​Screening for prostate cancer: Are PSA blood tests reliable?

Prostate cancer is the most commonly diagnosed cancer among American men and remains the second-leading cause of cancer-related death. Up until the late 1980s, men were typically diagnosed at a late stage, when they presented with bone pain and symptoms of the cancer’s spread, known as metastases. It was rarely curable.

In the late 1980s and early 1990s, the prostate specific antigen (PSA) test, which measures a protein produced by both normal and cancerous cells in the prostate, emerged as a simple blood test to indicate the likelihood of having prostate cancer. Millions of men over the age of 50 in the U.S. who were free of signs and symptoms of the disease started regularly getting their PSA levels checked.

As a result, prostate cancer began to be diagnosed far more frequently, both in men who, if not treated aggressively, could die from the disease and men who had prostate cancers that were never destined to cause symptoms or problems. Thus began the “modern era” of prostate cancer, when tumors are more frequently diagnosed while still contained within the prostate and, therefore, more likely to be curable. Since that time, the United States has seen more than a 50 percent drop in deaths from prostate cancer in the United States. However, the full story is more nuanced.

Shortcomings of PSA

Although the early detection and diagnosis of aggressive prostate cancer is critical to improving survival, PSA cannot reliably tell the difference between slow-growing cancers that do not pose a risk and less common, potentially deadly cancers. Men with harmless cancers may then be subjected to unnecessary biopsy, as well as unnecessary treatments that may cause side effects such as impotence, incontinence, or bowel dysfunction. Screening for cancer is generally thought to be a good thing, but once the risks outweigh the benefits, the test may actually be doing more harm than good.

Due to concerns about overdiagnosis and overtreatment, in 2012, the United States Preventive Services Task Force (USPSTF) discouraged PSA screening in healthy men of all ages, a “D” recommendation.

Every man who has a life expectancy estimated to be greater than 10 years should at least have the conversation with their physician about the pros and cons of checking their PSA levels.

In May 2018, the USPSTF upgraded the recommendation to a “C,” denoting men between the ages of 55 to 69 at average risk of developing prostate cancer should discuss the benefits and harms of screening with their doctor, so they can make the best choice for themselves based on their values and individual circumstances. For men 70 and older, the USPSTF recommends against routinely screening for prostate cancer. Other groups, such as the Scott Eggener, MD, Professor of Surgery (Urologic Oncology), believes the PSA test remains valuable for potentially saving lives, but he and other urology experts at UChicago Medicine take a sensible approach. “Every man who has a life expectancy estimated to be greater than 10 years should at least have the conversation with their physician about the pros and cons of checking their PSA levels,” Eggener said. “Not every man needs a PSA, not every man with an elevated PSA needs a biopsy, and not every man with cancer necessarily needs immediate treatment.”

An Evolving Landscape

There have been tremendous strides to improve the landscape of prostate cancer screening, risk assessment, and management strategies. MRI of the prostate is the best available picture of the prostate and potential prostate cancer. Quality MRI images can be used to eliminate the need for a prostate biopsy, provide useful information to target during biopsy, and are often helpful to tailor the plan for surgery or radiation. Additionally, there are many novel blood and urine biomarkers (e.g. 4Kscore, prostate health index, SelectMDx, and others) that can be used to fine-tune the risk assessment of whether a man would benefit from having a biopsy. These tests outperform PSA and can provide men more information on whether to proceed with a biopsy or not.

Not all men diagnosed with prostate cancer require immediate treatment, as many men with low-risk cancers can safely be monitored with a strategy called active surveillance.

There is no question that men at increased risk, including African American men and anyone with a family history (first-degree relative with prostate cancer) or carriers of known cancer-related genetic mutations, such as the BRCA1/2 gene, should strongly consider prostate cancer screening, usually starting by the age of 45-50.

Screening for prostate cancer is an individual decision that a man should make with his doctor’s help based on factors such as his level of risk, overall health, life expectancy and willingness to undergo treatment in the event of a prostate cancer diagnosis.