prostate cancer
Summary
Prostate cancer is the most common non-cutaneous cancer in men, typically arising in the peripheral zone of the prostate and often diagnosed via elevated PSA and/or abnormal DRE (asymmetric, nodular, indurated gland). Most cases are adenocarcinomas that grow slowly, but risk increases with age, African American ethnicity, and family history. Diagnosis is confirmed by biopsy with Gleason scoring, and treatment ranges from active surveillance to prostatectomy, radiation, or androgen deprivation therapy depending on stage and grade.
Detail
Prostate adenocarcinoma originates predominantly in the peripheral zone (posterior lobe), making it palpable on digital rectal exam (DRE) as an asymmetric, hard, nodular prostate—unlike BPH which arises in the transition zone and causes diffuse, symmetric enlargement. Risk factors include advancing age, African American race, family history, and possibly high-fat diet; BRCA2 mutations increase risk. Screening involves PSA (prostate-specific antigen, a serine protease produced by prostate epithelium) though it lacks specificity (can be elevated in BPH, prostatitis, and after ejaculation/DRE). Diagnosis requires transrectal ultrasound-guided biopsy; Gleason grading system assesses architectural differentiation (scored 1-5 in two most representative areas, summed for total score, now often reported using Grade Groups 1-5) and is the strongest prognostic indicator. Common metastatic sites include bone (osteoblastic lesions, particularly axial skeleton) via Batson venous plexus, presenting with back pain and elevated alkaline phosphatase. Tumor markers: PSA for monitoring, prostatic acid phosphatase (PAP) historically used. Treatment stratified by risk: low-risk/localized disease may undergo active surveillance; intermediate/high-risk localized disease treated with radical prostatectomy or radiation therapy (external beam or brachytherapy); metastatic/advanced disease treated with androgen deprivation therapy (GnRH agonists like leuprolide, GnRH antagonists, or bilateral orchiectomy), often combined with androgen receptor antagonists (e.g., bicalutamide) or CYP17 inhibitors (abiraterone) for castration-resistant disease. Complications of treatment include erectile dysfunction, urinary incontinence (prostatectomy), and radiation proctitis/cystitis. Key USMLE associations: PSA elevation, Gleason score prognostic significance, osteoblastic bone metastases, and distinguishing from BPH clinically and histologically.
Sources
- First Aid for the USMLE Step 1
- Robbins and Cotran Pathologic Basis of Disease
- UpToDate: Prostate Cancer
- AUA Guidelines on Prostate Cancer Screening and Management
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