Allergy sufferers are much less likely to get some types of cancers. Theories regarding allergy - cancer link are mixed.
Many say it is due to hyper-sensitive immune response. But the correlation between allergy and lowered glioma risk is also difficult to explain, due to blood -brain barrier.
However there was one interesting theory, saying that, allergy is an evolutionary anti-cancer protection. Allergy sufferers simply do not let some of the carcinogens to come into their body.
I am computer engineer. When we setup a protection at a system (antispam, antivirus, firewall) there is sensitivity level that we have to select. Higher sensitivity offers better protection but also results in more false positives. However not all false positives are due to higher sensitivity. Some can simply be due to faulty protection system.
So my question is, can allergy or auto-immune diseases be sign of high-sensitive immune system which will have advantages and disadvantages or just a sign of simply faulty immune system which will have only disadvantages?