Allergies and hyperreactive immune system might eliminate abnormal cells more efficiently, thus lowering cancer risk

Epidemiologic evidence regarding the association between allergic diseases and cancer has been inconsistent.

This Canadian study examined whether a history of asthma or eczema is associated with various cancers among men in a population based case-control study conducted in the 1980s. Questionnaire-based interviews were performed in 3,300 cancer cases and 512 population controls

A history of asthma was negatively associated with all cancer types combined (odds ratio (OR), 0.72) and similarly for a history of eczema (OR, 0.66).

Although ORs between asthma and eczema and most individual cancer types were below 1.0, only 2 ORs were significantly below 1.0: that between asthma and stomach cancer (OR, 0.27) and that between eczema and lung cancer (OR, 0.34).

Allergic conditions that result from a hyperreactive immune system might lead to a more efficient elimination of abnormal cells, thus lowering cancer risks.

References:

History of asthma or eczema and cancer risk among men: a population-based case-control study in Montreal, Quebec, Canada. El-Zein M, Parent ME, Kâ K, Siemiatycki J, St-Pierre Y, Rousseau MC. Ann Allergy Asthma Immunol. 2010 May;104(5):378-84.
Relationship between Allergy and Cancer: enhanced immunosurveillance might prevent cancer http://goo.gl/uq9mC
The nascent field of AllergoOncology  http://goo.gl/tUZ32
Image source: Cancers are caused by a series of mutations. Wikipedia, public domain.

Comments from Twitter:

@lrlee: Guess I'll never get cancer then - Allergies may lower cancer risk http://goo.gl/JIv7