## Investigation of Choice for Prostate Cancer Diagnosis **Key Point:** Transrectal ultrasound (TRUS)-guided prostate biopsy is the gold standard for histological confirmation of prostate cancer when clinical suspicion is high. ### Clinical Context This patient has: - Elevated PSA (>4 ng/mL, with 8.5 being moderately elevated) - Abnormal DRE findings (hard, irregular prostate) - Lower urinary tract symptoms These findings warrant tissue diagnosis to confirm malignancy. ### Why TRUS-Guided Biopsy? | Feature | TRUS-Guided Biopsy | Other Modalities | |---------|-------------------|------------------| | **Diagnostic yield** | 90–95% sensitivity for cancer detection | MRI: staging tool, not diagnostic | | **Tissue confirmation** | Provides histology + Gleason grading | PSA density: indirect marker only | | **Cost-effectiveness** | Relatively inexpensive, office-based | CT: for metastatic staging, not diagnosis | | **Procedural time** | 15–20 minutes | MRI: 30–45 minutes, not first-line | | **Standard of care** | Guideline-recommended first-line | All others: adjunctive only | **High-Yield:** TRUS biopsy should be performed when PSA >4 ng/mL (or PSA density >0.15) AND abnormal DRE, OR PSA velocity >0.75 ng/mL/year. ### Role of Other Investigations 1. **MRI pelvis with endorectal coil** — Used for: - Staging (local extent, seminal vesicle involvement) - Treatment planning (radiation vs. surgery) - NOT for initial diagnosis 2. **CT scan** — Reserved for: - Detecting metastatic disease (bones, distant lymph nodes) - Staging after biopsy confirmation 3. **PSA density** — Calculated as PSA/prostate volume; helps risk stratify but does NOT diagnose cancer. **Clinical Pearl:** A negative TRUS biopsy does not exclude cancer if clinical suspicion remains high; repeat biopsy or MRI-guided biopsy may be considered. [cite:Robbins 10e Ch 21]
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