Allergies and allergy-related conditions are not likely related to non-Hodgkin lymphoma risk, according to a new study. Some previous studies had suggested that allergies might protect against this cancer.
The body’s allergic reaction to a substance includes an increase in specific types of immune cells. Some researchers have observed a possible association between allergies and reduced cancer risk and suggested that the allergy-induced immune response also might inhibit tumor growth. Non-Hodgkin lymphoma, a cancer of the immune system, is particularly sensitive to immune system changes, and earlier studies reported a decreased risk of this cancer among people with allergic rhinitis, hay fever, or food allergies. However, several other studies found no such association.Mads Melbye, M.D., Ph.D., of the Statens Serum Institut in Copenhagen, and colleagues decided to investigate the relationship more thoroughly. First they looked at a retrospective study of 3,055 patients with non-Hodgkin lymphoma and 3,187 control patients without the disease. Questionnaire data and blood samples were collected after people were diagnosed with non-Hodgkin lymphoma.Initially they found that people who had ever had hay fever had a reduced risk of non-Hodgkin lymphoma. Specifically, people with high levels of the antibodies specific for hay fever had a 32 percent lower risk of NHL than people who didn’t have hay fever. However, further investigation revealed that among patients with cancer, the more the cancer had spread throughout the body, the lower the antibody levels were. This suggested to the researchers that allergic responses might be dampened by having non-Hodgkin lymphoma.”Our finding of a lower prevalence of allergic rhinitis among case patients with non-Hodgkin lymphoma than among population control subjects may reflect a recent decline in clinical manifestations of allergic conditions as a result of underlying non-Hodgkin lymphoma disease,” the authors write.The authors then studied the association in a prospective case-control population; blood samples were available for 198 lymphoma patients before they developed their cancer and for 594 control patients. When they looked at antibody levels in people before they developed cancer, they found that there was no association between allergy and the development of non-Hodgkin lymphoma.”Allergy may not be causally associated with the risk of non-Hodgkin lymphoma. The inverse association observed in some case-control studies may arise because non-Hodgkin lymphoma suppresses the immunologic response to allergens,” the authors write.(Source: Journal of the National Cancer Institute : Statens Serum Institut : January 2007.)