Prostate Cancer Screening - A Public Service Announcement About PSAs

Prostate cancer screening is a fairly controversial topic for public health and the medical community. When looking at the balance between the benefits and the risks, the evidence shows it is heavier on the side of risks. In short, prostate cancer screening is not very effective at saving lives, but is unfortunately quite effective at causing harms. More on this a little later. 

First, let's have just a short discussion on the burden of the disease. Other than minor skin cancers, prostate cancer is the most common type of cancer diagnosed in men, with around 170,000 being diagnosed with prostate cancer each year.¹ This number is pretty high, but lower than the actual number of men who develop the disease. There are many men who develop prostate cancer and never know it; as up to 70% of men over 80 years old who died of other causes were found to have prostate cancer on autopsy.² Just under 30,000 men in the United States die of prostate cancer per year, making this the second leading cause of cancer death in men.¹ 

So, this can clearly be a very bad disease. It would be fantastic if we had a more effective means of screening for this disease, but unfortunately we don’t. The best screening tool that we have is a blood test called a PSA (prostate-specific antigen). This is a protein that is often elevated in the blood of an individual with prostate cancer, but the effectiveness of the PSA for screening is not great. There are some false negatives, and many false positives. Here are the numbers: 

For every 1000 men between the ages of 55-69 who undergo PSA testing for 13 years, it is estimated that 240 men would have at least one positive PSA test. Over 200 of these 1000 men (1 in 5!) would undergo a prostate biopsy, and 2 would be hospitalized for complications from the biopsy. Biopsies are performed transrectally and are obviously uncomfortable, but also carries their own share of risks (infection, bleeding).

Of the 200+ men biopsied, 100 would be diagnosed with prostate cancer, and 80 would eventually undergo treatment with surgical removal of the prostate (called radical prostatectomy) or radiation. 50 of these men treated will have sexual dysfunction (usually impotence) and 15 will have urinary incontinence. After all of this, 5 men will still die of prostate cancer despite diagnosis and treatment.

That’s a lot of harm done because of screening and subsequent treatment. Keep this in mind when comparing the harms against the benefits, which are:

Of the 1000 men screened, only 1, or at the most 2, will avoid dying of prostate cancer because of testing. About 3 will avoid having prostate cancer that spreads to other areas of the body.³ (Find a more in-depth explanation here.)

So, with this evidence in mind, there are no medical societies that strongly encourage prostate cancer screening routinely. For several years before May 2018, the United States Preventive Services Task Force (USPSTF) actively recommended against screening (a “D” rating). With the May 2018 bulletin, they softened their stance, and made PSA-based screening a level “C“ rating. This means that the test “could be offered or provided for selected patients depending on individual circumstances”.³ 

This aligns the Task Force more closely with the American Cancer Society, and the American Urological Association. Both of these groups acknowledge the limitations of screening with a PSA, and recommend informed decision-making to take place before screening.^4-5.  (You can find the ACS recommendations here, and for the AUA recommendations here.)

While considering screening, men should factor in historical points that increase their risk. These include: 

1. Having first-degree relatives who have been diagnosed with prostate cancer younger than age 65.
2. African American race.
3. If you have a known genetic syndrome that increases your risk for prostate cancer (such as the BRCA gene mutation, especially BRCA-2).

Screening may be more beneficial to you if you are affected by these factors, as your pre-test probability of having the disease is higher. In fact, the ACS recommends contemplating screening at an earlier age if you do have certain risk factors. Otherwise, for men at average risk, the age window when screening is the most beneficial 55-69. The USPSTF recommends against screening from 70 on, as the benefit diminishes even further. The other two societies make a case for the option of extending screening for exceptionally healthy men, with a life expectancy of at least 10 years. 

Hopefully you can now see why it is so important to be informed about this disease and the PSA before you have it done. Many men who come into the clinic can feel “obligated” to undergo testing. Frequently this is at the urging of someone who loves them and wants the best for them, and many times it is due to a desire to maintain their health as best as possible. Unfortunately, very few of them know all of the implications of screening, and even more troubling is that many doctors do not explain the implications very well. This is really a shame, because men definitely should have the right to make an informed decision based on solid information. The purpose of this article is to help provide this information. 

So please pass this along! Men need to be informed of their options, and you could be the one to help.

Sources:

1. U.S. Cancer Statistics Working Group. United States Cancer Statistics: 1999–2014 Incidence and Mortality Web-based Report. Atlanta (GA): Department of Health and Human Services, Centers for Disease Control and Prevention, and National Cancer Institute; 2017

2. Katy J.L. Bell, Chris Del Mar, Gordon Wright, James Dickinson, Paul Glasziou. Prevalence of incidental prostate cancer: A systematic review of autopsy studies. International Journal of Cancer. March 26, 2015
3. Final Recommendation Statement: Screening for Prostate Cancer and Final Evidence Review: Screening for Prostate Cancer. U.S. Preventive Services Task Force. May 2018. www.uspreventiveservicestaskforce.org
4. American Cancer Society Recommendations for Prostate Cancer Early Detection.  The American Cancer Society medical and editorial content team. April 2016. https://www.cancer.org
5. H. Ballentine Carter, Peter C. Albertsen, Michael J. Barry, Ruth Etzioni, Stephen J. Freedland, Kirsten Lynn Greene, Lars Holmberg, Philip Kantoff, Badrinath R. Konety, Mohammad Hassan Murad, David F. Penson and Anthony L. Zietman. Early Detection of Prostate Cancer. Reviewed and Validity Confirmed 2015. http://www.auanet.org