What is cancer?
In accordance with the normal physiological process, the cells grow and multiply. They form new cells which after a certain period of time attain the aging process and die. Due to the break in the normal etiological process by the cancerous agents, the damaged, deranged cells outgrow in excess of the limit and form tumour. It can be benign tumour or malignant tumour. When the cancerous cells invade the nearby cells or tissues or distant organs it is called as malignant tumours. Invasion of distant tissues is called as metastasis. In benign tumours, the excess newly formed cells are confined to their own borders.
How cancerous cells are different from normal cells?
Normal cells grow with signal transduction, divide normally and die. But cancerous cells grow irrespective of the signal transduction, grow abnormally and don’t follow the physiological death process or programmed cell death process known as apoptosis. Cancerous cells conceal from the immune mechanism and bring certain changes to our chromosomes.
Etiology–
1. Genetic — The most predominant cause of carcinogenesis is genetic. Genes carry instructions for formation of proteins whish are the building blocks of the cells. Any alteration of the genetic makeup can lead to abnormal growth and differentiation of tissues. This eventually land up in cancerous growth of tissues and metastasis. The notorious genes responsible for carcinoma are transferred from parents to the offspring. For example- breast carcinoma, colon cancers, leukaemia, lymphoma all have some genetic basis.
2. UV radiation- Ultraviolet radiation damage the cellular component producing reactive oxygen species(ROS). Reactive oxygen species are the molecules generated during the oxidation process like peroxides, hydroxyl ions, singlet oxygen. Most of the skin cancers like basal cell cancers, squamous cell carcinoma are the result of excess of UV rays exposure.
3. Tobacco smoke– It is another notorious substance containing so many potential carcinogens. Cancers related to the tobacco smoke are oral cancer, laryngeal, oesophagus, bladder cancer.
4. Infections– Longstanding Hepatitis b virus can cause hepatocellular carcinoma. Human papilloma virus infections are involved in cervical cancers. Epstein bar virus infection is associated with nasopharyngeal carcinoma. Human herpes virus-8 is linked with development of kaposi sarcoma.
5. Radiation– Radiation exposure damages the normal cells and it may propagate to form cancerous cells. The radiation exposure mostly seen in CT scan, X- rays, Gamma rays exposure. Various leukaemia, lymphoma are seen due to radiation exposure.
6. Chemicals– Certain chemicals like benzene, arsenic, asbestos, benzidine are potential carcinogens. These chemicals cause change in normal genes that alter the cellular transformation and differentiation leading to formation of cancers.
Antioxidants role in cancer
The development of cancer process is due to the oxidative stress by the potential harmful carcinogens described as above. They generate free radicals and reactive oxygen species. The free radicals damage the cellular component like proteins, DNA, cell membrane. The damage caused by these free radicals propagates to abnormal proliferation of cells or tumour cells formation. The role of the antioxidants is to put a break in abnormal tumour formation.
1. Vitamin A– It is responsible for the epithelial integrity. The epithelial damage caused by the free radicals produced by the carcinogens is repaired by vitamin A. The animal sources are cheese, eggs, fish, milk. The plant sources are mango, carrot, spinach, lettuce, tomato, sweet potatoes. The plant sources are called also beta carotene. Retinoids are demonstrated to inhibit the growth and development of many cancers like skin, breast, oral cavity, lung, bladder cancers.
Ralhan R study shows the retinoids act as chemo preventive agents useful in cancers due to their ability to regulate the cellular development, differentiation, homeostasis and regeneration.
Hansen LA study shows retinoids are effective chemo preventive agents against skin, head, breast, liver cancers. Differentiation therapy of acute promyelocytic leukemia is based on the fact that the ability of retinoic acid to induce differentiation of leukemic promyelocytes.
GT Budd study showed all trans-retinoic acid( ATRA) has anti-tumour effects in advanced breast cancer. All-trans retinoic acid is one of the isomer of vitamin-A.
2. Vitamin C– It is a water soluble vitamin having diverse roles in prevention of common cold to cancer. It helps in collagen formation. Natural vitamin C can prevent development of lung, breast cancers. Foods rich in vitamin C are orange, guava, tomato, broccoli, brussels sprout.
Cameron E study shows high dose of vitamin C is helpful in orthomolecular treatment of human cancers.
3. Vitamin E– It is a very potent anti-oxidant. The sources are sunflower, safflower, soyabean oils, peanut, rice bran oil, pumpkin, almonds. The active form is called as tocoferols.
Albanes D study shows alpha-tocoferols are helpful in prevention of lung cancers.
Hong Jin Lee study shows tocopherols prevent mammary tumorigenesis by inhibiting the action of estrogen.
