For cancer, besides the treatment method, the most important question that people are concerned about is: “Can cancer be prevented?” To answer this question, we must first answer how cancer occurs and whether it is hereditary. If our genome completely determines that we will/will not develop cancer, then there is no need to think too much about prevention. Where does cancer come from? We all know that cancer is a disease caused by malignant cell proliferation, so what are the causes of malignant cell proliferation? First of all, the cause of malignant cell proliferation is the mutation of DNA, mainly the mutation of some oncogenes (such as genes encoding cell cycle regulating proteins, DNA repair mechanism proteins, and inhibitors of cell growth signaling pathways), which is also the “internal” and starting factor of cancer, and is the cause of igniting the “fire” of cancer. Many of these DNA mutations are hereditary, the most famous being the BRCA1 gene mutation carried by Angelina Jolie, which causes breast and ovarian cancer. Of course, other factors can also lead to DNA mutations, such as ultraviolet radiation can lead to skin cancer; some toxic substances intake, such as benzo(pyrene) (present in substances produced after barbecue), dioxins (present in waste incineration exhaust), etc., they will be absorbed into human cells and inserted into the DNA base sequence to cause DNA mutations, while formaldehyde can directly damage DNA, which in turn will lead to lung cancer, etc. Therefore, avoiding the intake of these carcinogens is very important for cancer prevention. Chronic inflammation can cause cancer? Studies in the last decade have found that chronic inflammation is closely related to the development of cancer, and it is the “fuel” that promotes the burning of the “fire” of cancer, and it is the “exogenous factor” that induces the development of cancer. “Chronic inflammation can trigger the immune system. Chronic inflammation can induce the activation of immune cells and the release of immune cytokines, while the activation of the immune system, which seems to be able to inhibit tumor growth, becomes a breeding ground for cancer. The mechanism is that immune cell activation releases many growth factors that promote tumor cell growth; promotes the process of immune cells entering tissues from blood vessels but simultaneously promotes cancer growth and metastasis and induces angiogenesis; promotes blood vessel growth, thus promoting blood supply and growth of cancer tissues, etc. The tissue damage and repair caused by inflammation allows cells to proliferate, thus increasing the probability of mutation accumulation. Cancer prevention starts with lifestyle changes Chronic inflammation of various organs in the body is mainly caused by lifestyle. Of course, there are some differences in innate immunity of each individual, but it is not the main cause in the occurrence of chronic inflammation. So what are the bad lifestyles that can lead to chronic inflammation and thus cancer? Smoking (including second-hand smoke) Tobacco has a complex composition and contains many substances. After burning, it produces hundreds of organic substances, such as aldehydes, nitrogen oxides, benzopyrene, etc., which are very irritating to the mucous membrane of the respiratory tract and very toxic to the cells of the respiratory system. Asbestos, soot and other substances that can be deposited in the respiratory system to stimulate the respiratory system for a long time are also likely to cause cancer. Drinking alcohol becomes acetaldehyde after metabolism, which is very toxic to liver cells. Drinking too much alcohol leads to liver cell necrosis and alcoholic liver, which will further develop into cirrhosis and liver cancer. Eat too hot food: food with too high temperature can easily damage the mucous membrane of esophagus, and frequent eating of hot food can cause chronic inflammation of esophagus and induce esophageal cancer. Eating too fine: too fine diet and low fiber content will lead to slow excretion of intestinal contents, which will easily induce intestinal inflammation and lead to colon and rectal cancer, which is the main reason why the incidence of rectal cancer in western countries remains high. There is also a mantra that if you don’t eat dry, you don’t get sick. In fact, gastritis caused by unclean diet and irregular diet is one of the main reasons for the high incidence of gastric cancer in developing countries. Hepatitis caused by hepatitis B virus can lead to liver cancer, while cervical cancer is mainly caused by human papilloma virus (HPV) infection. To prevent cancer, we should start from removing the “fuel” and extinguishing the “fire”, maintain healthy living habits, and reduce the possibility of chronic inflammation in the body. We also need to maintain a good state of mind, do more physical exercise and strengthen our immune system so that even if there is a small amount of inflammation and a few cancerous cells in the body, they can be resolved quickly and will not develop and deteriorate in the long run.