A 72-year-old man from Mumbai presents with bone pain in the lower back and pelvis for 3 months. He reports fatigue and unintentional weight loss (5 kg in 2 months). PSA is 145 ng/mL. Bone scan shows multiple osteoblastic lesions in the lumbar spine, pelvis, and femur. CT abdomen/pelvis reveals a large prostate mass with invasion into the bladder base and bilateral pelvic lymph node enlargement (largest 3 cm). What is the most appropriate initial treatment?

Explanation

## Clinical Presentation This patient has **metastatic castration-sensitive prostate cancer (mCSPC)** with: - Extremely elevated PSA (145 ng/mL) - Osteoblastic bone metastases (lumbar spine, pelvis, femur) - Locally advanced primary tumor (T4: bladder invasion) - Regional lymph node metastases (N1) - Constitutional symptoms (fatigue, weight loss) ## Disease Classification **Key Point:** Metastatic prostate cancer is classified as: - **mCSPC** (metastatic castration-sensitive): newly diagnosed metastatic disease; hormone-responsive - **mCRPC** (metastatic castration-resistant): progression despite ADT; requires second-line agents This patient has **newly diagnosed metastatic disease** → mCSPC. ## Treatment Algorithm for mCSPC ```mermaid flowchart TD A[Metastatic prostate cancer]:::outcome --> B{Castration-sensitive<br/>or resistant?}:::decision B -->|Castration-sensitive<br/>newly diagnosed| C[ADT monotherapy<br/>GnRH agonist/antagonist<br/>+ antiandrogen]:::action B -->|Castration-sensitive<br/>high-volume disease| D[ADT + docetaxel<br/>or ADT + abiraterone]:::action B -->|Castration-resistant| E[Second-line agents:<br/>abiraterone, enzalutamide,<br/>docetaxel, cabazitaxel]:::action C --> F[Assess response<br/>PSA, imaging at 3 months]:::action D --> F E --> G[Monitor for progression]:::action ``` ## Why ADT (with or without chemotherapy)? **High-Yield:** The **CHAARTED trial** (2015) and **STAMPEDE trial** (2016) demonstrated that for **high-volume metastatic disease** (visceral metastases or ≥4 bone lesions with at least 1 outside the pelvis/spine), **ADT + docetaxel** improves overall survival compared to ADT alone. **Clinical Pearl:** This patient has: - Multiple bone metastases (lumbar spine, pelvis, femur) → high-volume disease - Locally advanced primary (T4) - Significant symptom burden However, the **single best initial step** is **ADT** (GnRH agonist/antagonist ± antiandrogen). Docetaxel is added if high-volume disease is confirmed or if there is rapid progression on ADT alone. ## Why NOT the Other Options? | Option | Why Wrong | |--------|----------| | **Radical prostatectomy** | Contraindicated in metastatic disease. Surgery is for localized/locally advanced disease only. Metastatic disease requires systemic therapy. | | **Chemotherapy alone** | Docetaxel is never given without ADT in newly diagnosed mCSPC. ADT is the backbone of treatment. | | **Palliative radiotherapy alone** | Radiotherapy addresses bone pain but does not treat systemic disease. It is adjunctive, not primary therapy. | **Mnemonic:** **CHAARTED** = **C**hemotherapy + **H**ormonal therapy for **A**dvanced **A**denocarcinoma of the **R**ostate: **T**axane-based **E**fficacy **D**emonstrated. [cite:Harrison 21e Ch 97] [cite:Campbell-Walsh Urology 12e Ch 105]