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PHOENIX -- Osteoradionecrosis of the jaw (ORNJ) occurred more than twice as often as reported in the literature, according to a population-based study of patients treated with radiation for oral cancer.

A review of national medical records showed that 16.1% of patients had jaw complications or interventions consistent with ORNJ compared with published rates of 5% to 7%.

However, when investigators applied the definition of ORNJ to patients who had interventions associated with jaw complications, the rate approximated the published rates, as reported here at the Multidisciplinary Head and Neck Cancer Symposium.

"The rates of all jaw complications in the SEER-Medicare database are higher than reported rates from prospective and retrospective institutional reports," said Beth M. Beadle, MD, PhD, of the University of Texas MD Anderson Cancer Center in Houston. "If we limited the definition to interventions, the rates are similar to those of published reports."

Radiation therapy has documented efficacy for locoregional control of head and neck cancer, but therapy confers a substantial risk of long-term complications, even with modern delivery techniques.

ORNJ is recognized as a potential risk of radiation therapy. Prospective and retrospective single-institution studies have suggested that 5% to 7% of patients with head and neck cancer develop ORNJ following treatment with radiation.

The frequency of ORNJ in the general population of patients with head and neck cancers has not been studied extensively. Moreover, the true impact of newer radiation techniques, such as intensity-modulated radiation therapy (IMRT), on the frequency of ORNJ has not been clearly established.

In an effort to clarify the current frequency of and risk factors for ORNJ, Beadle and colleagues reviewed data from the NCI Surveillance, Epidemiology, and End Results database, linked to Medicare claims records. They searched for patients with oral cancers treated with radiation therapy during 2000 to 2007.

Using the Medicare records, the investigators identified patients who developed ORNJ, as determined by diagnostic and intervention codes associated with jaw complications.

The review produced records for 1,848 patients. During a median follow up of 2.54 years, 297 patients (16.1%) developed jaw complications following treatment with radiation therapy. The median time from treatment to jaw complication was 387 days.

The total ORNJ group comprised 226 (12.2%) patients identified by diagnostic code only, 41 (2.2%) patients identified by intervention code only, and 30 (1.6%) patients whose records had codes associated with diagnoses and interventions.

Univariate analysis identified three factors associated with the risk of ORNJ:

• Female sex (HR 0.667)
• No chemotherapy (HR 1.452)
• Lower Charlson comorbidity index (HR 0.726)

Previous studies had suggested that use of IMRT was associated with a reduced incidence of ORNJ, but that was not borne out in the study by Beadle and colleagues. The rate was lower with IMRT, but the difference did not achieve statistical significance.

Patients treated with IMRT did have a different pattern of ORNJ development as compared with patients treated with other forms of radiation therapy. Treatment with IMRT was associated with a median time to jaw event of 462 days as compared with 386 days for patients treated with other radiation therapy modalities.

The symposium is sponsored by the American Head and Neck Society, the American Society of Clinical Oncology (ASCO), the American Society for Radiation Oncology (ASTRO), and SNM.

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