Nasopharyngeal radium irradiation: the Washington County, Maryland, study

Although there have been many studies of cancer risk associated with a variety of x-ray treatments for benign conditions of the head and neck, little is known about the possible long-term health consequences of nasopharyngeal radium irradiation. This treatment results in minimal radiation exposure to the thyroid gland, which is the focus of much of the research regarding other head and neck irradiation. With nasopharyngeal radiation, on the other hand, exposure to the pituitary gland and the nasopharynx in the area immediately adjacent to the application site may have been substantial. In 1975 a follow-up study was undertaken in Washington County, Maryland, of 2925 persons who were treated at the Health Department's Clinic for the Prevention of Deafness in Children between 1943 and 1960. Of these, 904 persons had been treated with nasopharyngeal radium. After an average of 24 years of follow-up, an excess risk from brain cancer was suggested on the basis of three cases of cancer occurring in the treated group and none occurring in those who were not treated. This finding could have resulted by chance. Other results were consistent with a potential pituitary effect of radiation, but interpretation is limited by the absence of clinical and laboratory data. The history of the study is reported along with an overview of study methods and results.