Cancer is a group of many different diseases that have some important things in common. Cancer affects our cells, the body’s basic unit of life. Cancerous cell is larger in size than normal cell, multiplies uncontrollably, spreads to other organs and is independent of the normal regulations of the body. To understand more about cancer, it is helpful to know how normal cells become cancerous. In short it can be said that alteration or loss of good genes and development of many bad genes results in cancer.

The body is made up of many types of cells, which live under well-regulated conditions. Most of the functions of the cell are carried out under the orders of “genes”, which are DNA particles inside the nucleus of the cell. Some of the important functions of the cell are – multiplication, growth and repair and these are carried out under control of regulatory “genes”. These genes ensure that the required function is carried out only when required and stops when not required, something like ‘on’ and ‘off’ buttons. They also ensure that the normal cells do not encroach on other organs and respect cellular boundaries. For example, when there is an injury of any part of the body, the damaged tissues send a signal to the cells in the neighbourhood (the button is on!) and the cells start multiplying and on completion of healing the signals are sent again (the button is off!) and the cells stop multiplying.

When there is an alteration (mutation) of these regulatory genes, the cells behave in a different manner and when many such abnormal mutant genes (oncogenes) accumulate in the cell over the period of time, the end result is cancerous growth. The situation is like having wrong buttons on and right buttons off. The cells grow in size and number; multiply uncontrollably without any purpose. They spread to other organs and start growing there too. During their growth they can destroy the organs, impair their functions, steal the nutrition, produce many harmful substances that can lead to wasting of the body and ultimately death. This is the cancer that troubles the patient.

Cells can become cancerous if some important regulatory genes are lost completely from the cell. Other genes undergo mutations without any check (like the bad guys being active in absence of policemen) and form ‘oncogenes’ and the end result is the cancerous growth. Thus one can conclude that these regulatory genes when present normally have eliminate the mutations occurring in the body before they can cause any harm. Since these genes can prevent cancer they are appropriately referred to as ‘tumour suppressor genes’. Many such genes exist in the body and their loss results in specific cancers. They may be responsible for familial cancers, as well as faster growth in some cancers, and thus believed be very important in the genesis of cancer. It is possible that such genes prevent cancerous growth in many of those heavy smokers who do not suffer cancer.

So cancer is the end result of many genetic events as multiple mutations and loss of tumour suppressor genes.