The PET scan for prostate cancer can sometimes be use to determine if prostate cancer has spread to other sites in the body and, if so, where. The PET scan is often misunderstood by both patients and some doctors. Read on to learn all about the PET scan for prostate cancer and why it is often misunderstood.
What Is a PET Scan?
The acronym "PET" stands for positron emission tomography. For our purposes, it doesn't really matter what that means beyond the fact that tiny amounts of radioactivity (which is injected into the body) is detected outside of the body by a large machine commonly known as the "PET scanner".
A PET scan involves the injection of a form of radioactively tagged glucose (a sugar that the body naturally metabolizes or uses). Tissues in the body that use up a lot of glucose will also use up a lot of the special radioactively tagged glucose used for the PET. Those tissues will then be marked with radioactivity that can be detected by the PET scanner.
Lots of normal tissues rapidly use glucose (such as the heart, liver, spleen, and kidneys). What makes the PET scan useful, however, is that cancer cells typically also use a lot of glucose because they are dividing and multiplying at a much higher rate than normal cells.
By detecting abnormal sites of high glucose use on the PET, doctors can determine where there may be additional areas of cancer scattered throughout the body. This can help in choosing the most appropriate treatment.
Additionally, at many hospitals, PET is now combined with a CT scan to make a precise determination of exactly where cancer has spread much easier.
Why Isn't PET Used Very Much for Prostate Cancer Detection?
PET is not used very much for detecting prostate cancer spread. For some reason, prostate cancer cells do not seem to rapidly use the radioactively labeled glucose injected for a PET exam. This means that, even if there is prostate cancer that has spread to another area of the body, the PET scan could very well miss it.
By far, the most used (and useful) test for detecting prostate cancer metastases is the bone scan.
Currently, researchers are working to develop new radioactive compounds for PET that may be able to more accurately detect prostate cancer metastases.
Brant and Helms. Fundamentals of Diagnostic Radiology. 2006.