If a PSMA-PET scan finds your prostate cancer is “PSMA-positive,” it means that you have at least one metastatic tumor with high levels of PSMA, making you eligible for a type of treatment called PSMA therapy, or PSMA-targeted radioligand therapy. Terms like SUV, SUVmax, and SUVmin in your report provide more details about the cancer.
What SUV Means
In the report, you may see the term “radiotracer uptake,” referring to areas in the body where the tracer has accumulated because it has attached to the PSMA on cells. These areas will show up as bright spots of varying degrees in the images from the PET scan, and a measurement of this brightness (how much accumulation there is) is called a standard uptake value, or SUV.
“The SUV values are quantitative metrics,” Iravani says, “a kind of number of how much [radiation] occurred in a specific volume.”
Importantly, bright spots or uptake don’t necessarily mean cancer. Various organs in the body, including the small intestines, liver, kidneys, and salivary glands, also express PSMA that the radiotracer can bind to. The liver is typically used as a reference organ as it takes up a highly predictable amount of radiotracer. Areas in the scan that are brighter or have higher SUV values than the liver may indicate metastatic tumors.
SUVmax vs. SUVmean
SUVmax refers to the highest SUV value of all the bright spots within a specific region of interest on your scan, says Daniel Sentana, MD, a medical oncologist with the Dana-Farber Cancer Institute in Boston, noting that the brightest spot with the most radiotracer uptake “tends to suggest that’s a place where there are more cancer cells.” SUVmean, on the other hand, is a measurement of the average amount of tracer uptake across that region, he says.
Providers use both SUVmax and SUVmean to help guide a treatment plan and make an educated guess on how responsive your cancer will be to PSMA therapy. They also consider other factors like tumor volume (how many lesions there are), because SUVmax and SUVmean aren’t absolute markers of how well your cancer is going to respond to PSMA therapy, Dr. Sentana says. “We still cannot make complete recommendations about whether you should or you should not get it just because [your scan] does not have a certain amount of SUVmean or SUVmax.”
If You Have a High SUV Number
A high SUV number means that your tumor cells express a lot PSMA or that you have a lot of cancer cells expressing PSMA, which the scan is built to find.It also means you’re likely eligible for PSMA therapy, which works using a drug called lutetium Lu-177 vipivotide tetraxetan (Pluvicto) that attaches to PSMA and then releases cancer killing radiation directly to tumor cells.
Iravani suggests not focusing too much on SUV numbers because those metrics are more relevant to the experts who interpret the scans. For patients, the location, number, and size of the metastatic lesions are “more important than SUV, per se,” he says.
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