A new article in the December issue of The Quarterly Review of Biology provides strong evidence that allergies are much more than just an annoying immune malfunction. They may protect against certain types of cancer.
The article, by researchers Paul Sherman, Erica Holland and Janet Shellman Sherman from Cornell University, suggests that allergy symptoms may protect against cancer by expelling foreign particles, some of which may be carcinogenic or carry absorbed carcinogens, from the organs most likely to come in with contact them. In addition, allergies may serve as early warning devices that let people know when there are substances in the air that should be avoided.
Medical researchers have long suspected an association between allergies and cancer, but extensive study on the subject has yielded mixed, and often contradictory, results. Many studies have found inverse associations between the two, meaning cancer patients tended to have fewer allergies in their medical history. Other studies have found positive associations, and still others found no association at all.
In an attempt to explain these contradictions, the Cornell team reexamined nearly 650 previous studies from the past five decades. They found that inverse allergy-cancer associations are far more common with cancers of organ systems that come in direct contact with matter from the external environmentthe mouth and throat, colon and rectum, skin, cervix, pancreas and glial brain cells. Likewise, only allergies associated with tissues that are directly exposed to environmental assaultseczema, hives, hay fever and animal and food allergieshad inverse relationships to cancers.
Such inverse associations were found to be far less likely for cancers of more isolated tissues like the breast, meningeal brain cells and prostate, as well as for myeloma, non-Hodgkins lymphoma and myelocytic leukemia.
The relationship between asthma and lung cancer, how
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