Cancer Basics

What is Cancer?

Cells make up every part of the human body: skin, hair, nails, lymph nodes, blood and body organs. Cell division is a normal part of a cell’s life cycle and is regulated by genes (segments of DNA that determine a person’s unique make-up and how their body functions). Under healthy conditions, the process of cell division is tightly controlled with numerous checks and balances in place. Cancer cells are descendants of a single normal cell in which genetic errors, or mutations, have occurred. These errors may occur spontaneously or randomly when cells divide, or they may present themselves as a result of exposure to environmental toxins (carcinogens). Cancer occurs when these abnormal cells continue to grow at an uncontrolled rate. As these abnormal cells divide, they can eventually form a solid mass called a tumour. A malignant (cancerous) tumour will continue to grow at an uncontrolled rate and may eventually harm other areas of the body. The definition of cancer is the abnormal, uncontrolled growth of cells. Most of the time, your body will react and correct the problem without you ever knowing. Cells will detect and correct errors, or other genes will become activated and cause the mutated cell to die. The immune system will also recognize damaged cells and kill them before tumours can form and cause problems. Because of all these factors, cancers are not thought to be the result of a single event. A combination of negative events and missed opportunities are required for cancers to form.

Why Does Cancer Occur?

This is a question that scientists have been trying to answer for a long time. One main reason that cancer may develop is due to genetic errors. There are many different genes present in all cells, and each one controls a different function in the body. When errors (called genetic mutations) occur in the genes that control cell division, the result is a cell that cannot divide normally. This results in an abnormal cell that cannot properly perform its intended function. The cells of the immune system are constantly circulating in the body to identify these abnormal cells and destroy them. However, in instances where the immune system doesn’t work properly, or if the genetic mutation is too severe, these abnormal cells remain and grow. Cancer occurs when these abnormal cells continue to grow at an uncontrolled rate. As these abnormal cells divide, they can eventually form a solid mass called a tumour. A malignant (cancerous) tumour will continue to grow at an uncontrolled rate and will eventually cause harm to other areas of the body.