What criteria should be considered when choosing a screening test, such as the Prostate-Specific Antigen (PSA) test, for prostate cancer?

Criteria for Choosing a Prostate Cancer Screening Test

The primary criterion for selecting a prostate cancer screening test is its ability to detect clinically significant, high-grade cancers early enough to enable curative treatment while minimizing detection of indolent disease that would never threaten the patient's life. 1

Core Selection Criteria in Order of Priority

1. Detection of Aggressive Disease While Avoiding Overdiagnosis

• The fundamental goal is to identify aggressive prostate cancer early and cure it before it spreads outside the prostate, while avoiding overdetection of indolent tumors. 1
• This criterion supersedes simple sensitivity because autopsy studies demonstrate that prostate cancer may be present in 33% of men over age 50, yet most of these cancers would never become clinically apparent during the patient's lifetime. 1
• A test that detects every cancer (including all indolent disease) causes massive overdiagnosis and overtreatment, with attendant complications including incontinence, impotence, and bowel dysfunction. 1

2. Adequate Specificity to Minimize False Positives

• A screening test must have adequate specificity to avoid false-positives that lead to unnecessary biopsies, patient anxiety, and potential complications, including drug-resistant infections. 1
• PSA testing has poor specificity of only 60-70% at the conventional 4.0 ng/mL cutoff, which is a major limitation. 1
• Biomarker tests and multiparametric MRI can improve specificity and reduce unnecessary biopsies by 20-30%. 1
• At the standard PSA cut-off of 4 ng/mL, sensitivity is only 20.5% for prostate cancer—nearly 80% of cases are missed—but specificity is high at 93.6%. 2

3. Early Stage Detection with Treatment Benefit Window

• Men must have at least a 10-15 year life expectancy to potentially benefit from screening, as this is the timeframe needed for early detection and treatment to impact outcomes. 1
• The test should enable risk stratification—men with PSA <1.0 ng/mL at age 60 have <0.3% likelihood of prostate cancer death, allowing less intense follow-up. 1
• Screening offers a small potential benefit of reducing the chance of death from prostate cancer, preventing approximately 1.3 deaths per 1000 men screened over 13 years. 3

4. Practical Implementation Considerations (Secondary)

• While cost-effectiveness and wide availability are relevant factors, these are secondary to the test's ability to improve clinical outcomes without causing net harm. 1
• The test must be acceptable enough to allow shared decision-making and informed consent, as screening should never occur without patients understanding the benefits, risks, and uncertainties. 1

Critical Pitfalls to Avoid

Do Not Prioritize Sensitivity Alone

• Maximizing detection of "as many cases as possible" (Option A from your question) is explicitly the wrong approach. 1
• This leads to detection of the 33% of men over 50 who harbor prostate cancer that will never become clinically significant, resulting in overtreatment. 1

Do Not Screen Without Counseling

• Two-thirds of US men reported no discussion with physicians about advantages, disadvantages, or scientific uncertainty regarding PSA screening—this represents inappropriate use. 1
• A thorough discussion on the pros and cons of testing must be carried out between the physician and the potential participant. 4

Do Not Screen Men with Limited Life Expectancy

• Screening men over 75 years or those with <10 year life expectancy substantially increases overdetection without mortality benefit. 1
• The harms of screening in men older than 70 years are at least moderate and greater than in younger men because of increased risk of false-positive results, diagnostic harms from biopsies, and harms from treatment. 3

Algorithm for Test Selection

When evaluating any prostate cancer screening test:

1. First assess: Does it preferentially detect high-grade, clinically significant cancers over indolent disease? 1
2. Second assess: What is the specificity—will it avoid excessive false positives and unnecessary biopsies? 1
3. Third assess: Can it risk-stratify patients to allow personalized screening intervals? 1
4. Fourth assess: Is the patient appropriate for screening (age 45-75 years, life expectancy ≥10-15 years)? 4, 1
5. Finally consider: Cost and availability only after clinical performance criteria are met. 1

The correct answer to your question is Option B (detect early cancer stage), but only when qualified as "detect early-stage aggressive cancer while avoiding indolent disease detection." 1 Option A (detect as many cases as possible) is explicitly wrong, and Option C (inexpensive and widely available) is a secondary consideration after clinical performance. 1