Cancer is new growth of tissue resulting from rapid production of abnormal cells Cancer is not a single disease but includes a number of diseases classified according to the tissue and type of cell in which new growth occurs, here are three major subtypes are Sarcomas, Carcinomas, Leukemias and Lymphomas.
More than 1,350,000 new cases of cancer occur in the United States each year. Cancer is the second leading cause of death in the nation, and the leading cause of death from disease in children between the ages of 1 and 14. The figures for the United States are 217/100,000 men and 137/100,000 women. The most death causing cancers are lung cancer- 1st in each sex, colorectal cancer- 2nd in both sexes, and breast and uterine cancers in women, and prostate cancer in men. Since 1949 death from cancer in the United States has been higher among men than women. The sex ratios of different cancers vary considerably. Death from cancer is higher among blacks than among whites.
A cancerous growth, is clonal- all its cells are descendants of a single cell. Fatal cells are unable to mature into an adult. These cells may form a mass called a tumor, which enlarges and continues to grow. Not all tumors are fatal; the greatest number are benign, or non-life-threatening. Cancer cells may retain the physical and biological characteristics of the tissue in which they originated. Pathologists can often determine the site of origin of a metastatic tumor by microscopic examination of the cancerous tissue. The less closely a cancer resembles the tissue in which it first grew, the more fatal and rapidly invasive it tends to be. Over time, a tumor may develop increased resistance to various forms of treatment.
Cancer may be caused by a number of factors that include inheriting a gene that give an individual a particular type of cancer, contracting a virus that causes a specific form of cancer, being exposed to certain types of radiation and particular chemicals that cause cancer. Changes in the immune system and exposure to certain environmental factors can also cause cancer. The earlier cancer is treated,...