Sunlight deprivation, influenza and leukaemia

It has been hypothesized that successive genetic damages – a prerequisite for leukaemia – could emerge as a combined effect of vitamin D deficiency due to winter darkness, and influenza epidemics occurring during the same season. This hypothesis was now tested using all 7400 cases of acute leukaemia reported to the Finnish Cancer Registry during the period 1964-2003, combining monthly cases to solar radiation and influenza epidemics.


The risk of acute leukaemia was greatest during the dark season when a significant proportion of Finns suffer vitamin D deficiency. The risk of acute myeloblastic leukaemia (AML) decreased by 58% per increase of 1000 kJ/m2/d in solar radiation. During influenza epidemics, AML increased by 9%, independently of radiation. As influenza epidemics usually occur in the vitamin D deficiency season, they may cause successive mutations and the latency period of leukaemia could therefore be short.

The study team included Timo Timonen (Oulu University Hospital, Department of Internal Medicine), Simo Näyhä (University of Oulu, Department of Public Health Science, and Finnish Institute of Occupational Health), Tapani Koskela (Finnish Meteorological Institute) and Eero Pukkala (Finnish Cancer Registry).

Further information: Dr. Timo Timonen (
Reference: Timonen T, Näyhä S, Koskela T, Pukkala E. Are sunlight deprivation and influenza epidemics associated with the onset of acute leukaemia? Haematologica 2007; 92: 1553-1556.