Advancing Education, Research, and Quality of Care for the Head and Neck oncology patient.
Objectives: Osteoradionecrosis of the jaw (ORNJ) is a challenging complication following radiation therapy (RT) for head and neck cancer (HNC), with incidence rates ranging from 3.2% to 10.3%. It remains uncertain whether ORNJ promotes colonization by opportunistic pathogens or if altered oral microbiota plays a role in its onset. This study seeks to characterize the microbial landscape in ORNJ.
Study Design: Retrospective cohort.
Methods: This study included patients aged 18 and older, diagnosed with ORNJ and treated within the UNC health system in 2023.
Results: Fifty-five patients met inclusion criteria: 24.3% current smokers, 75.6% former smokers. Among comorbidities, 5 (9.1%) patients had osteoporosis, while 3 (5.5%) had osteopenia and rheumatoid arthritis. 45 (80.4%) underwent surgical resection. The average radiation dose was 6202 ± 1300 cGy, with 71.7% of patients receiving intensity-modulated radiation therapy (IMRT). The mean interval from the last day of radiation to ORNJ diagnosis was 4.7 years. Notani Stage III ORNJ was the most common diagnosis (56.4%), with spontaneous onset in most cases; only 16 cases had identifiable inciting factors. Fistulae were present in 43.6% of cases, and pathological fractures in 41.8%. Microbial cultures were obtained from 38 patients, totaling 67 samples. Unspeciated oral flora (37.3%) and mixed anaerobes (22.4%) were frequently identified. Streptococcus species were the most prevalent isolate (21.8%), followed by Actinomyces (11.9%) and Staphylococcus species (9.0%). Additional bacteria included Pseudomonas aeruginosa (n=2) and Enterobacter cloacae (n=2), with 8 cultures showing no growth. Susceptibility testing, conducted on 10 samples, revealed resistance primarily to Ceftriaxone (5 cases) and Erythromycin (3 cases). Resistance was also observed to Amoxicillin/Clavulanate and Ampicillin/Sulbactam in 4 cases.
Conclusions: The microbial landscape in ORNJ is characterized by a predominance of unspeciated oral flora, mixed anaerobes, and Streptococcus species. The occurrence of antibiotic resistance in this population underscores the need for targeted antimicrobial stewardship. Future studies may clarify the role of oral microbiota in ORNJ pathogenesis, potentially guiding prophylactic and therapeutic interventions in HNC patients undergoing RT.