TUESDAY, July 12, 2011 (HealthDay News) -- The immune systems of people with contact allergies may be primed to protect against certain types of cancer, including breast and brain cancers, new research suggests.
Contact allergies occur due to direct contact with chemicals and common metals such as nickel.
In the new study, researchers looked at almost 17,000 Danish adults who were tested for contact allergies between 1984 and 2008. About one-third (35 percent) tested positive for at least one contact allergy. Women were more likely than men to have a contact allergy -- 41 percent versus 26 percent.
When the study authors examined cancer cases among the participants over the long term, they found that men and women with contact allergies had significantly lower rates of breast and non-melanoma skin cancer, and women with contact allergies also had lower rates of brain cancer compared to those without contact allergies.
But people with contact allergies had higher rates of bladder cancer, which may be due to higher levels of chemical metabolites accumulated in the blood, the researchers suggested.
The study, by Kaare Engkilde of the National Allergy Research Centre at Copenhagen University, Gentoffe Hospital in Hellerup, Denmark, and colleagues, is published in the July 12 online edition of the journal BMJ Open.
The findings did not allow the researchers to come to any conclusions about cause and effect, and more study is needed, they noted in a journal news release. "However, if these relations are etiological, there are implications for understanding how contact allergy can affect cancer development and vice versa," Engkilde's team wrote in the report.
The Asthma and Allergy Foundation of America has more about allergies.