Bodies are made up of trillions of cells that group to form tissues and organs. Genes inside each cell’s nucleus tell it when to grow, work, divide and die. But when there is a change or damage in our DNA, a gene can mutate and not work properly because the instructions get mixed up. This can cause resting cells to divide and grow out of control, leading to cancer. Gene mutations can be triggered by aging or exposure to harmful substances, including cigarette smoke, alcohol, or ultraviolet (UV) radiation. Although there are several forms of cancer – they can all be traced back to the uncontrolled and abnormal growth of cells.
How It Grows
Cancer cells are different from normal cells because gene mutations make them:
– Divide out of control
– Stay immature
– Steer clear of the immune system
– Ignore signals telling them to stop dividing or die
– Spread to other parts of the body
– Damage tissues and organs
How It Spreads
As a cancerous tumor gets bigger, the cancer cells can spread to the surrounding tissues and structures and start pushing on normal tissue beside the tumor. These cells also make enzymes that break down normal cells and tissues as they spread. Cancer that grows into tissue nearby is called a local invasion or invasive cancer.
It can also spread from where it originated to other parts of the body. This is called metastasis which can happen when cancer cells break away from the tumor and move to a new location in the body either through the blood or lymphatic system.
Most cancers can spread to just certain areas of the body which has helped doctors develop staging systems that classify cancers based on information available about where the cancer is in the body and whether or not it has spread from where it started. Many cancers follow a staging system from I to IV.
Knowing how a particular cancer spreads and where it may spread helps doctors predict how exactly the cancer will grow which also helps them plan treatments and give appropriate supportive care.
Cancer can spread to anywhere in the body but is most likely to spread to lymph nodes, the brain, the liver, bones, or the lungs.