Knowing cancer
Cancer cells are out of rhythm with the rest of the body. They may multiply at abnormally fast rates, and spread uncontrolled through the tissues. Some begin to spread after as long as 10 years, others in less than a year, but in all the cases early treatment is vital. Regular health checks can help by identifying symptoms in time.
Genetic material is disrupted every day in some body cells. Only a fraction of them are affected in such a way that they could multiply into cancerous tumors, and only a fraction of those with the potential ever do.
Initiation: Cancer can be triggered by exposure of the carcinogens, to X-rays, radioactivity and ultraviolet radiation. Cells are particularly vulnerable when they are in the cell-division phase of their life cycle. So, the more frequently a particular kind of cell divides in the normal, condition, the more likely it is to develop a cancer. Cells such as those of the bone marrow, skin, the linings of the stomach & intestine replace themselves frequently and so can be seriously damaged by doses of radiation that have little effect on cells which divide less often. This is why the early symptoms of radiation sickness are diarrhea & vomiting, reddening & blistering of the skin, severe anemia and loss of white blood cells (derived from special cells in the bone marrow)
Many chemical factors are known to increase the risks of cancer,’ such chemicals are called carcinogens: Some of the polycyclic hydrocarbons, for example, which are wide spread in car exhaust fumes, factory, smoke, and cigarette smoke, are capable of inducing cancer. The polycyclic hydrocarbons in cigarette smoke may play a part in the development of lung cancer; but tobacco smoke contains other possible carcinogens, as well as some radioactive substances. In animals there are many examples of the cancer produced by viruses that convert a normal cell into one which has the potential to become malignant. This comes about because some of the genetic material of the virus is incorporated into that of the affected cell. Virus-induced cancers are rare in human beings. There are few examples of virus induced cancers in humans such as Human Papilloma Virus (HPV), Burkitt-Lymphoma (Epstein-Barr Virus) and Hepatitis B Virus.
Repairs of damage: Genetic material is damaged frequently, but only rarely are the resulting abnormal cells able to survive long enough to generate a tumor. The body has various means of carrying out repairs at cell level, an important repair agent endonuclease, the enzyme (chemical capable of speeding up reactions involving other chemicals). Very rarely people are born with a lack of endonuclease. They are more susceptible than others to skin cancer during childhood.
Cell death: Often the damage done is so severe that the cells are incapable of functioning properly. Because they cannot reproduce, the affected cells simply die out & their raw material is reabsorbed and no tumor formed.
Latent cancer: A few damaged cells survive, so that defective genes are passed on to new generations of cells. In the early stages the cells containing the malfunctioning genetic material look and behave like ordinary cells. This latent state in the development of a tumor can last for many years; the genetic weakness is present but it has no obvious effect until other factors intervene.
Immune response: The body’s immune – defense systems are able to identify and destroy foreign materials. Abnormally developing cells are often recognized and swiftly destroyed. A specialized part of the immune system known as killer cells single out diseased cells for individual destruction.
Promotion: The abnormal cells are influenced by a new agent, a “promoter”, which stimulates or allows the genetic defect to start making its effects felt. The damaged cells look different from normal healthy cells and they divide too rapidly, uncontrolled by the actual needs of the body. The result is either a benign tumor or, if the cells are capable of invading and destroying surrounding tissues, a cancer. It is not known exactly what substances are promoters of human cancers, but experiments on animals suggest that very large doses of saccharin and the cyclamates may act as the promoter of cancer of the bladder.
Invasive cancer: It is the ability to invade and destroy adjacent tissues that distinguishes a malignant tumor from a benign one. The effects of this can extend far beyond the part of body in which the tumor has appeared, because clusters of abnormal cells can be transported by the circulatory systems. Secondary cancers can become widespread throughout the body as the abnormal cells continue to develop rapidly. In addition the primary causes and the promoter agent may not be identified and may continue to cause malignant tumors.
How fast does cancer spread?
Spreading through the bloodstream, cancer of the kidney invades small veins in the kidney. Detached tumor cells are carried in the main vein of the body to the lungs, where secondary tumors grow.
Spreading through the lymph system, breast cancer invades lymph channels, which carries lumps of cancer cells to lymph nodes in the armpit. Here secondary tumors grow.
Some cancer spread rapidly, some at a slower rate, invading and destroying tissue in other parts of the body. Some such as breast cancer- are extremely variable; in older women it can spread very slowly. Here are some other examples.
Very slow small superficial tumors of the skin, such as rodent ulcers, almost never invade other tissues.
Slow Cancer of the cervix: up to 10 years before invading other tissues. Regular cervical smear tests ensure that cervical cancer is treated before it spreads.
Quite Slow Cancer of the large intestine: 5-10 years before invading; often detected early and removed.
Faster: Cancer of the stomach, cancer of the kidney, cancer of the lung, melanoma (skin cancer containing dark pigment).
1-5 years before invading because melanomas are visible in the skin, they are more often detected and removed as compared to than other fast Cancer.
Very Fast: Leukemia, testicular cancer; less than 1 year before invading. Both leukemia and testicular cancer can be treated with drugs after they spread.
Cancer may occur in any organ, tissue or cell of the body. It is not a single entity, rather a group or number of diseases which is classified according to the tissue/ cell of origin. Several hundred such classes exist under three main subtypes:
Sarcomas are cancers of the connective and supportive tissues of the body such as bone cartilage, muscles, fat, nerve, blood vessels, lymphatic tissues etc.
Carcinomas are cancers of the epithelial tissues such as skin, lining of the body cavities & organs, glandular tissues like thyroid, prostate and breast.
Leukemia and Lymphomas are cancers of the blood forming tissues and lymph nodes respectively.
