High school contact among persons with leukemia and lymphoma

We studied frequency of contact among Connecticut high school students and teachers with leukemia and lymphoma diagnosed during or after high school from 1960 through 1971. Risk of having attended the same grade at the same school during the same year was greater among students with Hodgkin's disease (HD) than among simulated controls drawn in proportion to school enrollment (relative risk = 1.44; approximate 95% lower confidence limit = 1.05). Risk of developing HD was also greater among students enrolled simultaneously at the same school as students already diagnosed with HD than among students not so enrolled (relative risk = 2.05; 95% lower confidence limit = 1.39). However, fewer HD cases (16) were diagnosed from 1965 through 1970 at schools that formerly had patients enrolled (1959-64) than at matched schools without such patients (24). We found no evidence of increased contact among persons with non-HD lymphomas or leukemias, except between HD and non-HD lymphomas (relative risk = 1.41; approximate 95% lower confidence limit = 1.11).