Although radiation-induced malignancies are rare in patients who received radiation for a head and neck cancer, they can be life threatening when they develop, according to a presentation at the annual meeting of the American Academy of Otolaryngology-Head and Neck Surgery Foundation.

American researchers retrospectively reviewed patient charts from a regional tumor registry to identify patients with possible radiation-induced malignancies. The 4 criteria for inclusion were development of a tumor in a previously irradiated field, histological difference between the original and second tumor, no evidence of the second tumor at the time of radiation therapy, and a latency period between radiation therapy and development of the second tumor. Because of the extensive literature available that links radiation therapy with cancers of the skin and thyroid, patients with these types of second malignancies were excluded.

Data collected included patient demographics, primary diagnosis leading to radiation therapy, radiation-induced tumor type, tumor location, and treatment. A total of 13 patients (7 male, 6 female) met the criteria, with patient age ranging from 13 to 78 years. Of the 13 patients, 8 had received radiation for a malignancy and 5 patients were treated for benign conditions. Based on the total number of patients in the registry who had an eligible radiation history, the incidence of radiation-induced malignancy of the head and neck was estimated at 1 percent.

The most common radiation-induced malignancy was a sarcoma (8 of 13), followed by squamous cell carcinomas and adenoid cystic carcinoma (both 2 of 13), and acinic cell carcinoma (1 of 13). The most common location was the paranasal sinuses, but other locations included the pharynx, mandible, soft tissues of the neck, and the salivary glands. Latency periods ranged from 9 months to 49 years (average, 17 years). Radiation dose was documented in only 2 of the 13 cases.

The treatment of choice for radiation-induced malignancy was wide local resection. Follow-up ranged from 1 to 4 years. Of the 13 patients in the series, 8 are currently alive without disease, 4 are alive with disease, 1 patient died from his disease, and 1 patient was lost to follow up.

Because neither of the previous studies on long-term complications of radiation to the head and neck noted patient history regarding tobacco or alcohol use, the researchers in the current study did not know whether either might act as a carcinogen in development of a second tumor. In the current study, neither of the 2 patients who developed squamous cell carcinoma had a history of either tobacco or alcohol use, which made the diagnosis of radiation-induced malignancy all the more plausible, according to the authors.

The authors conclude that radiation-induced malignancy of the head and neck is a rare but life threatening complication of radiation therapy. Local and regional control of these tumors can be very difficult and the treatment of choice remains wide local excision. Because the latency period is so variable, lifelong follow-up should be the standard of care for any patient who has been treated with radiation therapy.