F-18 FDG PET/CT and SLN scintigraphy in primary penile cancer - a comparison with histopathology

1459 Objectives Evaluation of the use of F-18 FDG PET/CT and SLN scintigraphy (SPECT/CT) in patients with penile cancer after local surgery for detection of lymph node metastases before sentinel lymph node biopsy/ inguinal staging lymphadenectomy with histopathology serving as gold standard. Methods 15 patients with penile cancer (mean age of 63 years, range 40-77) after local penile surgery underwent F-18 FDG PET/CT and SLN scintigraphy (dynamic data acquisition and static imaging for 2 hours including SPECT/CT) before sentinel node biopsy within 24 hours followed by complete bilateral inguinal lymphadenectomy of the groin within 29 days after PET/CT. SUVmax and SUVmean were determined using VOIs with a 60% threshold. Results Sentinel lymph nodes were detected in all patients (in 3 pts. only in one groin, in 12 pts. bilaterally). In 2/15 pts. inguinal sentinel lymph nodes proved to be metastatic in histopathology. In a patient-based analysis 4/6 (66%) of PET positive patients had histologically proven lymph node metastases. In 2/6 pts. PET was false positive due to histiocytosis. In 9/15 pts. PET was negative (true negative in 8/9 pts., false negative in 1/9 pts. (with a lymphonodular micrometastasis of 4mm)). In the field-based analysis for each groin, lymph node metastases were detected in 4/10 PET positive groins (40%). In 6/10 groins PET was false positive. In 20/30 groins PET was negative (true negative in 19/20, false negative in 1/20). The patient- as well as field-based PET analysis showed a sensitivity of 80% with a specificity of 80% and 75%, respectively, for the detection of lymph node metastases. Conclusions SLN scintigraphy identified sentinel lymph nodes in 15 pts. with penile cancer. In two patients SLN proved to be metastatic in histopathology. F-18 FDG PET/CT detected lymph node metastases in patients with penile cancer after local surgery before sentinel biopsy/inguinal staging lymphadenectomy with high sensitivity and specificity.