What is PSA and should I have it tested?

| Posted On Jun 07, 2016 | By:

Prostate cancer is the most common non-skin cancer diagnosed in men in the United States. According to the American Cancer Society, approximately one in six men will be diagnosed with the disease in their lifetime, over 220,000 new cases are diagnosed annually, and it kills more men each year than any malignancy other than lung cancer.  It’s therefore understandable that many men would be interested in screening for prostate cancer.

For many years, the common test used to screen for prostate cancer was a digital rectal exam (DRE), which for many men is as uncomfortable to receive as prostate cancer is to talk about. In the early 1980s, a blood test called prostate specific antigen (PSA) was developed. PSA measures a protein released from prostate tissue (cancerous and non-cancerous), and came into use as a means of monitoring response to prostate cancer treatment and detecting recurrence. Over time, interest grew in using this blood test to screen for disease (prostate cancer) rather than just monitor known disease.

In 1994, the FDA approved the use of the PSA test in conjunction with a DRE to test asymptomatic men for prostate cancer, which helped to significantly increase the number of early diagnoses. There was optimism that its widespread use would save lives.  Taken from a certain perspective, it has: the five-year relative survival in men with prostate cancer is now about 99% – what could possibly be wrong with that?

Consider the following statistics:

What this tells us is that prostate cancer is common, and more importantly, very few men die from it.  You might wonder, “Maybe it’s because they had PSA testing done.”  Well, the reality is that most men, diagnosed or not, won’t die from prostate cancer. Therefore, while PSA has led to a significant increase in the number of diagnoses, we’ve seen a much, much smaller decrease in the number of deaths.

In late 2009 and early 2010, two large, international trials – Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO) and the European Randomized Study of Screening for Prostate Cancer (ERSPC) – were published, leading to a shift in how PSA was viewed for the purpose of prostate cancer screening. PLCO reported that men who underwent annual prostate cancer screenings with PSA testing and DRE had a 12 percent higher incidence of prostate cancer, but the same rate of death from the disease as the control group.

While the ERSPC showed a 20 percent (one in five) reduction in the number of deaths from prostate cancer in men 55 to 69 years old, the researchers determined that the results were not sufficient to justify population-based screening. These studies also showed there were harms associated with follow up of abnormal screening tests and with treatments.

Around this time, the United States Preventive Services Task Force (USPSTF) also recommended against PSA to screen for prostate cancer due to the number of men harmed compared to the number of lives saved. USPSTF found that in men aged 55-69, we would expect five deaths per 1,000 from prostate cancer without PSA screening, while men in the same age range who did receive a PSA screening would experience four to five deaths. Additionally, approximately 10 percent of those in the study showed a false positive, but no evidence of the disease was found present after invasive testing like a biopsy – leading to high levels of anxiety and unnecessary tests. Furthermore, another 10 percent who received a true positive PSA result (meaning they had the disease) were at risk for serious and sometimes fatal complications related to further treatment.

While the PSA blood test itself does not directly cause the above problems, it can certainly open the door to these issues. In its analysis, the USPSTF concluded that the small benefit – one life saved per 1,000 screened – does not outweigh the potential risk or harm the PSA test may cause.

These findings led the American Urological Association (AUA) to be more conservative in its recommendations for these screenings. They recommended that men under 40 or over 69 should not have the PSA screening, and men ages 55-69 should consider the test but not more than every two years.

So how do I advise patients who want to know whether they should have their PSA checked? In my practice, I often reference the 2013 AUA guidelines and generally recommend the following:

If you think you are experiencing new or changing symptoms of prostate cancer (such as a need to urinate frequently, especially at night; painful or burning urination; blood in urine or semen; and/or frequent pain or stiffness in the lower back, hips, or upper thighs) speak with your physician to determine whether PSA testing is appropriate for you.

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About Dr. David Rubin

Dr. David Rubin joined Atrius Health in 2005. He practices adult internal medicine at our Wellesley office. Prior to his career in medicine, he worked with an interactive advertising and marketing agency designing web sites for companies such as AT&T and John Hancock. His interests include preventive medicine, medical informatics, and clinical process improvement.

Comments

  1. It’s wonderful to see the the evidence-based arguments against PSA screening so clearly laid out. It would be great if Dr Rubin could do the same thing for mammograms. I continue to get regular pressure from my doctor (who is otherwise great) and from Atrius/Harvard Vanguard (in the form of regular reminders) to have an annual mammogram, despite the lack of evidence that mammograms reduce mortality from cancer overall.

    Comment by Katharine Park on July 2, 2016 at 9:43 pm

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