Cancer is caused as a result of environmental factors and genetic factors.
Cancer is mostly due to environmental carcinogens but genetic factors may also be the reason in certain cases.
The environmental factors like consumption of tobacco, poor diet, obesity, radiation, infection, lack of physical activity and environmental pollutants alter the genetic material of the cells.
Cell reproduction is a complex process, regulated by several classes of genes like oncogenes and tumor suppressor genes. Alteration in these regulator genes leads to the development of Cancer. These may be hereditary or acquired abnormalities. Few Cancers are mainly hereditary.
What are carcinogens that cause mutation of DNA?
Carcinogens are the agents which can induce the formation of Cancer. The agents may be physical, chemical or biologic agents and are capable of inducing Cancer. These agents can damage the cellular DNA, either directly or by producing toxic intermediates such as free radicals. Certain viruses also act as oncogens. These viruses induce mutations in the host cell DNA or they may alter the rates of cellular transcription. Mutations of cellular DNA leads to the formation of cells with abnormal growth and differentiation characteristics.
List of Carcinogens:
Chemicals – Many chemicals like vinyl chloride, benzene, cigarette smoke, aromatic hydrocarbons etc.,
Radiation, radon gas, radioactive materials, ultraviolet radiation
Occupational exposure to certain metals in the industries – Asbestos, coal dust, uranium, solvents
Oncogenic viruses
Dietary factors- high fat diet, excessive intake of alcohol, nitrosamine preservatives, grilled or charred foods
Hormones – estrogens, progesterone
Oncogenic viruses in humans
Both the DNA and RNA viruses are found to be oncogenic in nature, which are capable of producing Cancer in human hosts, they infect.
Human Papillomavirus cause cervical carcinoma
Hepatitis B virus cause liver Cancer
Epstein-Barr virus cause Burkitt’s lymphoma and nasopharyngeal Cancer
HIV virus cause Kaposi’s sarcoma
Hereditary factors:
Some Cancers like colon Cancer, breast Cancer, retinoblastoma, leukemia and lymphoma are predisposed genetically. The present research is focused to identify certain genetic markers in individuals that are basis for development of certain types of Cancer.