Why do people develop tumors?

Tumors are abnormal new growths formed by various carcinogenic factors. They are divided into benign and malignant. Malignant tumors are caused by the interaction between environmental factors and individual genetic material.

What are the environmental factors that contribute to tumor formation?

Human exposure to chemical, biological, and physical carcinogens that are widely present in the environment, or exposure to carcinogenic environments through various lifestyles and production activities, is causally related to tumor formation.

(1) Chemical factors: aflatoxin, nitrosamines, aromatic amines, benzene, aromatic amines, chromium, polycyclic aromatic hydrocarbons and chemotherapeutic drugs. Among them, aflatoxin can cause liver cancer; nitrosamines can cause esophageal cancer; vinyl chloride can cause hepatic angiosarcoma; aromatic amines can cause bladder cancer; and kerosene can cause squamous cell carcinoma.

(2) Biological factors: mainly viruses or other microorganisms. For example, Helicobacter pylori (HP) is associated with gastric cancer/gastric lymphoma; human papillomavirus (HPV) infection can cause cervical cancer and head and neck squamous cell carcinoma. Liver cancer is associated with hepatitis B/C virus (HBV/HCV); Epstein-Barr virus (EBV) infection can cause nasopharyngeal carcinoma and lymphoma; human herpes virus-8 (HHV-8) is associated with Kaposi's sarcoma; Schistosoma haematobium can cause bladder cancer; human T-cell leukemia virus-1 (HTLV-1) is associated with leukemia; liver fluke is associated with bile duct cancer.

(3) Physical factors: various ionizing radiations (X/γ rays, electrons, protons, α particles, heavy ions, etc.), ultraviolet rays, asbestos, etc. Ionizing radiation can cause tumors of the skin, lungs, breasts, bones, thyroid glands, leukemia, etc.; long-term exposure to ultraviolet rays can lead to skin tumors, such as basal cell carcinoma, squamous cell carcinoma of the skin, and malignant melanoma; long-term exposure to asbestos is associated with lung cancer and malignant mesothelioma. Among them, ionizing radiation can treat tumors, but it can also cause tumors. When it plays a role in treating tumors, it is necessary to consult a professional physician. You cannot ignore its anti-cancer effect due to its potential carcinogenic effect and miss the opportunity for treatment.

What are the personal genetic factors that contribute to tumor formation?

After exposure to carcinogens, some people develop tumors while others do not. This is related to individual genetics, that is, key gene mutations in the "cancer pathway."

(1) Tumor suppressor gene mutation: a gene that suppresses tumor formation, which loses its function of suppressing tumor formation after mutation. For example, Rb mutation is closely related to retinoblastoma; P53 mutation can cause Li-Fraumeni syndrome, various sarcomas, breast cancer, brain tumors, leukemia, lung cancer, prostate cancer and cervical cancer; APC mutation can induce familial adenomatous polyposis coli to form colon cancer.

(2) Proto-oncogenes: Genes that promote tumor formation. Mutations promote tumor formation. For example, K-Ras mutations are associated with lung cancer, colorectal cancer, and pancreatic cancer; EGFR mutations are associated with breast cancer, lung cancer, and gastric cancer; Myc mutations are associated with lymphoma, lung cancer, colon cancer, and leukemia; RET mutations are associated with medullary thyroid carcinoma and multiple endocrine neoplasia.

(3) DNA repair gene mutations: Genes that repair abnormal DNA. Defects or instability can promote tumor formation. For example, BRCA1 and BRCA2 mutations are hereditary factors for familial breast cancer. BRCA1 mutation carriers are also prone to ovarian cancer, while BRCA2 mutations are associated with male breast cancer and pancreatic cancer.

What other factors are related to tumorigenesis?

(1) Lifestyle: An unhealthy lifestyle increases the probability of developing a tumor. For example, smokers have a high incidence of lung cancer, and long-term alcoholics are more likely to develop liver cancer. A high-fat, high-calorie diet is associated with breast cancer and colorectal cancer. People who like hot or scalding foods have a high incidence of esophageal cancer. Long-term oral contraceptive use is associated with cervical cancer, breast cancer, and endometrial cancer.

(2) Other factors, such as age, gender, health, and economic conditions. As age increases, the risk of cancer increases, such as breast cancer, cervical cancer, and prostate cancer; thyroid cancer is more common in women; people with poor hygiene conditions have an increased risk of cervical cancer; and people with long-term malnutrition are associated with an increased risk of esophageal cancer. In addition, emotional instability such as pessimism, depression, irritability, anger, despair, and anxiety also play a role in tumor formation.

Are tumors contagious?

Infectious diseases need to meet three elements: source of infection, transmission route, and susceptible population. Tumors have genetic susceptibility. Therefore, tumors do not have the above three elements and are not infectious diseases, but genetic diseases.

In general, tumor formation is a multi-factor, multi-step, and multi-gene process. When discussing the causes of tumors, we cannot simply apply the results of a specific population to another different population. We must maintain a healthy and positive lifestyle and attitude to face life.