Prostate Cancer Screening || Risks & Benefits
Cancer is bad. We don’t like Cancer. We try to avoid cancer and prevent it when we can. Unfortunately, prevention is not always possible. Since we can’t always prevent it, we try to do screening tests to identify cancer at an early stage when it is more likely that treatment is successful. Routine medical care includes things like colonoscopies for colon cancer, mammograms for breast cancer, and Pap Smears for cervical cancer. The definition of a good screening test includes a test of an asymptomatic patient that identifies a disease where an intervention can improve the outcomes.
This is where it gets confusing and complicated. Prostate cancer is prevalent in our society affecting 1 in 8 men during their lifetime or 12.5%. For many years, we have heard public service announcements and health promotion campaigns encouraging men to get prostate cancer screening involving a digital rectal exam and a Prostate Specific Antigen (PSA) test. The rectal exam is a very poor detector of cancer because we are only able to feel the very top of the prostate while 90% or more of the prostate is not able to be palpated. Leaving the PSA testing as the better detector of prostate cancer. Unfortunately, it turns out that screening may not be the best plan for most men.
12.5% of Men
Prostate cancer is not uncommon (12.5% of men), and it can be a horrible disease, causing great suffering and death. However, it turns out that prostate cancer screening is not as useful as we might hope and causes harm to many men. The United States Preventative Services Task Force (USPSTF) is a government-funded committee that performs a comprehensive review of available research data and makes recommendations on preventative health care including screening tests. The USPSTF essentially sets the standards for Health care recommendations in the United States. The USPSTF recommends AGAINST screening men over age 70 with a rating of “Grade D” which indicates doing PSA testing is more likely to cause harm than benefit. The USPSTF recommends Selective PSA testing in men aged 55-69. Grade C indicates that screening should be done on a selective basis. The recommendation acknowledges the risk of harm from testing, but that there is a very small likelihood of benefit and that it should be discussed with patients to help them make an informed decision as to whether the individual should proceed. Selective screening indicates that it is best to limit screening to people who are at higher risk for aggressive cancer.
Clarifying the Confusion
The reason why PSA screening is confusing is that not all prostate cancer is aggressive. Prostate cancer commonly occurs in men who live long lives and pass away from other causes without ever knowing that they have prostate cancer. Approximately 20% of men aged 50-59 who passed away from an unrelated cause are found to have prostate cancer on autopsy. Approximately 33% of men aged 70-79 have clinically insignificant prostate cancer on autopsy after passing away from an unrelated disease. Screening does detect prostate cancer, but it detects both dangerous prostate cancer as well as cancer that would never leave the prostate and never cause a problem. Unfortunately, some of the bad prostate cancers are aggressive enough that even with detection and treatment, patients still die from the disease. For patients aged 55-69, PSA screening will result in the prevention of 1.3 deaths for every 1000 men over 13 years. However, approximately 15% of screened patients will have false positives. The harm of false positives includes mental stress and anxiety as well as physical complications from biopsy procedures such as infection. 1% of prostate biopsies result in hospitalization to treat complications from the procedure.
There are also harms associated with the diagnosis of prostate cancer in many men who undergo treatment for cancer that never would have caused harm. Those patients with benign forms of the disease may have complications and side effects without benefit since the cancer would not have caused harm itself. 20% (1/5) of patients who have a prostatectomy become incontinent of urine. 66% (2/3) of prostatectomy patients have erectile dysfunction. 50% of patients treated with radiation for prostate cancer get erectile dysfunction. 1/6 of patients who receive radiation treatment for prostate cancer develop bowel problems including urgency and incontinence. So, when screening may save .1% lives, but will result in significant quality of life reduction, financial burden, and mental duress in many others, it is best not to do the screening on all patients. By selecting people who are at higher risk for deadly prostate cancer, we decrease harm and increase the likelihood that we may save lives.
African American men and men with first-degree relatives who have died from prostate cancer are considered the highest risk and most likely to benefit from screening. Agent Orange exposure has also been associated with prostate cancer as reflected by the VA making it a service-connected condition for exposed veterans. Prostate cancer prevalence in African Americans is approximately twice that of Caucasians. In addition, the mortality rate from prostate cancer in African American men is more than twice the mortality rate for Caucasians. Other weaker risk factors include a diet high in fat and low in vegetables and cigarette smoking. It is also reasonable to consider screening in patients that are using Testosterone replacement therapy which may accelerate prostate cancer if present. There is ongoing research investigating tools that may risk stratifying patients to help determine the benefits of PSA testing, but these have not yet been proven to be clinically useful. There may be changes in the type of lab tests available in the future, but currently, we are limited to our available technology.
What should you do?
Ultimately, the decision to do PSA screening for prostate cancer should be made by each individual patient with a discussion of the potential harms and benefits with their healthcare provider.
Paul Forman, MD
Sunshine Community Health Center
1-907-376-2273 (PANGANGALAGA)
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