What Causes Cancer?
Cancer is a disease that occurs when cells in the body grow and multiply out of control. These abnormal cells form a mass of tissue called a tumour. Cancer is different for everyone and can affect any part of the body. There are many types of cancer but they all start in the same way – a change (mutation) in a gene causes cells to become abnormal and to grow without control or order.
The human body is made up of trillions of cells. Over a lifetime, most cells get old and die. New cells replace them and the cycle repeats itself millions of times a day. Cancer develops when something goes wrong with this process and the cells keep making too many new cells or the cancer cells don’t die when they should. The extra cells can grow out of control and crowd out normal cells and stop them from working normally. Cancer cells can also spread to other tissues and organs in the body through the blood or lymphatic system. This is called metastasis.
We don’t fully know what causes most cancers but we do know some things that make a person more likely to get them. These are known as risk factors and include things you can do or be exposed to, like smoking, UV light from sunlight and certain chemicals. These cause a person’s cells to develop mutations more often than they would without the risk factors. Some of these mutations can be passed on from parents to their children through genes. These genetic changes are called inherited cancers.
Many people have mutations in their genes that can lead to cancer but they don’t develop it. It is thought that this is because other influences, such as viruses and cancer-causing chemicals, overwhelm or outweigh the influence of these inherited gene changes.
Most people with cancer have no obvious warning signs or symptoms until the cancer is advanced. This is because most cancers do not produce any symptoms in the early stages, and some do not produce any symptoms at all. There are some warning signs and symptoms that can occur in all types of cancer, including pain (tumors in bones), lumps or swelling (cancers of the breast and nipple), fatigue or breathlessness (cancers of the lung), weight loss, and bleeding from the bowel or nose (cancer of the colon).
All cancers are classified into groups based on where they started in the body. These groupings are also used to help doctors decide how to treat the cancer and what its prognosis is. The most common types of cancer are breast cancer, bowel cancer and lung cancer. Each of these is then further divided into different types based on the type of cell it started in, for example skin cancers such as basal cell carcinoma and squamous cell carcinoma, or blood cancers such as leukemia.
Cancer is a disease that occurs when cells in the body grow and multiply out of control. These abnormal cells form a mass of tissue called a tumour. Cancer is different for everyone and can affect any part of the body. There are many types of cancer but they all start in the same way – a change (mutation) in a gene causes cells to become abnormal and to grow without control or order. The human body is made up of trillions of cells. Over a lifetime, most cells get old and die. New cells replace them and the cycle repeats itself millions of times a day. Cancer develops when something goes wrong with this process and the cells keep making too many new cells or the cancer cells don’t die when they should. The extra cells can grow out of control and crowd out normal cells and stop them from working normally. Cancer cells can also spread to other tissues and organs in the body through the blood or lymphatic system. This is called metastasis. We don’t fully know what causes most cancers but we do know some things that make a person more likely to get them. These are known as risk factors and include things you can do or be exposed to, like smoking, UV light from sunlight and certain chemicals. These cause a person’s cells to develop mutations more often than they would without the risk factors. Some of these mutations can be passed on from parents to their children through genes. These genetic changes are called inherited cancers. Many people have mutations in their genes that can lead to cancer but they don’t develop it. It is thought that this is because other influences, such as viruses and cancer-causing chemicals, overwhelm or outweigh the influence of these inherited gene changes. Most people with cancer have no obvious warning signs or symptoms until the cancer is advanced. This is because most cancers do not produce any symptoms in the early stages, and some do not produce any symptoms at all. There are some warning signs and symptoms that can occur in all types of cancer, including pain (tumors in bones), lumps or swelling (cancers of the breast and nipple), fatigue or breathlessness (cancers of the lung), weight loss, and bleeding from the bowel or nose (cancer of the colon). All cancers are classified into groups based on where they started in the body. These groupings are also used to help doctors decide how to treat the cancer and what its prognosis is. The most common types of cancer are breast cancer, bowel cancer and lung cancer. Each of these is then further divided into different types based on the type of cell it started in, for example skin cancers such as basal cell carcinoma and squamous cell carcinoma, or blood cancers such as leukemia.