What exactly is cancer, what do the terms 'benign' and 'malignant' signify and what does the grade of tumor mean?
To understand how we get cancer you first have to know what normal cells do. The body is made up of cells which grow and reproduce themselves in a process known as cell division. The body produces about 500,000 new cells for growth and repair every day. Normal cells have certain properties to reproduce themselves exactly and they stop reproducing at the right time. Normally cells also destroy themselves if they are damaged, they stick together in the right place and they mature.
In cancer, the cells do not obey these ‘rules’ of cell division. They do not destroy themselves if they are abnormal, they do not stick together or become mature, they do not obey signals from neighboring cells and they keep on reproducing. The result is an abnormal mass of extra cells, tissues that are called a cancer tumor, that can be made up of billions of copies of the original cancer cells.
Types of Cancer Tumor
There are two types of tumor, benign and malignant. Pathologists can tell what sort of tumor it is and what grade it is by
taking a sample, known as a biopsy, and examining it under a microscope.
The cells of benign tumors reproduce in a fairly orderly way, they are encapsulated, do not invade normal tissue, do not spread to other parts of the body and are rarely fatal unless they exert pressure on other organs (i.e. brain tumors). Malignant Tumors are very different from the cells of the surrounding tissue. They invade and destroy tissue around them. Their growth is more rapid than the tissue around them and bits of the tumor, called metastases, can break off from the primary growth and spread to other parts of the body forming other tumors.
Grades of Malignant Tumor
The grade of cancer is important to know as it can influence the planning of treatment and help estimate a patient's probable
prognosis. Tumors are graded in four degrees of severity: Grades 1, 2, 3, and 4. Doctors describe and grade tumor cells in
terms of differentiation. This refers to the behavior of the cell. The more normal the cancer cell looks (well
differentiated), the lower the grade of the cancer and in general, the less aggressive their behavior. Grade 3 and 4 tumors
are poorly differentiated, (sometimes undifferentiated) and are usually more aggressive and invasive.
