ABSTRACT
Several studies have indicated a link between chronic fatigue syndrome (CFS) and cancer, most of them based on anecdotal observations. We have attempted to use more population-based data to determine if the reported relationship is meaningful. Two outbreaks of a fatiguing illness which included well documented cases of CFS were evaluated ten years after the reported outbreak for long-term effects, particularly cancer. We found an unusual pattern of cancer which, in view of an increased incidence of brain tumors and non-Hodgkin's lym-phoma (NHL) reported in other studies involving CFS, indicates the need for further study. At the present time this link, which is often presumed to be due to immune dysfunction, has not yet been documented. Not all CFS patients have apparent dysregulation of the immune system and a single causative agent is highly unlikely, making the study of two heterogeneous illnesses, CFS and cancer, highly problematic. With the continuing focus on subgroups, however, this area of research may prove to be more productive.