While multiparametric MRI and color Doppler ultrasound are excellent tools for monitoring disease inside the prostate, scanning the rest of the body for cancer that may have spread to the lymph nodes or bones is also critical. Body scans are necessary for every Stage of Blue except Sky. Traditionally, doctors have relied on CT scans and bone scans. However, their accuracy is disappointing. Undetected spread is the most common reason for cancer recurrence after the initial treatment.
Positron emission tomography (PET) scans provide three-dimensional images of the whole body. The most recent and exciting discovery is that prostate cancer relies on fat as its energy source. Prostate tumors rapidly absorb fat when it is injected into the bloodstream, and if the fat is made radioactive by the insertion of radioactive carbon (C11), the tumors “light up” on a scanner. Lymph node metastases as small as 5-6 mm can be detected.
After lymph nodes, bone is the second most common site of metastatic spread. Standard bone scans use a radiotracer called Technetium-99, which is unfortunately not very specific. Other changes in the bone, such as arthritis or benign lesions, can be mistaken for cancer metastasis. A PET scan called NaF18 (radioactive sodium fluoride) provides superior specificity and sensitivity when compared with Technetium-99. NaF18 PET imaging used in combination with C11 acetate PET imaging in the same patient offers the most comprehensive method currently available for detecting cancer metastases.
Axumin, Galium-68 PSMA, C11 acetate and Choline PET scanning for prostate cancer are a giant leap forward over older scanning techniques. Preliminary studies with Galium-68 PSMA provide excellent images, though this technology is still investigational. Axumin detects increased amino acid metabolism in the cancer cells similar to how C11 exploits increased lipid metabolism. Axumin is now FDA approved and has recently become commercially available.
Fabio Almeida, MD graduated top of his class and with honors from The Chicago Medical School. He completed a residency and fellowship in nuclear medicine at the University of San Francisco, and is certified by the American Board of Nuclear Medicine and the Certification Board of Nuclear Cardiology. He was in academic practice at the University of California, San Francisco, and private practice until 2005. Dr. Almeida is one of the pioneers in the development and implementation of cross modality fusion for cancer imaging (SPECT, PET, CT and MRI) and PET/CT. He also worked for the Centers for Disease Control after 9/11 for several years as a physician and informatics specialist consultant.