A term for diseases in which abnormal cells divide without control and can invade nearby tissues. Cancer cells can also spread to other parts of the body through the blood and lymph systems. There are several main types of cancer. Carcinoma is a cancer that begins in the skin or in tissues that line or cover internal organs. Sarcoma is a cancer that begins in bone, cartilage, fat, muscles, blood vessels, or other connective or supportive tissue.
Leukaemia is a cancer that starts in blood-forming tissue, such as the bone marrow, and causes large numbers of abnormal blood cells to be produced and enter the blood. Lymphoma and multiple myeloma are cancers that begin in the cells of the immune system. Central nervous system cancers are cancers that begin in the tissues of the brain and spinal cord. Also called malignancy.
There is uncontrolled cellular proliferation. There is ability to metastaze/ migrate from the original site and spread to distant sites throughout the body.
Causes of cancer which are exogenous:
Tobacco use. There is ample evidence suggesting tobacco in various forms, including smoking, chewing and betel quid etc., have carcinogenic impact in the oral cavity. The commonest form of tobacco use is smoking. The various forms in which tobacco is used as smoke are- cigarettes, cigars, pipe and bidi etc hookah or chillum (it's a clay pipe used to keep the burning tobacco) are other common forms of smoking in some countries of Asia including India. In some parts of India like Mizoram, tobacco smoke is dissolved in water (“smoke on the water”) which is another peculiar form of tobacco use. Cigarette smoke contains at least 80 known mutagenic carcinogens, including arsenic, cadmium, ammonia, formaldehyde, and benzopyrene. Each will have a separate mechanism for causing cancer. It is also a source of oxidative stress. Compared with non- smokers, active smokers have lower circulating concentrations of several antioxidant micronutrients including alpha-carotene, beta carotene, cryptoxanthin, and ascorbic acid.
Alcohol. Numerous studies have suggested alcohol to be a major risk factor for oral cancer (OC). There is a certain degree of controversy whether alcohol alone may have carcinogenic impact. This is due to simultaneous tobacco and alcohol intake of study subjects in various epidemiological studies. Studies have shown that individuals consuming more than 170g of whiskey daily have ten times higher risk of OC than the light drinkers. Alcohol may have additive effects and it has been suggested that it facilitates the entry of carcinogens into the exposed cells, altering the metabolism of oral mucosal cells. However, the current evidence does not suggest that pure ethanol alone is a carcinogen for the development of OC.
Infectious agents (e.g. Bacteria, parasites, Viruses). Infectious agents, including viruses,bacteria, and parasites, can induce DNA damage and promote cancer development. Some infectious agents, including hepatitis viruses, the bacterium Helicobacter pylori (H pylori ) and parasites, also promote cancer by causing chronic inflammation. Both DNA and RNA viruses can cause cancer, although the mechanisms differ. DNA viruses encode viral proteins that block tumour suppressor genes, whereas RNA viruses or retroviruses encode oncogenes.
Medications. A number of medical treatments modify the risk of some cancers. X- rays are carcinogenic, as is radiation used as cancer treatment. Another example has been diethylstilboestrol, once prescribed in pregnancy and now withdrawn, which caused cancers of the vagina and cervix of female children born to mothers who received this drug. Chemotherapy as cancer treatment during childhood is followed by an increased risk of lymphoma in adulthood.
Radiation. Both ionising radiation and UV radiation damage DNA and act as carcinogens. This includes radiation used in X- ray radiographs and in the treatment of cancer. Ionising radiation can cause DNA damage, both directly by causing breaks in the DNA strands, and indirectly by interacting with water molecules and generating reactive oxygen species that damage DNA. Although sunlight causes DNA damage, it also induces production of vitamin D.
Chemical exposure (e.g, polychlorinated biphenyls, organic compounds used in plastics, paints, adhesives). Certain industrial chemicals and pesticides persist in the environment and become concentrated in the food chain. Polychlorinated biphenyls (PCBs), organic compounds previously used in plasticisers, adhesives, paints and various oils, do not readily degrade. They are soluble in fat rather than water and thus accumulate in carnivorous fish such as fish. They also accumulate in human milk, and can be passed to the infant during breastfeeding. There is limited experimental evidence suggesting that PCBs have sex.
Carcinogenic components found in food and beverages(e.g, aflatoxins, heterocyclic amines, polycyclic, aromatics, hydrocarbons, n-nitroso compounds). Food may be contaminated with natural or man-made carcinogenic toxicants, aflatoxin B, a product of the Aspergillus fungus and a common contaminant of cereals and peanuts, is an established cause of liver cancer. Fumonisin B, a toxin produced by the fungus Fusarium verticillioides, may be found on maize and may be carcinogenic, although epidemiological studies are lacking.
This article is written and submitted to The E Today by Shrushti Mehta.
We thank her for her research and analysis and hope to see the awarenesses about health and nutrition being spread ahead to larger mass of our citizens.