Background Information on Cancer
What Is Cancer3,4
Cancer is a group of more than 100 diseases caused by the uncontrolled growth and spread of abnormal cells. Tumors, or abnormal growth of tissue, may be benign or malignant. Benign tumors are usually slow-growing and not life-threatening, whereas malignant tumors (or cancers) are made up of cells with abnormal genetic material (or DNA) and usually grow more rapidly. Malignant tumors (cancers) have a tendency to invade neighboring tissues or organs and to travel and grow in other areas of the body (i.e., to metastasize). If the spread of the cancer is not stopped, cancer cells invade vital organs which can result in death. Cancer cells may remain at their original site (local stage), spread to an adjacent area of the body (regional stage), or spread throughout the body (distant stage). Cancers at the local, regional or distant stage are considered invasive. A very early cancer found in only a few layers of cells, called in situ cancer, is considered non-invasive.
What Causes Cancer3,4
Cancers are caused by a variety of factors working alone or in combination. Some cancers are caused by external factors such as tobacco, diet, certain chemicals, radiation, and viruses. Other cancers are caused by internal factors such as hormones, immune conditions, and inherited genetic mutations. Usually ten or more years pass between exposure to a factor that causes cancer and detectable disease.
Cancer Incidence And Mortality In The U.S.3,4
Cancer is the second leading cause of death in the U.S., with 1,228,600 new cases and 564,800 deaths estimated for 1998. Over the past 50 years, the death rate from cancer has increased steadily, due mainly to a large rise in lung cancer death rates resulting from smoking. During the past few years cancer incidence and death rates have begun to decrease, possibly as a result of healthier lifestyles, particularly decreases in smoking. Cancer occurs in people of all ages, but its occurrence increases greatly in people over 45 years of age. However, it is also the leading cause of non-accidental death among U.S. children under age 15. Men have a higher mortality rate due to cancer than women, and blacks have the highest cancer mortality rate of any major racial group. In the U.S., men have about a 1 in 2 lifetime risk of developing cancer and women have about a 1 in 3 lifetime risk. (These figures do not include basal and squamous cell skin cancers or in situ cancer except for the bladder.) Compared to earlier years a much higher percentage of people diagnosed with cancer now are surviving. Now, about four out of every ten people diagnosed with cancer will survive for at least five years.
Sources Of Information About Cancer
For additional free information on cancer these organizations may be contacted: