What is cancer?

    At its core, cancer (tumor) is caused by uncontrolled cell growth. Our body is made up of trillions of cells, and all cells work together. In a tumor, one of those cells stops responding to normal signals that instruct cells to grow, stop growing or even die. Cancer cells still have many of the same needs and characteristics as normal cells, but they no longer rely on the control that allows our body to function smoothly. The process of changing normal cells to behave so abnormally takes a long time and is often triggered by external influences. The following paragraphs describe the difference between normal cells and cancer cells and outline the steps for normal cells to become cancer cells.

    Cancer is actually a generic term used to describe a large group of related diseases. Each type of cancer is unique, with its own genetic changes and growth characteristics. Some tumors grow very fast while others take many years to become a threat to the patient. These differences between different cancer types (even different types on the same organ, such as different types of breast cancer) are one of the main reasons why cancer treatment is so difficult.

    In addition to the differences between different cancer types, all cancer types do have some common characteristics, and these common characteristics are the basis of cancer treatment and research. It is very important to understand the basic and shared characteristics of cancer. This can provide us with options for studying how to detect, diagnose and treat.

    A lot of changes must have taken place from normal cells to cancer cells. A single cell forms a mass of cancer cells (i.e. tumors), which then require more changes to grow and spread. Douglas Hanahan and Robert Weinberg have written an excellent review article describing models of tumor growth and spread. The information presented in the rest of this page can be found in more details in their article.