Impacted Tooth Management and Osteoradionecrosis Risk in NPC

Prophylactic extraction of impacted teeth before radiotherapy is performed to reduce the potential risk of dental complications and jaw osteoradionecrosis after treatment. However, whether prophylactic extraction is necessary for impacted teeth without indications for therapeutic extraction remains uncertain.

This study is designed to evaluate whether omission of prophylactic impacted tooth extraction is noninferior to conventional prophylactic extraction with respect to the risk of jaw osteoradionecrosis in patients with non-metastatic nasopharyngeal carcinoma undergoing curative-intent radiotherapy. The study will also assess the long-term clinical outcomes and safety of this tooth-management strategy.

Inclusion criteria

• Eastern Cooperative Oncology Group (ECOG) performance status of 0-1.
• Age 18-75 years, regardless of sex.
• Histologically confirmed non-keratinizing nasopharyngeal carcinoma, including differentiated or undifferentiated subtype (WHO type II or III).
• Newly diagnosed, previously untreated nasopharyngeal carcinoma with stage T1-4N0-3M0 according to the 9th edition of the American Joint Committee on Cancer/Union for International Cancer Control (AJCC/UICC) staging system.
• Presence of permanent dentition with at least one impacted third molar.
• Adequate bone marrow function, defined as white blood cell count ≥4.0 × 10⁹/L, platelet count ≥100 × 10⁹/L, and hemoglobin ≥90 g/L.
• Adequate hepatic function, defined as alanine aminotransferase and aspartate aminotransferase ≤2.5 × the upper limit of normal (ULN), and total bilirubin ≤1.5 × ULN.
• Adequate renal function, defined as blood urea nitrogen and serum creatinine ≤1.5 × ULN, or creatinine clearance ≥60 mL/min.
• Coagulation function within normal limits.
• Written informed consent provided, with willingness and ability to comply with study visits, treatment plans, laboratory assessments, and other study procedures.

Exclusion criteria

• Histopathological diagnosis other than WHO type II or III nasopharyngeal carcinoma.
• Impacted third molars with recurrent pericoronitis or inflammation due to incomplete eruption.
• Fully erupted third molars with dental caries involving the pulp.
• Impacted third molars with radiographic evidence of periapical or periodontal inflammation.
• Third molars completely impacted within the jawbone.
• History of active malignancy or other malignant tumors diagnosed within the previous 5 years, except for adequately treated non-melanoma skin cancer or carcinoma in situ.
• Previous chemotherapy, surgery (except diagnostic procedures), radiotherapy, or other antitumor treatment for nasopharyngeal carcinoma or cervical lesions.
• Patients receiving palliative treatment.
• Pregnant or breastfeeding women.
• Severe uncontrolled cardiovascular or cerebrovascular diseases.
• Severe hepatic or renal dysfunction.
• Uncontrolled diabetes mellitus.
• Severe osteoporosis, medication-related osteonecrosis/osteomyelitis, or chronic diseases requiring long-term systemic corticosteroid therapy.
• Other severe chronic debilitating diseases that may increase study risk or affect study compliance.
• History of drug abuse or alcohol dependence.
• Uncontrolled psychiatric disorders or inability to provide legally valid informed consent.
• Positive hepatitis B surface antigen (HBsAg) with hepatitis B virus DNA >1,000 copies/mL.
• Active hepatitis C virus infection (positive HCV RNA).
• Human immunodeficiency virus (HIV) infection or diagnosis of acquired immunodeficiency syndrome (AIDS).
• Active tuberculosis within the previous 1 year.
• History of active tuberculosis more than 1 year previously without documented completion of standard anti-tuberculosis treatment.
• Any other medical, psychological, social, or laboratory condition that, in the investigator's judgment, may compromise participant safety, interfere with study procedures, affect protocol compliance, or result in premature withdrawal from the study.
• Refusal or inability to provide written informed consent.