About Cancer

Cancer is a class of diseases characterized by an abnormal cell growth there are over 200 different types of cancer, and each is classified on the type of cell that affects initially. Cancer harms the body when damaged cells divide uncontrollably to form lumps or masses of tissue called tumors. Except in the case of leukemia where cancer prohibits normal blood function by abnormal cell division in the blood stream. Tumors can grow and interfere the digestive, nervous, and circulatory systems, and they can release hormones that alter body function. Tumors that stay in one spot and demonstrate limited growth are generally considered to be benign.

Formation of Malignant tumors:

1. A cancerous cell manages to move throughout the body using the blood or lymph systems, destroying healthy tissue in a process called invasion

2. That cell manages to divide and grow, making new blood vessels to   feed itself in a process called angiogenesis     

Cancer is ultimately the result of cells that uncontrollably grow and do not die. Normal cells in the body follow an orderly path of growth, division, and death. Programmed cell death is called apoptosis, and when this process breaks down, cancer begins to form. Unlike regular cells, cancer cells do not experience programmatic death and instead continue to grow and divide. This leads to a mass of abnormal cells that grows out of control.

When a tumor successfully spreads to other parts of the body and grows, invading and destroying other healthy tissues, it is said to have metastasized Certain molecular interactions between cells and the scaffolding that holds them in place (extra cellular matrix) cause them to become unstuck at the original tumor site, they become dislodged, move on and then reattach themselves at a new site.

It is nearly impossible to prove what caused a cancer in any individual, because most cancers have multiple possible causes.

1. Chemicals: Alcohol, the link between tobacco use and cancer in the lung, larynx, head, neck, stomach, bladder, kidney, esophagus and pancreas.] Tobacco smoke contains over fifty known carcinogens, including nitrosamines and polycyclic aromatic hydrocarbons Lung cancer and mesothelioma from inhaling asbestos fibers and tobacco smoke, or leukemia from exposure to benzene at their workplaces.
2. Diet and exercise: Diet, physical inactivity, and obesity are related to approximately 30 to 35% of cancer deaths. Diets that are low in vegetables, fruits and whole grains, and high in processed or red meats are linked with a number of cancers. A high salt diet is linked to gastric cancer, aflatoxin B1, a frequent food contaminate, with liver cancer, and Betel nut chewing with oral cancer.
3. Infection: Oncovirus Human papillomavirus (cervical carcinoma), Epstein-Barr virus (B-cell lymphoproliferative disease and nasopharyngeal carcinoma), Kaposi's sarcoma herpesvirus (Kaposi's Sarcoma and primary effusion lymphomas), hepatitis B and hepatitis C viruses (hepatocellular carcinoma), and Human T-cell leukemia virus-1 (T-cell leukemias).
4. Bacterial infection: in Helicobacter pylori-induced gastric carcinoma.
5. Parasitic infections : Include Schistosoma haematobium (squamous cell carcinoma of the bladder) and the liver flukes, Opisthorchis viverrini and Clonorchis sinensis (cholangiocarcinoma)
6. Radiation: Radiation-induced leukemia ,nevoid basal cell carcinoma syndrome or retinoblastoma,Prolonged exposure to ultraviolet radiation from the sun can lead to melanoma skin , the n Non-ionizing radio frequency radiation from mobile phones, electric power transmission, and other similar sources have been described as a possible carcinogen by the World Health Organization's International Agency for Research on Canceron-ionizing medium wave UVB, as the cause of most non-melanoma skin cancers,
7. Heredity: Include: certain inherited mutations in the genes BRCA1 and BRCA2 with a more than 75% risk of breast cancer and ovarian cancer, and hereditary nonpolyposis colorectal cancer (HNPCC or Lynch syndrome) which is present in about 3% of people with colorectal cancer
8. Physical agents: Prolonged exposure to asbestos, causes mesothelioma,. Other substances in this category, are synthetic asbestos-like fibers such as wollastonite, attapulgite, glass wool, and rock wool, are believed to have similar effects. Nonfibrous particulate materials include powdered metallic cobalt and nickel, and crystalline silica
9. Hormones: By promoting cell proliferation. In sex-related cancers such as cancer of the breast, endometrium, prostate, ovary, and testis, and also of thyroid cancer and bone cancer. Osteosarcoma may be promoted by growth hormones.
10. Other: Transplacental transmission of acute leukaemia, lymphoma, melanoma and carcinoma from mother to fetus has been observed.