metastases as shown by bone scan and
Results
No allergic or septic complications occured after radioisotope injection. Transrectal ultrasound allowed an exact bilateral centrally placed intraprostatic injection of the tracer substance. By means of preoperative lymphoscintigraphy combined with a CT scan, a mean of 2.1 ± 1.1 lymph node stations per patient were identified as SLN. The image fusion system allowed an exact three-dimensional delineation of SLN. 43% of the lymph nodes were found in the obturator fossa, 12% in the presacral area,
Discussion
Despite negative CT scan, 25% of our patients presented with lymph node metastases. These findings confirm that modern imaging techniques have only limited sensitivity for lymph node involvement. Preliminary data indicate that innovative methods like 11C-choline PET [9] or high-resolution magnetic resonance imaging with magnetic nanoparticles [10] might become sensitive tools for an accurate preoperative lymph node staging, however further clinical research is needed. With the introduction of
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Neoplasms of the Prostate
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2015, Revista Espanola de Medicina Nuclear e Imagen MolecularCitation Excerpt :To avoid the shine-through phenomenon, they used a gamma probe with the ability to detect gamma rays from 90 degrees laterally.10 Although a strict learning curve exists, laparoscopic extended pelvic lymphadenectomy for validation of the SLN concept is worth performing because this procedure yields an equivalent number of resected nodes with less morbidity.31 Preoperative anatomical information about the lymphatic drainage and the site of the SLNs remains essential during laparoscopy for both planning of operation and probe detection.
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