What is cancer?

Cancer is a disease condition where our own body cells start to divide uncontrollably producing large number of abnormal cells. These cells may produce cancerous tumor. If left untreated, Cancer cells spreads to the surrounding structures and eventually throughout the body.

Beginning of a Cancer

A normal cell often divides to produce more copies of itself. This is vital to replace old & worn out tissues. The rate at which the cell divides is determined by some genes in the DNA.

Sometimes our DNA gets damaged and the gene that previously controlled the rate of cell division stops working. Now the cell undergoes a vicious cycle of non-stop cell division. The resulting mass of daughter cells are all abnormal and has the same defective gene. Consequently these new cells now start rapid division in turns producing even more abnormal cell. This is how a Cancer develops. 

Cancer, Mutation, Mutagens & Carcinogens

We have already mentioned that the regulatory genes only fail when the DNA gets damaged. Any change in the structure of DNA is known as ‘Mutation ’. Although most mutations are harmless but some mutations can be dangerous if it interferers with the rate of cell division.

 Mutations may occur randomly during cell division without any definite cause. However the chances of mutation are greatly increased by exposure to certain factors. The factors that promote mutation are known as ‘Mutagen’.

The mutagens that lead to Cancer are also known as Carcinogens. From high energy radiations like X-ray/ gamma-ray, to chemicals like benzene, to certain viruses & even some bacteria are classified as Carcinogen. 

Associated terms:


It is a tumor which is unlikely to turn into cancer.


It is a tumor that has already turned into cancer.


It means that the cancer cells have spread from its original site to other parts of the body. This can spread through blood circulation or lymphatic system of the body.


Grade usually ranges from 1 to 4. Grading is done according to the characteristics of cancer cells.  The higher the number, the more different the cancer cells look from normal healthy cells. It also indicates the speed of growth. Grading helps to determine treatment option & choice of drug.


Staging describes the extent to which cancer has spread across the body. It usually ranges from stage 1 to 4. The higher the number, the more the spread, for example stage 1 indicates the cancer has not spread to distant sites, where as stage 4 indicates that the cancer has spread to multiple organs throughout the body.