By the time a man hits his mid-50s, he’s probably begun to learn a thing or two about his prostate. He knows it’s a sex gland located inside his pelvic region, that it’s normally the size of a walnut, that it often begins to grow in size during middle age, and that it is susceptible to cancer and can be the cause of urinary problems. If he goes for an annual physical and discusses his blood work with his doctor, he’s probably become at least passingly familiar with the term “prostate-specific antigen,” or PSA. His doctor has likely explained to him that a high PSA level is not good, since it could be a harbinger of cancer. But there’s a lot more to know about the PSA blood test and what it signifies.
PSA is an enzyme produced in the prostate which has an important role in reproduction…It reduces the viscosity of semen by breaking down proteins that would otherwise give it a gel-like quality. Less-viscous semen allows for easier travel on the part of sperm cells that must make their way into the cervix.
Not all of a man’s PSA remains localized to the reproductive organs. Some of it penetrates the capillary membranes and escapes into the broader circulatory system. A portion of this circulates throughout the bloodstream without binding to other substances. This is known as “free PSA.” The remainder binds to circulating protease inhibitors. The ratio of free to bound PSA is one of the predictors of cancer risk.
PSA testing consists of drawing blood, usually from the arm, and measuring the concentration of PSA contained in it. Abnormally high levels of PSA circulating in the bloodstream are an initial indicator of possible prostate cancer. However, that isn’t because cancerous prostate cells produce more PSA than normal prostate cells. Instead, it’s because the cancerous cells lack a layer that would normally retain their PSA, so it more easily passes out of the cell, into the surrounding fluid, and on into the bloodstream.
PSA test results are expressed in terms of nanograms per milliliter, or ng/mL. The normal ranges for men increase slightly with age, from 0-2.5 ng/mL for men in their 40s to 0-6.5 ng/mL for men older than 70. And yet it’s certainly not the case that having a PSA level higher than these is a definitive marker of cancer, especially since other conditions and factors can create high PSA levels. Most doctors become concerned when they see a PSA higher than 10 ng/mL, and a level higher than 50 is considered very indicative of cancer. But you should always discuss a high PSA result with your doctor, since it needs to be interpreted alongside several other factors before jumping to conclusions.
A PSA test entails minimal risk and is not particularly expensive. Yet using PSA to screen healthy men for prostate cancer is not as widely accepted as you might think…or as it once was.
There’s a certain paradox regarding PSA testing that makes it something of a conundrum as a public-health issue. Most prostate cancers are quite slow-moving, taking years or even decades to become dangerous. Elevated PSA can be an early harbinger of such cancers, which can be safely left untreated as long as they are monitored for changes. Yet that’s not true of all prostate cancers, some of which are aggressive and require immediate treatment…and in those cases, the earlier the intervention, the better. So should doctors screen all men over a certain age and follow up on all elevated PSAs with biopsies or even treatments of relatively innocuous cancers? That strategy unquestionably leads to overtreatment, which is costly, often painful, and disruptive to people’s lives. On the other hand, choosing not to screen everyone increases the risk that the minority of men with aggressive cancers will not be treated as early as they could have been. So, to screen or not to screen? The medical community is still wrestling with this question.
Whether you choose to undergo annual screening (for most men, this starts at around age 45) is a personal matter to be discussed in consultation with a trusted physician. Then, if your test yields an abnormality, it’s time to face another set of decisions. Upon seeing a high PSA, some doctors will be eager to order a biopsy to confirm or rule out a cancer diagnosis and, if cancer is indeed present, to identify its type. But PSA levels can rise for lots of reasons besides cancer, so getting a biopsy could be jumping the gun. There are several intermediate steps to take and considerations to weigh before you take that step….
As stated earlier, a man’s levels of PSA typically increase with age. This is thought to be an evolutionary adaptation to counteract age-related decreases in sperm count and quality, allowing the male to remain fertile into the second half of his lifespan. If a typical man underwent annual PSA testing from the age of 40 to 80, he would almost certainly see a fairly steady increase in levels over that period. Some proponents of annual testing argue that at the individual level, having a baseline PSA reading as well as historical tracking of levels helps to make sense of any sudden new increases.
An elevated PSA score can be caused by a condition called prostatitis, which is an inflamed prostate gland. Another condition, called benign prostatic hyperplasia (also known as enlarged prostate) is also a frequent cause of high PSA. Neither of these conditions is indicative of cancer, however.
It’s important to understand that PSA levels normally fluctuate. Your PSA score can temporarily rise after sexual activity or vigorous exercise. Some procedures involving the prostate cause PSA levels to rise. And certain medications can cause your PSA level to rise or fall.
An above-normal test result should prompt a discussion with your doctor. Does this represent a trend? Have your levels been slowly but steadily increasing with age, or have they suddenly jumped dramatically? Could a medication or recent procedure account for the increase? Is it possible that your prostate is enlarged or inflamed but non-cancerous? Carefully examining these and other factors will help you and your doctor decide on the best steps to take next.
