What is Cancer?

Cancer is a disease that develops when normal cells in the body begin to grow out of control and form a mass of tissue called a tumor. The cancerous cells can also spread to other parts of the body and disrupt the normal functions of those tissues. Cancer can be caused by many things, including lifestyle choices and genetic factors. Some types of cancer may be preventable.

When a person has cancer, they may experience emotional, physical and financial problems. Some cancers can be prevented by eating a healthy diet, avoiding excessive sun exposure and using birth control for women. Some cancers are treated with medication, radiation therapy or surgery. Cancer treatments are constantly improving, and the death rates for some cancers are dropping yearly.

Most people diagnosed with cancer have some type of symptom, such as unusual pain or abnormal bleeding. Other cancers are discovered by chance, such as during a medical examination for another condition or after a screening test like a colonoscopy, mammography or Pap test. People who have had cancer before are at a higher risk for the disease returning.

It is thought that cancers develop when mutations occur in cells and the cell’s DNA (genetic code) becomes damaged. Mutations in DNA can cause the cell to divide too often or not die when it should. In some cases, the mutations in DNA can cause the cell to grow out of control and form a malignant or cancerous tumor. The cancer can then spread to other areas of the body through blood or lymph.

There are more than 100 different kinds of cancer. Each type of cancer grows in a different way and affects the body in a different way. Some cancers, such as leukemia, do not form a tumor.

Some cancers are not preventable, such as nonmelanoma skin cancer and lung cancer. However, the most common cancers can be prevented or detected early by getting regular health exams and screening tests. Many of these tests include a physical exam, blood work, imaging studies and a pelvic exam for women. The most important screening test is the Pap test for women. Having an annual mammogram and regular blood work for men are also good ways to prevent some cancers.

In the past, doctors believed that cancers were infectious diseases or were caused by chronic irritation. Some of these ideas grew out of observations made more than 2,300 years ago by Hippocrates, who noticed that the long, distended veins of some breast cancers looked similar to the claws of a crab.

Research has shown that certain lifestyle choices increase the risk of cancer, such as smoking and heavy drinking. A healthy diet with lots of fruits and vegetables, whole grains and lean protein helps to reduce the risk for all types of cancer. Avoiding too much sun and using sunscreen when in the sun can also reduce the risk of skin cancer. In addition, exercise is linked to a lower risk for some cancers.