Cancer incidence after childhood nasopharyngeal radium irradiation: A follow-up study in Washington County, Maryland

A population from a hearing clinic in Washington County, Maryland, in 1943- 1960 was followed to assess the risk of developing neoplasms from radium tr eatment of the nasopharynx for adenoid hypertrophy. Of the 2,925 subjects w ho attended the clinic, 904 received radium treatment. A nonconcurrent pros pective study compared the cancer incidence among the irradiated persons wi th that among persons with other treatments. Seven brain tumor cases (three malignant and four benign) were identified in the irradiated group versus none in the nonirradiated group (relative risk = 14.8, 95% confidence inter val: 0.76, 286.3). A nonsignificant excess risk of thyroid cancer was detec ted in the irradiated group based on two cases in the exposed group and one case in the nonexposed group (relative risk = 4.2, 95% confidence interval : 0.38, 46.6). Decreased risks of breast cancer, female genital cancers, an d prostate cancer were observed among the irradiated individuals, although these deficits were not statistically significant individually. The decreas ed risk of sex hormone-related cancers in the irradiated group suggests pos sible radiation damage to the pituitary, with consequent reduction in pitui tary hormone output and alterations in sexual and other hormonal developmen t in early life. This hypothesis needs further evaluation.