Prostate Cancer Tests

There are a number of ways to detect prostate cancer. Traditionally, a doctor would attempt to feel the prostate gland with their finger. This is called a digital rectal exam, or a DRE. With time, it become apparent that this was not a perfect test for a number of reasons. Presently, we screen for prostate cancer with a blood test called a Prostate Specific Antigen, or a PSA. This test also has its limitations. Let’s find out more about how to look for prostate cancer with these two methods.

One way to find prostate cancer is for your doctor to perform a digital rectal exam, also known as a DRE. The digital rectal exam involves a doctor using their finger to feel the prostate gland for masses or hard lumps. The doctor needs to insert their finger through the rectal to touch and feel the prostate gland. With this exam, you may feel the urge to urinate as the prostate gland lies beneath the bladder. Interestingly, 25-30% of tumors of the prostate are missed as they cannot be felt on digital rectal exam. Some are small stage 1 cancers and others cannot be reached with one’s finger.  Therefore, this is not a perfect test. In fact, the United States Preventative Services Task Force does not have a recommendation for the use of a digital rectal exam to find prostate cancer in those who are average risk.  (1) This decision for a DRE is personal one and should be based upon you risk for this disease and discussions with your doctor.

Another way to find prostate is to perform a blood test called the Prostate Specific Antigen, also known as a PSA. The PSA is a protein that is found in the prostate gland. When there is injury to the prostate gland, the PSA can leak into the blood and be measured. Unfortunately, a PSA is also not a perfect test as there as a number of conditions, in addition to cancer, that can cause leakage of the PSA protein. This includes being intimate, riding a bike for a prolonged period of time or having an infection in the prostate gland.  Even having an enlarged prostate, which is very common, can cause a rise in the PSA level. Since about 90% of all prostate cancers are found in men over the age of 55, the United States Preventative Services Task Force recommends screening men over the age of 55 with a PSA blood test. (1) The American Cancer Society goes a step further and recommends beginning screening discussions at age 40 to 45 in those at high risk of developing prostate cancer; this is including African American men and men with a first-degree relative, such as a father, with prostate cancer diagnosed before age 65. (2)

In all, the digital rectal exam seems to have fallen out of favor as a method to search for prostate cancer for the average risk man. The PSA blood has become a better approach, but this is not a perfect test either. In fact, for every 1000 PSA blood test performed, one live is saved (1) To the one man whose life is saved, the PSA is a great test. To the other 999 who had to undergoing unnecessary worry, testing and procedures, the PSA is not be a great test. Therefore, it is important to discuss your family history and risk for prostate cancer with your doctor to determine if a PSA blood test or digital rectal exam is right for you.

REFERENCES
1. US Preventive Services Task Force, Grossman DC, Curry SJ, Owens DK, Bibbins-Domingo K, Caughey AB, Davidson KW, Doubeni CA, Ebell M, Epling JW Jr, Kemper AR, Krist AH, Kubik M, Landefeld CS, Mangione CM, Silverstein M, Simon MA, Siu AL, Tseng CW. Screening for Prostate Cancer: US Preventive Services Task Force Recommendation Statement. JAMA. 2018 May 8;319(18):1901-1913.
2. Wolf AM, Wender RC, Etzioni RB, Thompson IM, D’Amico AV, Volk RJ, Brooks DD, Dash C, Guessous I, Andrews K, DeSantis C, Smith RA; American Cancer Society Prostate Cancer Advisory Committee. American Cancer Society guideline for the early detection of prostate cancer: update 2010. CA Cancer J Clin. 2010 Mar-Apr;60(2):70-98