Radiation Oncology Basics — MCQs

Question 1: What is the management of osteoradionecrosis?

• A. Hyperbaric oxygen
• B. Removal of sequestrum
• C. Fluoride application
• D. All of the above (Correct Answer)

Explanation: **Explanation:** Osteoradionecrosis (ORN) is a serious late complication of radiotherapy, most commonly affecting the mandible. It is characterized by bone death due to radiation-induced **hypocellularity, hypovascularity, and hypoxia (Marx’s 3H theory)**, leading to non-healing exposed bone. The management of ORN is multifaceted, involving conservative, medical, and surgical interventions: 1. **Hyperbaric Oxygen (HBO):** This is a cornerstone of treatment. It increases dissolved oxygen levels in tissues, stimulating angiogenesis and fibroblastic activity, which helps reverse the radiation-induced hypoxic state. 2. **Removal of Sequestrum (Sequestrectomy):** Surgical intervention is required to remove necrotic, infected bone (sequestrum) that acts as a nidus for infection and prevents healing. 3. **Fluoride Application:** Preventive and supportive care is vital. Radiation damages salivary glands (xerostomia), increasing the risk of radiation caries. Daily topical fluoride application is essential to maintain dental integrity and prevent odontogenic infections that could trigger or worsen ORN. **Why "All of the above" is correct:** Effective management requires a combination of improving tissue oxygenation (HBO), surgical debridement of dead bone, and strict oral hygiene/caries prevention (Fluoride) to arrest the progression of the disease. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site:** Mandible (due to lower vascularity compared to the maxilla). * **Marx’s Protocol:** Often involves 20–30 sessions of HBO before surgery and 10 sessions after. * **PENTOCLO Protocol:** A newer medical management involving Pentoxifylline, Tocopherol (Vitamin E), and Clodronate. * **Prevention:** All necessary dental extractions should ideally be completed **at least 2–3 weeks before** starting radiotherapy.