PSA Screening for Prostate Cancer

Editor's note: first of two parts; read part two here. This post addresses PSA screening for prostate cancer. In part two, we describe how doctors use PSA to monitor and manage existing cancer.

How PSA Works

Prostate cells produce PSA, a protein that helps liquefy semen. Cancer cells release more PSA into the blood because they are leakier.

History and Controversy

PSA screening became widespread in the early 1990s. While it can detect early, treatable cancers and be lifesaving, it also flags many low-grade tumors that may never cause harm.

Screening Recommendations

• USPSTF: Discuss pros and cons for men ages 55–69; advise against screening over 70; no recommendation under 55.
• American Cancer Society: Begin screening Black men at age 45; consider earlier screening for those with first-degree relatives diagnosed young or with BRCA1/2 mutations.

Preparing for the Test

Avoid activities that press the prostate (biking, sexual activity) for 2–3 days prior. Prostatitis, infections, or benign prostatic hyperplasia can also raise PSA unrelated to cancer.

Interpreting PSA Levels

PSA above 4 ng/mL is generally considered abnormal, but cutoffs vary by age: for example, 3.5 ng/mL in a man in his 40s is abnormal, while 5.5 ng/mL in a man in his 60s may be acceptable. PSA values lie on a continuum, with higher levels indicating higher cancer risk.

Test Limitations

PSA testing can miss cancers: up to 15% of men with PSA under 4 ng/mL may still have prostate cancer, including clinically significant tumors. Some high-grade cancers may produce less PSA.

Current Diagnostic Approach

An elevated PSA is often followed by an MRI to pinpoint suspicious regions. In some centers, a negative MRI may allow men to avoid an initial biopsy. If MRI findings are positive, a targeted biopsy is performed. Confirmed low-grade cancers may enter active surveillance, while higher-grade cancers receive immediate treatment.

Moving Forward

This risk-adapted approach seeks to identify cancers that truly need treatment while reducing overdiagnosis of insignificant tumors. In part two, we will explore advanced PSA-based tests and monitoring strategies for patients under active surveillance or treatment.