One good thing about having Asthma or hay fever, if such a thing can be said, is that it apparently reduces the overall risk of dying of cancer, compared with the odds for people with neither of these allergic conditions, according to a new report.
Previous studies have suggested this pattern, the authors explain in the American Journal of Epidemiology, but some reports have shown an increased risk of lung cancer in asthma patients.
Dr. Michelle C. Turner from the University of Ottawa, Ontario, Canada and associates used data from the American Cancer Society Cancer Prevention Study II to examine the association between allergy and cancer risk.
Participants with histories of both Asthma and hay fever were 12 percent less likely to die from cancer, the researchers found. For those with hay fever only the chances were reduced by 8 percent, and among those with asthma and/or hay fever the reduction in risk was 6 percent.
A history of asthma only was associated with a lower risk of death due to leukemia but a higher risk of dying of lung cancer, the report indicates. A history of hay fever only was associated with a significantly lower risk of pancreatic cancer mortality.
The cause is unknown, but it is more common in smokers and in obese individuals. Almost 1/3 of cases of pancreatic carcinoma can be attributed to cigarette smoking. There is controversy as to whether type 2 diabetes is a risk factor for pancreatic cancer. A minority of cases are known to be related to hereditary syndromes.
“Collectively, these results suggest an association between a history of allergy and cancer mortality,” the authors conclude. “However, the strength of the evidence for this association is limited.”
Turner said: “Additional large prospective studies with better allergy indicators and cancer incidence, as well as laboratory studies examining potential biological mechanisms for a potential association, would be useful.”
SOURCE: American Journal of Epidemiology, August 2005.
Revision date: June 14, 2011
Last revised: by Jorge P. Ribeiro, MD