Original article Use of the gamma probe in sentinel lymph node biopsy in patients with prostate cancer Neivo Silva Jr a , Carlos E. Anselmi a , Osvaldo E. Anselmi a , Rafael R. Madke a , Angela Hunsche a , Jose S. Souto b , Carlos A.V. Souto b , Dante Sica F. b , Giovani T. Pioner b , Edson C. Macalos c , Antonio A. Hartmann d and Mauricio S. Lima e Objective To describe the reproducibility of the sentinel lymph node technique in patients with prostate cancer and verify if there is improved accuracy over modified lympha- denectomy. Material and methods Twenty-three patients with biopsy proven prostate cancer were enrolled in this study. Lymphoscintigraphy was performed after the transrectal administration of 99m Tc sulfur colloid guided by ultrasound, with one injection in each prostate lobe. Images were obtained 15 and 180 min after injection. Sentinel lymph node was harvested during surgery using a gamma probe, followed by extended lymphadenectomy. Results The mean age of the patients in this study was 66 years. An average of 3.36 sentinel lymph nodes was found for each patient. Radioactive lymph nodes were identified by the gamma probe in 21 out of 23 patients. In one of the patients there was no radiopharmaceutical migration from the injection site and in another the sentinel lymph node was visualized by lymphoscintigraphy but was not found during surgery. Three patients had lymph node metastasis; in one of these patients the sentinel lymph node was the only positive node and was found outside the modified lymphadenectomy region (obturator fossa and the external iliac). Conclusion Sentinel lymph node biopsy in prostate cancer adds important information to the staging of patients, not always attained through the lymphadenectomy restricted to the obturator fossa and external iliac. Such information is essential for the choice of the best treatment to be applied. Nucl Med Commun 26:1081–1086 c 2005 Lip- pincott Williams & Wilkins. Nuclear Medicine Communications 2005, 26:1081–1086 Keywords: sentinel lymph node, lymphoscintigraphy, prostate cancer, gamma probe a Nuclear Medicine Laboratory, and Departments of, b Urology, c Radiology, d Pathology, Complexo Hospitalar Santa Casa de Porto Alegre, Brazil and e Catholic University in Pelotas, Brazil. Correspondence to Dr Neivo S. Junior, Nuclear Medicine Laboratory, Complexo Hospitalar Santa Casa, R. Sarmento Leite, 187, Centro, Porto Alegre, RS, Brazil, ZIP 90050-170. Tel: + 55 51 32148338; fax: + 55 51 32148177; e-mail: neivojr@terra.com.br Received 30 May 2005 Accepted 13 August 2005 Introduction Prostate cancer is recognized as one of the leading medical problems faced by men. In Europe, an estimated 2.6 million new cases of cancer are diagnosed each year. Prostate cancer constitutes about 11% of all male cancers in Europe [1], and accounts for 9% of all cancer deaths among men within the European Union. The American Cancer Society estimates that in 2005 about 232 090 new cases of prostate cancer will be diagnosed (http:// www.cancer.org). In Brazil, prostate cancer is the second most frequent cancer in men, with an estimated 46 330 new cases in 2005 (http://www.inca.gov.br). The stage of the disease is the most important factor in the choice of treatment options and in the prediction of a patient’s survival. The prognosis depends on nodal cancer volume [2], extracapsular extension [3] and the number of affected lymph nodes [4]. The presence of pelvic lymph node metastases indicates a poor prognosis for patients with clinically localized prostate cancer. Radical prostatectomy, the best chance of cure, is not undertaken when there is evidence of nodal involvement or distant spread. Thus definition of the status of pelvic lymph nodes draining the prostate is critical to staging and management. Computerized tomography [5], magnetic resonance [6] and positron emission tomography using 2-[ 18 F]-fluoro-2-deoxy-D-glucose ( 18 F-FDG) [7] have limited value owing to their low sensitivity for detecting nodal involvement. Preoperative 11 C-choline positron emission tomography (PET) has been shown to provide good sensitivity and accuracy in pelvic lymph node staging, though its use should be restricted to facilities with cyclotrons nearby. Lymphadenectomy is the most accurate technique for detecting nodal metastasis, but its accuracy is dependent on the extent of the area and the number of lymph nodes disected [8,9]. In an attempt to overcome this limitation 0143-3636 c 2005 Lippincott Williams & Wilkins Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.