Cell Division in Tumor Cells

What Is Cancer?

Cancer also called malignancy is an abnormal growth of cells. There are more than 200 different types of cancer, including breast cancer, skin cancer, lung cancer, colon cancer, prostate cancer and lymphoma. Symptoms vary depending on the type. Cancer causes cells to divide uncontrollably. This can result in tumors, damage to the immune system and other impairment that can be fatal. Some cancers can spread to other parts of the body.

Cancer starts when cells change abnormally: cancer start

Cancer starts with changes in one cell or a small group of cells. Cells produce signals to control how much and how often the cells divide. If any of these signals are faulty or missing, cells may start to grow and multiply too much and form a lump called a tumour.

Cancer grows as cells multiply over and over: cancer growth

Benign tumours are made up of cells that are quite similar to normal cells. The cancer cells grow and divide to create more cells and will eventually form a tumour. A tumour may contain millions of cancer cells. All body tissues have a layer (a membrane) that keeps the cells of that tissue inside. This is the basement membrane. Cancer cells can break through this membrane. If this happens, the cancer is called invasive. As the tumour gets bigger, its centre gets further and further away from the blood vessels in the area where it is growing. So the centre of the tumour gets less and less oxygen and nutrients. Like healthy cells, cancer cells cannot live without oxygen and nutrients. So they send out signals, called angiogenic factors, that encourage new blood vessels to grow into the tumour. This is called angiogenesis. Without a blood supply, a tumour can't grow much bigger than a pin head.

Once a cancer can stimulate blood vessel growth, it can grow bigger and rapidly. It stimulates the growth of hundreds of new small blood vessels (capillaries) to bring in nutrients and oxygen. As the tumour grows and takes up more space, it begins to press on the normal body tissue nearby. The tumour growth will force itself through the normal tissue, as in the diagram below. it will squeeze and block small blood vessels in the area. Due to low blood and oxygen levels, some of the normal tissue will begin to die off. This makes it easier for the cancer to continue to push its way through.