Malignant Tumor Is An Abnormal

Written by docteam Tuesday, 13 April 2010 21:15

Malignant tumor is an abnormal, seemingly unrestricted growth of cells that tend to invade and destroy surrounding tissues and to transplant themselves through the lymphatic system or bloodstream to to other parts of the body. These cells threaten life unless removed early, and they may recur after surgical removal if any portion of the tumor remains.

Cancers may affect any part of the body, but the skin, lungs, rectum, breasts, and uterus are the sites most commonly affected. Some 420.000 Americans die of cancer annually, and an estimated 1 million are diagnosed as having it. Most cases occur after the age of 40, although there are many cases in children and youth.

Cancer are named according to the type of tissue in which they originate. Carcinomas are malignant tumors originating in the epithelial tissue (skin, glands, and mucous membranes of the alimentary canal, respiratory tract, or genitourinary system). Sarcomas are malignant tumor originating in connective tissue, bones, tendons, fat and muscles. Cancer of the blood forming organs, or leukemia, and its increasing prevalence are mentioned in our discussion of disorders of blood.

The overal incidence of cancer has decreased slightly in the past 25 years, but there have been sharp changes in the incidence of certain types of cancer. The occurrence of lung cancer, especially amon men, has risen sharply in the last 35 or 40 years, mainly because of cigarette smoking. On the othe hand the death rate from stomach cancer has dropped over 50%. There has been an unexplained increase in leukemia but a sharp decrease in the death rate from uterine cancer. The latter relates to earlier treatment and to the wider use of the Papanicolaou vaginal smear test in detection.

Cancer reflects a disturbance in normal cell growth and reproduction that we do not yet understand. It is known, however, that some form of chronic irritation may be an inciting cause. A pigmented mole that is rubbed constantly by clothing may develop into a cancer. No suspected growth should be squeezed or manipulated. Workers in certain occupations who are exposed to irritant chemicals often develop cancer on the exposed parts of the body.

Radiologists have had a higher rate of leukemia than people who are not so exposed, as has the population of Hiroshima and nagasaki who survived exposure to the prototype atomic bomb. Persons at the early part of the century who were employed in painting watch dials with radium developed bone cancer. And perhaps above all, most forms of skin cancer are caused by the ultraviolet rays of sunlight.