Radiation Cancer. A Review with Special Reference to Radiation Tumours in the Pharynx, Larynx, and Thyroid

Twenty-four cases of radiation cancer in the deep tissues of the neck have been recorded in the literature; of these 18 have developed in the pharynx, five in the larynx and one in the thyroid. A further 18 cases of radiation cancer of the pharynx are reported here. Analysis of all patients with radiation tumours in the pharynx shows that the relationship between age, sex and site is similar to that of spontaneous malignant disease of the pharynx, but that an unusually high proportion of patients develop radiation cancer between the ages of 40 and 50. Reasons are given for believing that radiation is likely to prove carcinogenic when other factors which predispose to cancer are present. Radiation cancer of the pharynx has occurred after a long latent interval (10 to 35 years: mean 25 years) in patients who were irradiated for thyrotoxicosis or tuberculous lymphadenitis. A few patients did not show signs of severe radiation damage to the skin or subcutaneous tissues. Twelve patients who developed cancer of the pharynx following previous irradiation for thyrotoxicosis were seen at Manchester between 1947 and 1954. It has been shown that in this group of patients the observed incidence of cancer of the pharynx is significantly greater than the expected incidence. Certain aetiological factors which might account for the development of cancer in the pharynx in preference to the thyroid, after irradiation of the neck, have been discussed. It is concluded that the possible development of thyroid carcinoma in patients treated with 131I for thryotoxicosis cannot be assessed until long-term survival figures for an adequate number of patients treated by this method are available.