**Question:** Screening of prostate cancer is commonly done by

A. Prostate-specific antigen (PSA) test
B. Digital rectal examination (DRE)
C. Transrectal ultrasound (TRUS)
D. Prostate health index (PHI)

**Core Concept:** Prostate cancer is a common malignancy in males, and early detection can improve prognosis. Screening methods include PSA (prostate-specific antigen), DRE (digital rectal examination), TRUS (transrectal ultrasound), and PHI (prostate health index).

**Why the Correct Answer is Right:** The correct answer, A (Prostate-specific antigen test), is right because PSA is a protein produced by both malignant and benign prostate tissue. Elevated PSA levels in blood can indicate prostate cancer, benign prostatic hyperplasia (BPH), or both. PSA screening allows identification of high-risk patients for further evaluation and management.

**Why Each Wrong Option is Incorrect:**

B. Digital rectal examination (DRE) is a physical examination that evaluates the prostate for palpable abnormalities but is not a reliable screening tool due to inter-observer variability and limited sensitivity.

C. Transrectal ultrasound (TRUS) is a diagnostic imaging tool to visualize the prostate and surrounding structures but is not a screening test. It is used to guide biopsies and assess treatment response.

D. Prostate health index (PHI) is a PSA-based biomarker that combines PSA, age, and percent free PSA, improving the accuracy of prostate cancer detection. PHI is not a screening tool but a predictive tool used in clinical decision-making.

**Core Concept:** Screening for prostate cancer involves selecting the most appropriate test based on patient risk factors and clinical context. Combining multiple tests or incorporating clinical information is more accurate than relying on a single test.

**Clinical Pearl:** Early detection of prostate cancer through PSA testing and DRE should be individualized based on age, family history, and other risk factors. While PHI and TRUS can improve diagnostic accuracy, they are not screening tools but rather predictive and diagnostic tools, respectively.

In summary, screening for prostate cancer involves a combination of PSA testing, digital rectal examination, and sometimes TRUS or PHI, depending on individual patient risk factors and clinical context. PSA testing is the primary screening tool, but its limitations require clinical judgement to interpret the results.