Cancer – What is It?
Cancer is an abnormal and uncontrolled growth of cells that can invade nearby tissues, metastasize (spread to other parts of the body), and erode or destroy normal tissue. Cancer is an extremely complex disease that kills about 10 million people per year worldwide. It is also a major cause of morbidity and disability in the US and other nations and causes tremendous suffering for patients and their loved ones.
Most cancers start in the cells that make up tissue and then grow out of control. Cells are the basic building blocks that make up our bodies and are normally designed to grow, develop, repair and die in a precise way. But sometimes, when a cell is damaged or goes wrong, new cancer cells can form and these continue to grow. The build up of these abnormal cells over time forms a mass of tissue called a tumour or cancerous lump or growth.
The process of creating a cancer starts with changes to the DNA in the cell. These are called mutations and can be caused by many things, such as getting older or smoking tobacco or being exposed to ultraviolet radiation from the sun. Mutations can also be hereditary, meaning they are inherited from our parents and may run in families.
Once a cancer has formed, it can spread from its site of origin to other parts of the body by travelling through the blood or lymphatic system. This can stop important parts of the body from working properly, causing pain, fatigue and in some cases, death.
In multicellular organisms, like humans, most cell types have a limited number of times they can divide. When this limit is exceeded, the cell will usually die, a process known as programmed cell death. The exception to this is stem cells, which are cells that can differentiate into specialized cell types. Stem cells have a kind of replicative immortality.
The accumulating mutations in a cancerous stem cell allow it to multiply continuously and escape the normal controls on cell division. As it does so, it acquires traits that allow it to survive a wider range of conditions than its normal noncancerous cells. These include a tolerance to acidic conditions, an ability to grow faster by taking in nutrients from the bloodstream and an ability to co-opt or trick other cells into helping it multiply. These are a few of the reasons why cancers can be so difficult to treat.
Cancer is an abnormal and uncontrolled growth of cells that can invade nearby tissues, metastasize (spread to other parts of the body), and erode or destroy normal tissue. Cancer is an extremely complex disease that kills about 10 million people per year worldwide. It is also a major cause of morbidity and disability in the US and other nations and causes tremendous suffering for patients and their loved ones. Most cancers start in the cells that make up tissue and then grow out of control. Cells are the basic building blocks that make up our bodies and are normally designed to grow, develop, repair and die in a precise way. But sometimes, when a cell is damaged or goes wrong, new cancer cells can form and these continue to grow. The build up of these abnormal cells over time forms a mass of tissue called a tumour or cancerous lump or growth. The process of creating a cancer starts with changes to the DNA in the cell. These are called mutations and can be caused by many things, such as getting older or smoking tobacco or being exposed to ultraviolet radiation from the sun. Mutations can also be hereditary, meaning they are inherited from our parents and may run in families. Once a cancer has formed, it can spread from its site of origin to other parts of the body by travelling through the blood or lymphatic system. This can stop important parts of the body from working properly, causing pain, fatigue and in some cases, death. In multicellular organisms, like humans, most cell types have a limited number of times they can divide. When this limit is exceeded, the cell will usually die, a process known as programmed cell death. The exception to this is stem cells, which are cells that can differentiate into specialized cell types. Stem cells have a kind of replicative immortality. The accumulating mutations in a cancerous stem cell allow it to multiply continuously and escape the normal controls on cell division. As it does so, it acquires traits that allow it to survive a wider range of conditions than its normal noncancerous cells. These include a tolerance to acidic conditions, an ability to grow faster by taking in nutrients from the bloodstream and an ability to co-opt or trick other cells into helping it multiply. These are a few of the reasons why cancers can be so difficult to treat.