Lifestyle factors, obesity impact lymphoma risk

NEW YORK (Reuters Health) - Body size and patterns of smoking and drinking appear to modulate a person's risk of developing Hodgkin's and non-Hodgkin's lymphoma, a study shows.

Research conducted more than two decades ago estimated that "modifiable" lifestyle factors, like drinking, smoking and a Western diet, may account for two thirds of all cancers not related to genetics, the study team notes. "Subsequent studies have confirmed the estimate and added the contribution of obesity and physical inactivity," note Dr. Unhee Lim of the National Cancer Institute, Rockville, Maryland, and colleagues.

The researchers examined the association between lifestyle factors and lymphoma in 285,079 men and 188,905 women participating in the NIH-AARP Diet and Health Study.

During an average follow-up of 4.3 years, 43 men and 15 women were diagnosed with Hodgkin's lymphoma, and 958 men and 423 women were diagnosed with non-Hodgkin's lymphoma.

The risk of non-Hodgkin's lymphoma overall was lower by about 23 percent among those who consumed alcohol than among those who did not. Drinkers also had a lower risk of the main subtypes of non-Hodgkin's lymphoma.

Current smokers and those who had recently quit (less than 4 years prior) had a significantly higher risk of Hodgkin's lymphoma compared with never smokers.

On the other hand, the risk for non-Hodgkin's lymphoma overall and subtypes ... was not associated with smoking, except for a type called "follicular lymphoma," Lim and colleagues report. "We observed a lower risk of follicular lymphoma associated with both current and former smokers."

Morbid obesity -- defined as having a body mass index greater than 35 -- and being tall also raised the risk of non-Hodgkin's lymphoma.

Lim and colleagues say their results add to evidence that lifestyle factors are "modestly" associated with lymphoma risk, and the findings related to obesity warrant further investigation.

SOURCE: American Journal of Epidemiology, September 15, 2007.