Prostate cancer is one of the most common malignant tumors in men, and early screening and diagnosis are crucial for improving cure rates. Commonly used clinical screening indicators include prostate-specific antigen (PSA), the Prostate Health Index (PHI), prostate cancer gene 3 (PCA3), and imaging examinations. However, these indicators are often influenced by various factors, which may lead to false-positive or false-negative results. This article will analyze the key factors affecting prostate tumor markers from physiological, pathological, iatrogenic, and detection technology perspectives.

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I. Physiological Factors: Not All Abnormalities Indicate Cancer

1. Age and Race

PSA levels naturally increase with age. The normal PSA value for men over 50 can be extended to 4.0 ng/mL, and for those over 70, it may even reach 6.5 ng/mL. Additionally, baseline PSA levels are generally higher in African American men compared to Asian and Caucasian men.

2. Prostate Volume and Sexual Activity

Benign prostatic hyperplasia (BPH) can cause an increase in PSA. Studies show that for every 1 mL increase in prostate volume, PSA rises by approximately 4%. Furthermore, PSA testing within 24-48 hours after ejaculation may result in a temporary elevation due to glandular congestion.

II. Pathological Factors: Beware of Interference from Non-Cancerous Diseases

1. Prostatitis and Infection

Acute prostatitis can cause PSA levels to soar above 20 ng/mL, sometimes even reaching hundreds. Chronic inflammation can also lead to persistent mild elevation. Urinary retention, catheterization, or compression of the prostate during a digital rectal exam may also cause a transient rise in PSA.

2. Other Urinary System Diseases

PSA may be abnormal in patients undergoing cystoscopy, those with urinary tract stones, or those with renal failure. Comprehensive judgment should be made in conjunction with urinalysis, imaging, and other tests.

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III. Iatrogenic Factors: The Impact of Medications and Surgery

1. 5α-Reductase Inhibitors

Long-term use of medications such as finasteride and dutasteride for treating BPH can reduce PSA levels by approximately 50%. It is recommended to use "PSA × 2" as the reference threshold during medication.

2. Traumatic Procedures

PSA may increase and persist for 4-6 weeks after a prostate biopsy; PSA testing should be delayed for 3 months following transurethral resection of the prostate (TURP).

IV. Detection Technology: Standardized Operations to Avoid Errors

1. Sample Handling and Detection Methods

The half-life of PSA in blood is about 2-3 days. Hemolysis or improper sample storage can lead to deviations in values. The detection sensitivity of different reagent kits can vary by up to 15%.

2. Clinical Value of Free PSA (fPSA)

When total PSA is in the "gray zone" of 4-10 ng/mL, an fPSA/tPSA ratio < 16% suggests an increased risk of prostate cancer. However, acute urinary retention may lower the fPSA proportion, requiring careful differentiation.

V. Emerging Indicators and Comprehensive Assessment

1. Multiparameter Combined Detection

The PHI index, which combines PSA and fPSA, has significantly higher specificity than PSA testing alone. PCA3 gene testing is more instructive for patients with negative biopsy results but high clinical suspicion.

2. Supplementary Role of Imaging Technology

The PI-RADS scoring system of multiparametric MRI can assist in locating suspicious lesions, reducing unnecessary biopsies.

Summary and Recommendations

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Abnormal prostate tumor markers require multidimensional analysis considering the patient's medical history, medication use, testing timing, and other factors. Clinical recommendations include:

1. Avoid ejaculation, digital rectal exams, and strenuous exercise within 48 hours before PSA testing;

2. Establish individualized baseline values for patients on long-term 5α-reductase inhibitors;

3. For patients with persistently elevated PSA but a fluctuation of < 0.5 ng/mL/year, prioritize regular follow-up over immediate biopsy.

Accurate screening requires both doctors and patients to pay attention to influencing factors. Only through multi-indicator and multimodal joint assessment can reliable evidence be provided for the early diagnosis and treatment of prostate cancer.