Why does chronic inflammation cause cancer?
Compared with acute inflammation, chronic inflammation often doesn't cause such intense sensations, but it is closely related to cancer, including some of the most common types.
For example, lung cancer is associated with chronic inflammation of the lungs; liver cancer is related to chronic hepatitis; esophageal cancer is linked to esophageal inflammation; gastric cancer is associated with chronic gastritis; and so on.
Below is a table I've compiled, showing common cancers, their associated chronic inflammations, and the main inducing factors.
| Cancer Type | Associated Damage and Chronic Inflammation |
|---|---|
| Gastric cancer | Chronic gastritis caused by Helicobacter pylori infection |
| Liver cancer | Chronic hepatitis caused by hepatitis B/C virus infection |
| Cervical cancer | Long - term infection with human papillomavirus (HPV) |
| Colorectal cancer | Chronic inflammatory bowel disease (such as ulcerative colitis, Crohn's disease) |
| Esophageal cancer | Chronic esophageal inflammation caused by consuming overly hot food and drinks, acid reflux, etc. |
| Lung cancer | Chronic pneumonia caused by smoking, air pollution, kitchen fumes, etc. |
| Pancreatic cancer | Chronic pancreatitis caused by smoking/drinking, autoimmune diseases, etc. |
| Bladder cancer | Chronic cystitis, chronic urinary tract infection |
| Nasopharyngeal cancer | EBV virus infection and chronic inflammation of the nasopharynx |
| Head and neck cancer | Chronic inflammation caused by smoking/drinking, HPV infection, etc. |
| Breast cancer | Systemic chronic inflammation and hormonal imbalance caused by obesity |
As you can see, some inflammations are related to infections and can be prevented and treated. For example, there is a vaccine for the hepatitis B virus, and the hepatitis C virus and Helicobacter pylori can be cured with medication.
Some inflammations are related to lifestyle and can be noted and avoided, such as smoking, drinking, consuming overly hot food, and also the endocrine disorders and systemic inflammation caused by obesity.
Some are mainly related to innate genes, such as pancreatitis and enteritis associated with autoimmune diseases. Currently, these are difficult to cure, but we can try our best to control the symptoms and reduce the degree and harm of inflammation.
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Why does chronic inflammation increase the risk of cancer?
It's quite complicated. After decades of scientific research, at least five crucial mechanisms have been discovered.
The first is DNA damage. Chronic inflammation produces compounds such as reactive oxygen species and reactive nitrogen species in cells, which can directly damage the DNA of cells. If these damages are not repaired in time, they will cause gene mutations over the long term, increasing the risk of carcinogenesis.
The second is stimulating cell growth. Inflammation is accompanied by the massive release of cytokines and growth factors. These signaling molecules can promote cell survival and division, and each cell division brings random DNA changes, increasing the probability of carcinogenic gene mutations over the long term. If cancer cells have already emerged, inflammation will also stimulate their growth.
The third is immune dysregulation. Chronic inflammation breaks the immune balance and distorts the normal function of the immune system, including weakening the ability to clear mutant cells. In chronic inflammation, cells may secrete immune - suppressing factors, reducing the activity of important immune cells such as killer T cells and helping cancer cells evade the attack of the immune system.
The fourth is promoting angiogenesis. Chronic inflammation can produce factors such as VEGF (vascular endothelial growth factor) that can promote the formation of new blood vessels. New blood vessels can provide essential nutrients and oxygen to tumors, promoting their growth and metastasis.
The fifth is the change in the tumor microenvironment. Chronic inflammation is accompanied by continuous tissue damage and repair. The repeated repair process will lead to changes in the cell microenvironment, such as fibrosis. Fibrosis may be conducive to the growth and spread of tumor cells.
The above reasons are not ranked in any order. If cancer occurs, it is most likely the result of their combined action.
In conclusion, chronic inflammation is definitely bad for the body. Everyone should pay attention to the relevant risk factors, avoid them if possible, and seek treatment if possible.
Having said all this, there's no need for everyone to panic.
The association between chronic inflammation and cancer only means that people with long - term inflammation have a slightly higher overall risk. It doesn't mean that having inflammation will definitely lead to cancer, let alone death from cancer.
In fact, everyone has some degree of chronic inflammation, and the difference lies only in the severity or whether it has been detected.
Everyone should, based on their own risks, pay attention to reducing the stimulating factors for the organs with more inflammation and then conduct corresponding screenings for those organs: low - dose CT for the lungs, gastroscopy for the esophagus and stomach, colonoscopy for the intestines, abdominal ultrasound + alpha - fetoprotein for the liver, etc. As long as cancer is detected early, it is not a terminal illness.
I wish everyone a happy mood and less interference from inflammation!
Salute to life!
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3.Inflammation-induced cancer: crosstalk between tumours， immune cells and microorganisms. Nature Reviews Immunology (2010)，10(11): 735-744
4.Inflammation and cancer: paradoxical roles in tumorigenesis and implications in immunotherapies. Genes Dis. 2021 Oct 18;10(1):151–164.