## Diagnosis of Prostate Cancer: Investigation of Choice ### Gold Standard for Diagnosis **Key Point:** Transrectal ultrasound (TRUS)-guided prostate biopsy is the gold standard investigation for confirming prostate cancer when PSA is elevated and/or DRE findings are suspicious. ### Why TRUS-Guided Biopsy? 1. **Direct tissue diagnosis** — provides histopathological confirmation 2. **High sensitivity and specificity** — 90–95% detection rate for clinically significant cancer 3. **Allows Gleason grading** — essential for prognosis and treatment planning 4. **Procedural safety** — minimally invasive with low morbidity when performed with antibiotic prophylaxis ### Typical Biopsy Protocol - **Sampling:** 10–12 cores (extended template) - **Guidance:** Real-time ultrasound visualization - **Anesthesia:** Local anesthetic (periprostatic nerve block) - **Indications for biopsy:** - PSA > 4 ng/mL (or age-adjusted cutoff) - Suspicious DRE findings - PSA density > 0.15 ng/mL/cm³ - PSA velocity > 0.75 ng/mL/year ### Role of Other Investigations | Investigation | Purpose | When Used | |---|---|---| | **MRI pelvis** | Local staging, biopsy guidance in selected cases | After biopsy confirmation; not for initial diagnosis | | **CT pelvis/abdomen** | Distant staging (nodes, metastases) | Staging after diagnosis, not diagnostic | | **Bone scan** | Detect skeletal metastases | High-risk disease (PSA > 20, Gleason ≥ 8) | | **PSA level** | Screening, risk stratification | Adjunct, not diagnostic | **High-Yield:** TRUS biopsy is NOT used for screening (PSA is the screening tool) but is mandatory for diagnosis once suspicion is raised. **Clinical Pearl:** Negative biopsy does not exclude cancer — repeat biopsy may be needed if clinical suspicion remains high (e.g., rising PSA, persistent DRE abnormality).
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