Contacts among patients with hematological malignancies.

A survey was carried out in 2 country areas of New South Wales with the aim of defining contacts among patients with lymphoma, leukemia and myeloma, and of determining whether these were more numerous than among matched controls from the same localities. Cases were identified from records of the N.S.W. Central Cancer Registry and of local doctors and hospitals. 184 cases were found, corresponding to the expected number, and 145 patients, as well as the same number of controls, were interviewed. Of the 290 patients and controls surveyed 111 (38.3%) had had one or more contacts with other patients or controls (37.9% of patients and 38.6% of controls). There were 24 case-case pairs involving contacts among 33 individual patients, 23 control-control pairs involving 36 individuals, and 38 case-control pairs involving 66 individuals. A statistical analysis using a weighting system showed that numbers, closeness and duration of contacts among patients and patients did not differ significantly from those expected. These results thus provide no evidence in favor of the hypothesis that the diseases were transmitted from patient to patient in the survey areas.