Functional imaging in penile cancer: PET/computed tomography, MRI, and sentinel lymph node biopsy

The presence and extent of lymph node metastasis and primary tumor are among the most important prognostic factors in penile cancer. While inguinal lymphadenectomy is currently the most accurate means of staging, it is associated with severe morbidity and even mortality. Recent literature was reviewed for alternative means of staging.

Functional imaging modalities distinguish between inguinal lymph nodes with and without metastasis. The false-negative rate of dynamic sentinel lymph node biopsy has recently improved from approximately 20 to 5% in one study. In 13 patients with penile cancer, (18)F-fluorodeoxyglucose-PET/computed tomography was 80% sensitive and 100% specific for lymph node metastasis, but missed micro-metastasis. In seven patients with penile cancer, MRI with lymphotrophic nanoparticles was 100% sensitive and 97% specific for lymph node metastasis.

Combined PET/computed tomography and sentinel lymph node biopsy may help to detect both inguinal micrometastasis and pelvic and abdominal metastasis. Since MRI is highly accurate for staging of both primary penile cancer and its lymph node metastasis, however, it may turn out to be a powerful tool for a one-stop modality in the staging of penile cancer.