A 42-year-old woman with stage IB2 cervical squamous cell carcinoma (SCC) is deemed suitable for concurrent chemoradiation therapy. Which agent is the drug of choice for radiosensitization during pelvic radiotherapy?

Explanation

## Concurrent Chemoradiation for Invasive Cervical Cancer ### Standard of Care: Cisplatin-Based CCRT **Key Point:** Cisplatin is the gold-standard radiosensitizing chemotherapy agent for concurrent chemoradiation (CCRT) in locally advanced cervical cancer (stages IB–IVA). It is the only agent with robust level-1 evidence demonstrating survival benefit. **High-Yield:** Cisplatin mechanisms in CCRT: 1. **Radiosensitization:** Inhibits DNA repair, potentiates radiation-induced double-strand breaks 2. **Direct cytotoxicity:** Platinum-DNA adducts cause apoptosis 3. **Synergy with radiation:** Enhanced cell kill compared to either modality alone ### Landmark Evidence **Clinical Pearl:** The landmark meta-analysis by the Cochrane Collaboration and multiple RCTs (GOG 165, RTOG 90-01) demonstrated that concurrent cisplatin-based CCRT improves overall survival by ~10–12% and disease-free survival compared to radiation alone in stages IB–IVA cervical cancer. **Mnemonic:** **CCRT-C** = **C**oncurrent **C**hemotherapy **R**adiation **T**herapy with **C**isplatin ### Dosing and Schedule **High-Yield:** Standard regimen: - Cisplatin 40 mg/m² IV weekly during 5–6 weeks of pelvic radiotherapy - Total cumulative dose: 200–240 mg/m² over the course - Concurrent with external beam radiation therapy (EBRT) ± brachytherapy ### Comparison with Alternatives | Agent | Mechanism | Evidence in Cervical Cancer | Role | |-------|-----------|---------------------------|------| | Cisplatin | Platinum alkylator, radiosensitizer | Level 1 (RCT); OS benefit proven | **Standard CCRT agent** | | Paclitaxel | Microtubule stabilizer | Phase II data; less radiosensitization | Adjuvant or recurrent disease | | Bevacizumab | Anti-VEGF monoclonal Ab | Phase III (GOG 240); for recurrent/metastatic | Not used in primary CCRT | | Topotecan | Topoisomerase I inhibitor | Limited data in cervical cancer | Salvage therapy, not primary CCRT | **Warning:** Do not confuse concurrent CCRT (cisplatin + radiation for primary disease) with sequential chemotherapy (paclitaxel/cisplatin) used for recurrent/metastatic cervical cancer. ### Contraindications & Monitoring **Clinical Pearl:** Cisplatin toxicity during CCRT includes: - Nephrotoxicity (requires aggressive hydration) - Ototoxicity (high-frequency hearing loss) - Peripheral neuropathy - Myelosuppression Baseline renal function, audiometry, and CBC monitoring are essential. [cite:Harrison 21e Ch 297]