Second primary cancer after irradiation of laryngeal cancer

Thirty (5.6%) of 535 patients followed 5-25 years after treatment of cordal carcinoma (T1A,B) developed a second primary laryngeal carcinoma. When analyzed by treatment modality, 3.9% of operated cases and 9% of irradiated cases formed new laryngeal or laryngopharyngeal malignancies. An explanation by radiation-induced carcinogenesis for this statistically significant difference between the two groups is discussed. It is also suggested that supervoltage radiation directed to the laryngeal mucosa may produce the diminished latent period observed between the appearance of the second primary carcinoma.