Clinical contact with many tumor patients will ask, “Why do I have cancer? What is the cause of cancer?” There are many such questions, what are the causes of cancer? Let’s talk about it together.
The etiology of malignant tumors is not fully understood. It is believed that the occurrence of tumor is a gradual process caused by the combination of endogenous (our genetic, immune and endocrine) and exogenous (chemical, physical and biological) factors.
Endogenous factors
1. Genetic factors: The real tumors directly inherited are only a few uncommon tumors. The role of genetic factors in the occurrence of most tumors is to increase the body’s propensity to develop tumors and susceptibility to carcinogenic factors, such as colon polyposis, breast cancer, stomach cancer, etc. The above mentioned Hollywood star Angelina? Jolie is a BRCA1 gene mutant.
Immune factors: congenital or acquired immune deficiencies are prone to malignant tumors, such as leukemia and lymphopoietic system tumors in patients with gammoprotein deficiency, and tumor incidence is higher in patients with long-term application of immunosuppressive drugs after kidney transplantation, but most malignant tumors occur in people with “normal” immune function, mainly because The main reason is that the tumor can escape from the surveillance of immune system and destroy the immune system of the body, the mechanism is not completely clear.
3. Endocrine factors: estrogen and prolactin are related to breast cancer, and growth hormone can stimulate the development of cancer.
External factors
1.Chemical factors.
①Tobacco, 600,000 new lung cancer patients worldwide every year, 85% for men and 75% for women, caused by smoking; 98% of lung cancer patients have smoked, and the risk of lung cancer for smokers is 20 times higher than that for non-smokers; in addition, smoking can cause lip cancer, oral cancer, larynx cancer and many other tumors.
② thermal cleavage products produced in food cooking, which is widely found in fried and baked animal proteins. It is prone to induce bladder cancer and liver cancer.
③Carcinogenic drugs, such as azathioprine, methylcyclohexylnitrosourea, cyclophosphamide, thiotepa, etc.
(iv) Thick cyclic aromatic hydrocarbons, such as coal tar, heavy oil, coal tar pitch, petroleum pitch, wood distillate and other contact history can lead to skin.
⑤ fungal toxins and plant toxins, such as aflatoxin easily contaminated food, can cause liver cancer, kidney cancer, adenocarcinoma of the stomach and colon; thapsigargin, safrole and fern toxins can also cause liver cancer.
(6) Occupational carcinogens, such as alkylating agents, benzene preparations, arsenic preparations and some metal manufacturing industries, etc.
2.Physical factors.
①Ionizing radiation, such as skin cancer and leukemia caused by improper X-ray protection, once became an occupational disease of radiation workers; in addition, inhaling radioactive contaminated dust can cause osteosarcoma and thyroid tumor, etc., which is also one of the causes of medical carcinogenesis
② ultraviolet light, can cause skin cancer, especially for susceptible individuals (patients with pigmented dry skin disease) is obvious.
③Other factors, such as deep scar of burns which is prone to carcinogenesis in the long term, chronic skin ulcers which may cause squamous skin cancer, and asbestos fiber which is related to lung cancer, may be caused by local physical stimulation.
3.Biological factors: mainly viruses. For example, EB virus is related to nasopharyngeal cancer and Burkitt’s lymphoma, herpes simplex virus is related to cervical cancer, hepatitis B virus is related to liver cancer, and C-type RNA virus is related to leukemia and Hodgkin’s disease. In addition, such as Helicobacter pylori infection is related to the occurrence of gastric cancer; Schistosoma egypti can cause bladder cancer, Schistosoma waxeri is related to liver cancer, and Schistosoma japonicum can cause colorectal cancer.
The etiology of tumor is diverse, and the formation of tumor may be the result of the joint action of multiple factors. If we face up to the causes of tumor formation, change the bad life style and protect the environment, tumor is actually not terrible.