Overall, Night Shift Work Not Tied to Higher Lymphoma Risk

Night shift work may increase the risk for chronic lymphocytic leukemia (CLL), according to a study published online Jan. 13 in Occupational & Environmental Medicine.

Pierluigi Cocco, M.D., from the University of Cagliari in Italy, and colleagues investigated the association between night shift work and the risk for lymphoma subtypes using data from 867 incident cases and 774 controls.

After adjusting for age, gender, education, study area, marital status, and family history of hemolymphatic cancer, the researchers found that ever working night shifts was associated with an increase in the risk for CLL (odds ratio, 1.9), which was highest after 15 to 34 years latency. There was no linear increase observed in risk by probability of exposure, years of night shift work, or lifetime number of night shifts (either rotating or permanent work schedules). There was no association between night shifts and lymphoma risk overall, B cell lymphoma or its major subtypes other than CLL, and other less prevalent B cell lymphoma subtypes combined.

"Our results suggest that chronic lymphocytic leukemia, but not lymphoma in general, nor other B cell lymphoma subtypes, might be a long-term consequence of night shift work," the authors write. "Further research is warranted to explore whether specific conditions, such as the individual chronotype and/or the shift-rotating schedule, might differentially affect the immune system, thus modulating the hypothesized effect on the risk of lymphoma and particularly CLL."