Cancer is a disease that occurs when abnormal cells divide without control and can spread to other parts of the body. It can be difficult to understand how cancer happens and why it develops. But there are a number of things you should know about cancer that can help you make healthy choices to stay well.
The term “cancer” refers to a group of diseases that begin in one type of cell, but then grow out of control and can spread to other types of cells in the body. The most common cancers begin in cells that line organs, such as the lungs or stomach. They may also begin in cells that make blood or in stem cells, which give rise to blood-forming cells. There are many different kinds of cancer, each named for the type of cell in which it starts.
Scientists now know that cancer is caused by a series of changes (mutations) in genes that regulate how cells normally grow and behave. These mutations cause normal cells to become abnormal and start growing and dividing without control. As a result, they form a mass of abnormal cells that is called a tumor. Over time, the tumor can grow large enough to cause symptoms and it can spread to other parts of the body through the blood or lymphatic system.
Most people with cancer benefit from early detection and treatment. This is why doctors recommend regular screening tests, such as mammograms or colonoscopies. If caught early, most types of cancer are curable.
Many factors can cause cancer, including inherited genes and certain infections. However, about 22% of cancers are due to lifestyle habits, such as smoking or a poor diet. Other risk factors include certain viruses, such as hepatitis B and C, human papillomavirus infection, and herpes simplex virus infection.
When cancer begins in a single cell, it usually grows and spreads slowly. But if it continues to grow and spread, the chances of survival decrease. A tumor that is growing and spreading quickly can be harder to treat than a tumor that has not grown or spread very much.
Cancers that have not yet spread are sometimes referred to as “primary cancers.” They can often be treated with surgery, radiation or chemotherapy. When a person’s cancer is diagnosed and treated, he or she is said to be in remission. Remission is when a person’s symptoms and side effects of treatment are reduced or disappear. Remission varies by person and depends on the type, severity and location of the cancer. Improvements in cancer treatment are causing the death rate from cancer to decline year after year. This is partly because of better diagnosis, but it is also because of better treatments. In addition, some people with cancers that have already spread to other parts of the body can still have a good outlook for a good prognosis if they receive the right treatment. These treatments can include surgery, chemotherapy, and radiation therapy.