Space-time interaction in Hodgkin's disease in Greater Manchester.

Knox's test for space-time interaction was applied to 922 cases of Hodgkin's disease which, according to the North Western Regional Cancer Registry, had presented in 1962-76 among the population of the region known before 1974 as the South East Lancashire Conurbation. In the series as a whole, there were statistically significant excesses of pairs of patients separated by time intervals of less than a year and distances of less than 1 km. Analysis by age and sex indicated that this clustering involved (a) a trio of young females and (b) pairs involving adults over 45 years old. No evidence was detected of any clustering by histological subtype or of any tendency for cases close in space to be separated by long time intervals of specific duration. These findings lend support to the idea that at least some cases of Hodgkin's disease may be induced by an infection or other environmental influence, but they do not suggest that such an infection has a long and specific incubation period.