What is cancer?
The word “cancer” describes any disease in which abnormal cells develop, divide uncontrollably and have the ability to infiltrate and destroy normal body tissue. Normally, cells grow and divide to produce more cells as they are needed to keep the body healthy. Sometimes, this orderly process goes wrong. New cells form when the body doesn’t need them, and old cells don’t die when they should. The extra cells form a mass of tissue called a growth or tumor. Not all tumors are cancerous; tumors can be benign or malignant.
Benign tumors are not cancerous. They can often be removed and, in most cases, they don’t come back. Cells in benign tumors don’t spread to other parts of the body. Most importantly, benign tumors are rarely a threat to life. Malignant tumors are cancerous. Cells in malignant tumors are abnormal and divide without control or order. Cancer cells invade and destroy the tissue around them. They can also break away from a malignant tumor and enter the bloodstream or lymphatic system. The lymphatic system carries lymph and white blood cells through lymphatic vessels (thin tubes) to all the tissues of the body. By moving through the bloodstream or lymphatic system, cancer can spread from the primary (original) cancer site to form new tumors in other organs. The spread of cancer is called metastasis.
What causes cancer?
Cancer is caused by changes in genes that normally control the growth and death of cells. There are many factors that increase the chance of developing cancer, including lifestyle, environment and genetic risk factors. There are also certain viruses that increase the risk of developing cancer.
Certain lifestyle and environmental factors can change some normal genes into genes that allow the growth of cancer. Many gene changes that lead to cancer are the result of:
- Tobacco use
- Poor diet
- Obesity
- Lack of physical activity
- Exposure to ultraviolet (UV) radiation from the sun
- Exposure to carcinogens (cancer-causing substances) in the workplace or in the environment
Viruses such as the human papillomavirus (HPV), hepatitis B and C (HepB and HepC), and human immunodeficiency virus (HIV) increase the risk of some types of cancer. However, cancer itself is not contagious. A person cannot catch cancer from someone who has the disease.
Changes, called alterations or mutations, in certain genes make some people more susceptible to developing breast, prostate or ovarian cancer. Some genetic alterations are inherited (from one or both parents). However, having an inherited gene alteration doesn’t always mean that the person will develop cancer; it only means that the chance of getting cancer is increased.
Source: http://www.omhrc.gov/templates/browse.aspx?lvl=3&lvlid=19
Office of Minority Health, US Dept of Health & Human Services