Cancer, as a disease, has existed all along with man. Hippocrates, twenty-five centuries ago, called it karkinois because the swollen blood vessels going and coming from the tumour mass, gave the appearance of the claws of a crab. Susruta described cancer as a tumour which would ulcerate and would not cure and “sow its seeds in other parts of the body”.
First, 80% of all cancers are associated with environmental causes like smoking, chewing tobacco, alcohol, radiation, and drugs.
There are cases of some families, several members of which have suffered from cancer. In the laboratory, scientists have been able to propagate some strains or breed of mice in which a large number of the males developed lung cancer and over 90 per cent of the females breast cancer. A careful analysis of data shows that certain types of cancer arc hereditary and there is a likelihood of cancer of a particular tissue or organ developing in the descendants of persons who have suffered from cancer.
One of the biggest problems with cancer is its spread in different parts of the body. This spread occurs through any or all of the three following routes:
All living things such as germs, insects, animals and human beings are made of numerous cells. Human body itself is made up of millions of cells that are specially adapted to carry out particular functions—such as the sex cells, sperms and ova, carry out the functions of reproduction.
Cancer occurs more often in people after 50 or 60 years of age. In still older people, i.e. 80 years or above, some characteristics of cancer have been noted during life and in post-mortem studies of people who have died of causes other than cancers.
Some cancers occur more often in children. The following table shows their type and the percentage of the total cancers in childhood.
Carcinoma: Any cancer that arises in epithelium, the tissue that lines the skin and internal organs of the body.
Sarcoma: Any cancer of connective tissue. These tumours may occur in any part of the body, as they arise in the tissues that make up an organ rather than being restricted to a particular organ. They can arise in fibrous tissue, muscle, fat, bone, cartilage, blood and lymphatic vessels, etc.
As in any other disease, in cancer also, both the environmental as well as the genetic factors, play a role in the causation of the disease. Over the last few decades, it has been found that the environment plays a prominent role in the causation of most cancers. 80 to 90 per cent of all cancers are said to be dependant directly or indirectly on environmental factors. Cancer problem in the world and in India is fast increasing with the increasing industrialisation and the presence of innumerable chemicals and fumes in the environment, changes in life-style including smoking and eating habits.
Tobacco tar obtained after distillation of tobacco and the same applied on the shaved skin of the mice for some weeks, produced in the skins of only some animals the cancerous changes.