Restaging of penile cancer patients with 18F-FDG PET/CT

Objectives This study is to evaluate whether FDG PET/CT is useful in the follow-up of penile cancer patients after initial treatment.

Methods 17 consecutive patients with squamous cell carcinoma of the penis who underwent FDG PET/CT between 01/2007 and 11/2010 were identified in our database. Of these, 12 patients had restaging 18F-FDG PET/CT after initial treatment and had accessible follow-up information were included in the study. All scans were done on a 64-slice GE PET/CT (DVCT) after injection of approximately 15 mCi of 18F-FDG. Whole body noncontrast CT was performed as part of the PET/CT procedure. Any radiotracer uptake with a corresponding lymph node on PET/CT scan was interpreted as positive for metastasis.

Results Of the 6/12 patients with positive FDG uptake in inguinal nodes, 5 patients had surgically proven metastatic disease. Total of 7 metastatic lymph nodes were resected, of which 6 were positive on FDG PET/CT (mean size 2.5± 1.3cm with an average SUVmax of 6.5 ± 3.2). One patient with 3 PET/CT positive lymph nodes (average size 1.9±0.1cm, SUVmax 2.0± 0.3) was disease free based on repeated imaging studies and clinically follow-up of 23 months. All 6/12 patients with negative FDG PET/CT for locoregional metastasis had no active disease at average clinical follow-up of 19.4 months (SD±10). The sensitivity of detecting inguinal nodal metastasis on a per-patient basis was 100%, and the specificity was 85.7%. On a nodal basis, the sensitivity for detection of lymph node metastasis was 85.7 % (6/7). Two patients had positive uptake in the penile remnant, of which one was confirmed as false positive for penile recurrence.

Conclusions 18F-FDG PET/CT is very accurate in detecting locoregional metastasis on follow-up penile cancer patients