The third classification used in cancer treatment is called the staging system. Staging has a number of purposes.
• It is a useful way of identifying the "extent" of the tumor—its size and the degree of growth and spread.
Obviously, if a tumor is found in only one place it is in an early stage. If it has spread to some distant part of
the body or is found in several places, it is in an advanced stage.
• It provides an estimate of the prognosis since the chance of cure decreases as you move across the categories
into more advanced or extensive stages.
• It provides a common and uniformly agreed upon set of criteria against which doctors around the world can
compare treatments for a specific stage of tumor. They can then know that if one treatment has better results
than another, the difference is really due to the treatment and not to differences between patients or the stages
of the disease.
• It is generally the most important factor in deciding on the appropriate treatment.
The TNM System All kinds of staging systems have been developed for different kinds of cancer. But in the past few years a lot of thought and effort has been going on around the world to develop a relatively uniform classification system.
This system is known as TNM. T stands for the size of the tumor, N for the degree of spread to lymph nodes , and M for the presence of metastasis . A number is added to each of these letters to indicate degrees of size and spread.
