Uptake of cis-4-[F-18]fluoro-L-proline in urologic tumors

Tumor uptake of the amino acid cis-4-[F-18]fluoro-L-proline (cis-FPro) was studied with PET in eight patients with urologic tumors. Methods: Three pat ients had primary renal cell carcinomas (RCCs), one had a local recurrence of RCC, one had squamous RCC, one had an adrenal hemangioma, one had inguin al metastases of penile squamous carcinoma, and one had suspected metastati c disease from prostate cancer. PET scans of the trunk were acquired at 1 a nd 3-5 h after intravenous injection of 400 MBq cis-FPro and compared with F-18-FDG PET scans and CT. Results: None of the tumors or metastases showed significant uptake of cis-FPro. FDG uptake was seen in one of the three pr imary RCCs, in the local recurrence of RCC, in the squamous RCC, and in the metastases of penile cancer. Conclusion: Cis-FPro appears not to be a prom ising PET tracer in oncology.