July 13th, 2011

Time Healthland reports:

Certain environmental exposures are known to increase your risk of cancer: tobacco smoke, UV radiation and even pollution. But what about some common metals and chemicals that cause contact allergies?

Curiously, according to the latest research from scientists in Denmark, these environmental allergens may actually help protect some people from developing cancer. After studying more than 17,000 adults who were tested for common contact allergies — for instance, to nickel and other chemicals — lead author Kaare Engkilde of the National Allergy Research Center at Copenhagen University Hospital Gentofte concluded that those who tested positive for such allergies were less likely to develop cancer years later than those who did not have contact allergies.

Engkilde’s team matched up the allergy test results, which were collected in a database from 1984 to 2008, with Denmark’s national cancer registry, which has recorded all cases of diagnosed cancer among citizens since 1943. For some of the participants, therefore, the study follow-up stretched to nearly three decades.

About a third of people tested positive for contact allergies, which means they developed a rash or swelling when researchers exposed a patch of their skin to an allergen. A smaller proportion, nearly 20% of all of the people tested, went on to develop some type of growth, either malignant or benign; of these, about 38% had tested positive for allergy.

The researchers found that having a contact allergy was associated with a strong protective effect against cancer: those who tested positive for allergies were less likely to develop cancer in later years than those who didn’t have allergies. The relationship was strongest for breast and skin cancers that weren’t due to melanoma.

For the rest of the story, go to Time Healthland