PET in testicular cancer.

Testicular cancer is a rare tumor, subdivided into seminomatous and nonseminomatous tumors. Whereas there are no serum tumor markers in the first group, they are present in nonseminomatous tumors, and are also important prognostic factors. Overall, the prognosis for testicular cancers is good, which makes the choice of accurate treatment intensity between under- and overtreatment often difficult. Residual masses in advanced clinical stages occur frequently but are nonvital tissue. PET with F-18 FDG has no defined role in imaging of primary tumors where CT is the first-choice imaging modality. For assessing the success of chemotherapy in the presence of residual masses, especially in pure seminoma, F-18 FDG PET is an important tool. In nonseminomatous tumors, it is hampered by the false-negative results in mature teratoma, for which reason false-negative results are a common problem. F-18 FDG PET performs best in predicting relapse in seminoma residuals larger than 3 cm. So far, no alternative to F-18 FDG for PET imaging of testicular cancer has been found. PET-CT has not yet been proven to be superior to PET alone in testicular cancer.