PSA (prosthetic specific antigen) is a normally occurring molecule in the prostate. When cancer develops in the prostate, the PSA is commonly elevated. Because of this, it is often routinely checked on an annual or biannual basis. All too frequently, mainly because prostate cancer is the most common cancer in men, it is found elevated. What happens after that is open to discussion, but new technologies are now available to help in the decision process.

Historically, an elevated PSA led to needle biopsies of the prostate. Because it was unknown where the focus of cancer may be in the prostate, multiple stabs (as many as 40) with the biopsy needle were necessary to find and capture the malignant cells. Side effects would include bleeding in the urine, sepsis and occasionally death from septic shock. Over the past 10+ years, MRI has been able to usually define the abnormal area within the prostate, which would allow for a much less brutal targeted biopsy. However, the MRI scan may not be positive or negative, but iffy at best.

In the 2020s, a discovery known as the PSMA has led to a more accurate and definitive diagnosis of the abnormal area within the prostate. PSMA is a protein found on the outer membrane of prostate cancer cells. The more malignant the cancer, the more PSMA is produced.

Scientists have produced an antibody against the PSMA molecule and have attached a radionuclide tracer to it. This unique combination, after an injection into a vein, will attach itself specifically to a malignant prostate cancer cell. The radionucleotide tracer will emit a low-grade radiation signal which can be detected by the PET scan. This PSMA-PET scan can show the presence of prostate cancer, even if the MRI is equivocal or even negative. Furthermore, this can show the presence or absence of any spread of the prostate cancer elsewhere in the body. Today, the PSMA-PET can be used as the first diagnostic step, sometimes eliminating the need for MRI, and guiding a precise, much less invasive biopsy

One could say the PSMA-PET is a threefer, that is to say,  3 for 1, showing cancer, location, and spread all in one test.

Dr. Charlie Barnett is a contributor to KnoxTNToday, where he writes a weekly column, DocTalk, sharing his expertise on health and wellness management.

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