Occupational risk factors for subgroups of non-Hodgkin's lymphoma

The non-Hodgkin's lymphomas (NHL) are a diverse group of neoplasms of the lymphatic system whose incidence has been increasing in recent years. The Centers for Disease Control Selected Cancers Study, a population-based case-control study of several cancers, included a large number of cases of NHL and a pathology review, providing a rare opportunity to study risk factors for groups of NHL subtypes. We examined the relation between occupational exposures and three subgroups of NHL: small cell diffuse lymphomas (N = 185), follicular lymphomas (N = 268), and large cell diffuse lymphomas (N = 526). There were 1,659 controls available for comparison. After controlling for demographic variables and previously identified risk factors for NHL, we observed two interesting associations, one between solvent exposure and small cell diffuse lymphomas [odds ratio (OR) = 1.60; 95% confidence interval (CI) = 1.10-2.20], and the other between meat packaging/processing and follicular lymphomas (OR = 1.60; 95% CI = 0.99-2.60). The results of this exploratory analysis are primarily negative. Our lack of positive findings may indicate that the subgroups of NHL used may not be etiologically distinct and that further work needs to be done to develop an NHL classification system that is etiologically informative and useful for epidemiologic studies.