Use of fluorodeoxyglucose (FDG) PET/CT for staging pelvic lymph nodes in 100 patients with penile carcinoma
The risk of pelvic lymph node metastases can be predicted after inguinal lymph node dissection based on pathologic features of the inguinal specimen. Conventional imaging modalities like CT and MRI have a high specificity, but insufficient sensitivity of 20-40%. FDG-PET/CT performed excellent in previously published smaller series. In this retrospective cohort we describe the diagnostic accuracy of FDG-PET/CT for the staging of pelvic lymph nodes in patients with proven inguinal metastases.
All FDG-PET/CT scans of penile cancer patients with inguinal metastases were retrospectively analysed. We included all PET/CT scans in the following patients: bilateral metastases and or immobile inguinal metastases (cN2-cN3), positive fine-needle aspiration cytology (FNAC), or positive excision biopsy of an inguinal lymph node. PET/CT reports were checked. The findings of PET/CT were compared to a pelvic lymph node dissection (PLND). If not done, the results were compared to positive imaging or follow up of at least one year. Results were evaluated per side (right and left) and per patient.
Scans of 100 patients were included. For 5 patients no reference was available in both pelvic areas, for 16 patient no reference was available unilaterally. This resulted in inclusion of 95 scans, and 174 pelvic sides for analysis. Reference was PLND in 67 pelvic sides, imaging in 33, and follow-up of at least one year in 74 pelvic sides. The results are shown in Table 1. Calculated sensitivity was 77% (95%CI [61-88], specificity was 88% (95%CI [81-93]). Positive and negative predictive values were 67% (95%CI [56-77]) and 92% (95%CI [87-95]), respectively. In a per-patient analysis, sensitivity was 80% (95%CI [64-87]), specificity was 77% (95%CI [64-87]), and positive and negative predictive values were 71% (95%CI [60-80]) and 85% (95%CI [74-91]) respectively.
FDG-PET/CT showed good test performance for staging pelvic lymph nodes of penile carcinoma patients with inguinal metastasis. It had a much higher sensitivity than is reported of CT and MRI, and a high specificity. PET/CT can be a useful tool in the decision to perform a pelvic node dissection.