NEW YORK (Reuters Health) - Sun exposure apparently has a protective effect against the development non-Hodgkin's lymphoma (NHL), a blood cancer, Australian researchers report.
Dr. Anne Kricker, of the University of Sydney, and colleagues investigated the possibility that high sun exposure is associated with an increased risk of NHL -- and found the opposite -- according the results of a study published in the International Journal of Cancer.
The team's population-based study involved adults between the ages of 20 and 74 years. In total, 704 cases of NHL and 694 randomly selected matched controls were enrolled.
The researchers used a questionnaire and a telephone interview to estimate details of typical sun exposure over as long as 6 decades. These took into account factors such as working, non-working and vacation days.
The risk of NHL decreased with increasing hours of sun exposure. With the highest exposes, the odds of having NHL decreased by 35 percent compared with the lowest exposure level.
One effect of sunlight is to stimulate the body's production of vitamin D. The researchers say that "increasing evidence that vitamin D may protect against cancer makes ultraviolet-mediated synthesis of vitamin D a plausible mechanism whereby sun exposure might protect against NHL."
SOURCE: International Journal of Cancer, December 10, 2004.