To the Editor.—In the article "Radiation-Induced Parotid Cancer," Walker et al claim to present evidence that parotid cancers have been produced by irradiation of the head or neck. In addition, they propose criteria for designating a parotid tumor as radiation induced. For at least three reasons, and considering the limited nature of their retrospective study, we are disappointed to see that the authors arrived at certain conclusions.
First, the authors' analysis of their selected patients does not show an 8% incidence of radiation-induced parotid carcinoma; rather, it shows that 8% of these patients with parotid carcinoma also happened to have undergone irradiation at least two years before their parotid cancers were diagnosed. This association is random and without statistical significance. Furthermore, their Table 2 is a summary of 26 cases of parotid cancers in patients who have received therapeutic radiation, and not a summary of 26 cases of radiation-induced