Is it true that allergies protect against cancer?

There is a widespread belief on the Internet that allergic reactions prevent the development of cancer. We decided to check how substantiated such statements are.

Many media outlets report that people suffering from allergies are less susceptible to cancer than others (for example, “Arguments and facts", "Russian newspaper", Lenta.ru And "Channel 5») And news portals. This information can be found on nearby medical websites And resources about a healthy lifestyle, on social networks (“VKontakte", X) and on blogging platforms (LiveJournal, "Zen").

Immunity - one of the body’s defense systems, it is designed to fight aggressive environmental factors, such as bacteria and viruses. But sometimes the immune system “sees” aggressors (that is, allergens) in harmless foods, animal hair, plant pollen, etc. Inappropriate excess reaction the immune system to substances that do not themselves harm the body and, accordingly, should not cause such a response, is called an allergy. Depending on which organs or tissues come into contact with allergens, the symptoms also differ: the skin may begin to itch and peel, the upper respiratory tract “responds” with sneezing and a runny nose, and the digestive system with abdominal pain and nausea. All these reactions are aimed at quickly getting rid of irritants and removing them from the body - for example, with mucus or dead skin flakes.

The immune system “monitors” not only external stimuli, but also the internal state of the body. Healthy cells The human body goes through a cycle of growth, division and death. But if the DNA of a cell mutates for one reason or another, the cell may stop following this cycle: begin to divide too quickly and uncontrollably, not die when its function is completed, etc. Such cells are called cancer cells. Immune system capable recognize them and destroy them, but in some cases this cannot be done, and then a person may develop cancer. One of the methods of treating cancer is just immunotherapy, when immune system cells are specifically stimulated to attack tumors.

Mutations in DNA can bring both genetic and acquired factors - exposure to radiation and carcinogenic substances, bad habits (for example, smoking or excessive alcohol consumption), viruses, chronic inflammation, etc. Allergic reactions aimed at removing substances that are dangerous from the point of view of the immune system from the body can indirectly contribute to the removal of carcinogens. Study, conducted in 2008 by scientists from Cornell University (USA), confirms that allergy sufferers were less likely to develop cancer of organs that interacted with environmental factors (for example, food or air) and responded to them with allergic reactions. Scientists studied more than 600 scientific papers published over half a century. A negative correlation was found between the presence of allergies and the incidence of cancer of the colon, skin, bladder, mouth, throat, uterus and cervix, lungs, and gastrointestinal tract. In this case, for example, asthma, which has similar symptoms to allergies, on the contrary, is associated with an increased risk of lung cancer - unlike allergies, it does not provoke the secretion of mucus and, as a result, the removal of foreign particles, but delays it.

Researchers came to a similar conclusion in 2019 analyzed Allergy and cancer data for nearly 2 million older Americans. Allergic rhinitis was found to be associated with lower rates of hypopharyngeal cancer, esophageal squamous cell cancer, cervical cancer, tonsil cancer, and vulvar cancer. More modest but significant inverse associations were noted for cancer of the esophagus (adenocarcinoma), stomach, colon and rectum, liver, gallbladder, lung, uterus, bladder and other organs. Those with asthma had a lower risk of developing liver cancer, while those with eczema were more likely to develop lymphoma.

Apparently, the role of allergies in the fight against cancer is not limited to the removal of potential carcinogens from the body. In 2011, a group of scientists from Denmark studied data collected from 1984 to 2008 on contact dermatitis (a type of allergic skin reaction to direct contact with chemicals) and cancer diagnosed in 17,000 patients. It turned out that among those who suffered from allergies, the incidence of non-melanoma skin cancer and breast cancer was significantly lower than that of their non-allergic counterparts. Also, some negative correlation was observed for brain cancer, but the researchers did not find it statistically significant. They argue that this relationship is due to the hypersensitivity of the immune system, which leads to allergies, and also allows the body to identify mutated cells in the early stages and immediately destroy them.

In 2022, scientists from the Luxembourg Institute of Health published results an experiment in which glioblastoma cells (one of the most aggressive and difficult to treat types of cancer) were implanted into the brains of mice, and then allergic reactions were stimulated in one of the groups of animals. As a result, in this group, the allergy caused the immune cells of the brain to become inflamed, and they more actively and effectively resisted the development of tumors. The survival rate of these animals was significantly higher than that of mice without allergies (their glioblastoma developed faster and more aggressively). Scientists note that the mechanisms of this effect of allergic reactions on the fight against cancer have yet to be studied in detail, but certain patterns are already visible.

However, allergies are inflammation in the body, and chronic inflammation can become one of the causes of gene mutations and, as a result, the development of cancer. Despite the fact that available statistics allow caution to speak about an inverse relationship between allergies and the risk of developing certain types of cancer, experts note that a balance is necessary in allergy-oncology. After all, what can serve as a means of prevention and treatment can simultaneously lead to the development of the disease.

Thus, current research indeed suggests that allergy sufferers are less likely to suffer from certain types of cancer. This appears to be due to the hypersensitivity of the immune system, which is more effective at detecting defective cells, as well as the physical symptoms of allergies, which remove potential carcinogens from the body. However, the mechanisms of the influence of allergies on cancer and precancerous conditions have not yet been fully studied - the relationship has not been found with all types of malignant tumors, research is ongoing. In addition, most of such studies are correlational, that is, identifying patterns, but not cause-and-effect relationships. It is quite possible that the studies did not take into account any other factors that also influence the development of cancer. In addition, there is reason to believe that allergic reactions that lead to chronic inflammation can themselves cause cancer.

Cover photo: pexels.com

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Read on the topic:

1. NHS. Cancer vs the immune system
2. Myths and misconceptions about allergies
3. Is it true that dandelion tea is a proven effective cancer treatment?