The Basics of Cancer


Cancer is a disease that develops when cellular changes cause uncontrolled growth and division of cells. It can lead to tumors, damage to the immune system, and other impairment that can be fatal. It affects about 1 in 3 people in the United States and is the leading cause of death among adults.

The origin of cancer is still unclear. Some scientists believe it arises from chronic irritation of tissue or a genetic mutation that causes the development of a single abnormal cell. Other ideas suggest that cancer can occur as a result of exposure to radiation or other substances that damage tissue and cells.

Most types of cancer are caused by a change in one or more genes. These changes, or mutations, enable precancerous cells to acquire some of the characteristics that eventually produce malignant growth of cancerous cells (see “How does cancer develop?”).

These genetic changes often occur in groups, so that each individual tumor has its own unique set of mutations. Each of these mutations enables cancerous cells to divide in a way that is different from normal cells, allowing them to grow and form tumors that spread throughout the body.

Another important characteristic of cancer is that the cancerous cells are capable of dividing for an apparently unlimited number of generations, unlike normal cells, which usually only divide once or twice. The ability to divide for so long is why tumors can multiply indefinitely, and it’s why they are able to invade other tissues, too.

There are also many ways that cancer cells can influence other healthy cells, blood vessels, and molecules in the body. These can make the tumor grow and thrive, or they can help it hide from the immune system so that the body’s normal defenses won’t recognize the tumor and destroy it.

Some cancers can be cured with surgery, chemotherapy, radiation therapy, or other treatment methods. Others are treated with medications and other therapies, called targeted drug therapy, that target specific abnormalities in cancer cells.

Diet and lifestyle are also known to play a role in cancer risk. Eating a healthy diet with plenty of fruits, vegetables and whole grains can help lower your risk of getting cancer. Avoiding high-fat, processed meats and other foods that are known to increase cancer risk can help too.

Inherited mutations are also important in some cancers. The National Cancer Institute estimates that inherited mutations contribute about 5 to 10 percent of all cancers.

These mutations may be inherited through a parent or a child, or they might arise randomly as a result of bad luck as cells divide in the body. They might also be a result of environmental factors, such as air pollution or exposure to chemicals.

The best way to lower your risk of developing cancer is to maintain a healthy diet and lifestyle, and to avoid exposure to toxins that can damage your cells. In addition, you might consider getting regular screening tests, such as colonoscopy or a Pap test, to detect cancer early when it is easier to treat.