Applications of experimental techniques to epidemiological studies of non-Hodgkin's lymphoma: use of archival tissues.

Archival tissues, particularly formalin-fixed paraffin-embedded tumors, have become increasingly valuable in studies of the etiology of cancer. In non-Hodgkin's lymphoma, subclassification of tumors by immunophenotyping and identification of oncogenic viruses has allowed more accurate interpretation of associated epidemiological information. One such example is adult T-cell leukemia/lymphoma, which is not a single histopathological entity and usually is associated with human T-cell lymphotropic virus, type I. In addition to confirming the diagnosis, the pattern of virus distribution, utilized recently in studies of Epstein-Barr virus and human herpesvirus-6-associated lymphoma, has suggested which tumors are more likely to have the virus playing a passenger role (virus detected in uninvolved tissues) and in which tumors the virus may have an etiological role (virus restricted to tumor cells). Preservation and cataloguing of tumors and relevant clinical and demographic data may play an increasingly important role in demographic studies.