Comparison of Intensity-Modulated Radiation Therapy and 3D Conformational Radiation Therapy in Osteoradionecrosis Development in Head and Neck Cancer Patients

Objective: Osteoradionecrosis (ORN) is a significant complication of radiation therapy for the treatment of head and neck cancers. Currently, the incidence of ORN is estimated to be 7% among head and neck cancer patients treated with radiation therapy.¹ Advances in the delivery of radiation have allowed for improved delivery to the target zone and decreased irradiation of the surrounding healthy tissue. It was hypothesized that the utilization of and intensity-modulated radiation therapy (IMRT) would result in decreased incidence of ORN relative to 3D conformational radiation therapy (3DCRT).

Methods: A retrospective chart review was performed including all patients who were diagnosed with head and neck cancer at the Cleveland Clinic Head and Neck Institute and received radiation therapy between January 1, 2010 and Feb 29, 2016. Approval for data collection and analysis was obtained from Cleveland Clinic Institutional Review Board, IRB #4311 and IRB #16-232. Patient information was collected and compiled by the Cleveland Clinic Radiation Oncology in conjunction with the Head and Neck Tumor Board and entered into a REDCap database. A total of 579 patient charts were reviewed. The location of primary tumor, diagnosis of ORN and treatment modality was recorded with review of the radiotherapy dosimetric maps. Treatment modalities included 3DCRTor IMRT +/- surgical resection and/or chemotherapy. Statistical analysis was performed using JMP Pro Version 12.

Results: Twenty one out of 579 patients (3.6%) were diagnosed with ORN of the mandible (mean age 58 years, range 46 – 75 years), with most frequent cancer type being the base of tongue cancer (7), followed by tonsil (5), floor of mouth (4), larynx (3), buccal mucosa (1), and parotid gland (1). For the sites of osteoradionecrosis, 91.7% of patients with oropharyngeal cancer (base of tongue & tonsil) developed necrosis in the posterior mandible, reflecting a higher average radiation dose in the posterior regions, whereas 67% of patients with laryngeal or mobile portion of the tongue developed necrosis in the anterior mandible. A higher average dose of radiation among patients with ORN than those without ORN (69.2 vs. 66.7 Gy, unpaired t-test p<0.05) was noted. While there was trend of increased incidence of ORN in patients treated with 3DCRT vs IMRT, this did not reach statistical significance (p>0.05). In addition, there was no statistical difference (chi-square, p>0.05) in the use of concurrent chemotherapy vs. radiotherapy alone in incidence of ORN development.

Conclusion: Similar to other studies in the current literature, this study showed that the overall incidence of ORN in head and neck cancer patients treated with radiation therapy at the Cleveland Clinic was relatively low at 3.3%². These data suggest a trend of decreased ORN in patients treated with IMRT as compared to 3DCRT. Further studies are needed to delineate local and regional risk of development of ORN.

References:

1. Nabil S, Samman N: Incidence and prevention of osteoradionecrosis after dental extraction in irradiated patients: a systematic review, International Journal of Oral and Maxillofacial Surgery 40: 229-243, ISSN 0901-5027, 2011.
2. Studer G, Studer S P, Zwahlen R A, Huguenin P, Grätz K W, Lütolf U M, & Glanzmann C: Osteoradionecrosis of the mandible. Strahlentherapie Und Onkologie, 182(5), 283-288, 2006