There definitely has been an increase in allergens in the world - more toxic chemicals are used more widely than ever before - and more people are showing up allergic. Basically for allergies, we are always told avoidance is the best policy and new chemicals (drugs) are developed to ease the symptoms.
But what if the allergies interfere with the best possible treatment for cancer or another condition? I was told as a child that I was sensitive to penicillin. By sheer luck, I did not receive any for years until in my late 30's, I got a dental infection and was prescribed amoxicillin which resulted in a full body rash and hives (while on a business trip overseas - how fun. NOT!)
Later while in chemo, I discovered an allergy to benadryl (yes the stuff they give you for allergic reactions). During chemo, the protocol is to give you some combination of an anti nausea drug, a steroid to reduce reactions, and sometimes an anti-allergy medication (Benadryl in this case) to reduce reactions to the very strong chemo drugs. Well, I had a reaction for about 30 minutes and was told never to take Benadryl again. But I was not allergic to any of the chemo drugs.
But what if a patient is allergic to the best possible treatment for their illness? What then? Do you suffer through the allergic reactions (and hope you are okay) or do you go to a potentially less effective treatment? Well the new theory is densensitization of patients to drugs so they can get the best possible treatments.
Through my cancer treatment, I always wanted the option with the best possible numbers associated with it. If I was allergic to one of the drugs, I think I would want to try this new option to have the best possible odds. Consider it the same as driving an extra hour to get to the best hospital. Why not?