Cancer is a disease that develops when cells grow out of control. Cancer can be any type of cell, but it most often starts in cells that line blood vessels and produce hormones. These cells normally grow and divide to make more cells, but sometimes these cells can become abnormal and start growing out of control. As these cancer cells multiply, they can crowd out normal cells and grow into a mass that is called a tumour. Cancer can also spread to other parts of the body through the blood and lymphatic system. These new sites of cancer are often called metastases.
Normally, genes carry instructions that tell cells when to grow and die. Sometimes, changes (mutations) in genes can cause these instructions to break down. As a result, cells don’t die when they should and keep making more cells that the body doesn’t need. Over time, this can build up to form a tumour.
The types of cancer that can form vary widely, but they all start when cells grow out of control and do not die as they should. The resulting tumour can outpace the body’s ability to provide oxygen and nutrients to these growing cells.
Most cancer treatments are aimed at killing or destroying the cancer cells and stopping them from spreading. Treatments include surgery, radiation, chemotherapy and other drug therapy. Some types of cancer are treated with bone marrow transplantation, which replaces damaged stem cells in the bone marrow with healthy ones. This can be done with your own stem cells or with those donated from another person.
Some cancers can also be treated with immunotherapy, which uses your own immune system to fight the cancer. Other therapies, such as hyperthermia, use targeted heat to kill cancer cells without harming surrounding tissues. Hormone therapy stops your natural hormones from helping some cancers to grow.
Some cancers are more likely to grow and spread than others. You can reduce your risk by avoiding things that can damage your cells, such as too much sun exposure and tobacco smoke. A healthy diet is also important. You should eat lots of fruit and vegetables, whole grains and lean protein and cut back on foods and drinks that are high in fat and sugar. Drinking alcohol can increase your risk of developing six different types of cancer, so try to limit your intake. Taking part in clinical trials that test new treatments is also an option. These trials can help scientists find ways to improve cancer care in the future.