Cancer
Different Kinds of Cancer Carcinomas, arise from the cells that cover external and internal body surfaces such as lung, breast, and colon. Sarcomas, arise from cells found in the supporting tissues of the body such as bone, cartilage, fat, connective tissue, and muscle. Lymphomas, arise in the lymph nodes and tissues of the body's immune system. Leukemias are cancers of the immature white blood cells.Loss of Normal Growth Control: Cancer arises from a loss of normal growth control. In normal tissues, the rates of new cell growth and old cell death are kept in balance. In cancer, this balance is disrupted. This disruption can result from uncontrolled cell growth or loss of a cell's ability to undergo "apoptosis." Apoptosis, or "cell suicide," is the mechanism by which old or damaged cells normally self-destruct.
Carcinoma in Situ: The most severe cases of dysplasia are sometimes referred to as "carcinoma in situ." In Latin, the term "in situ" means "in place“, so carcinoma in situ refers to an uncontrolled growth of cells (tumor) that remains in the original location.
Invasion and Metastasis (spread of cancer): Cancers are capable of spreading throughout the body by two mechanisms: 1. Invasion, refers to the direct migration and penetration by cancer cells into neighboring tissues. 2. Metastasis, refers to the ability of cancer cells to penetrate into lymphatic and blood vessels, circulate through the blood or lymphatic stream, and then invade normal tissues elsewhere in the body.
Malignant versus Benign Tumors: Benign tumors are tumors that cannot spread by invasion or metastasis; hence, they only grow locally. Malignant tumors are tumors that are capable of spreading by invasion and metastasis. By definition, the term "cancer" applies only to malignant tumors.
What Causes Cancer? 1. Intrinsic factors: such as heredity, diet, and hormones, behaviors, lifestyle. 2. Extrinsic factors: such as chemicals, radiation, and biological. 3. Multifactorial: in Japan, the rate of stomach cancer is higher, than in the United States. But this difference has been found to gradually disappear in Japanese families that have moved to the United States. This suggests that the risk of developing cancer is not determined primarily by heredity. The change in risk for cancer for Japanese families could involve cultural, behavioral, or environmental factors.
Tobacco Use and Cancer: Tobacco smoking is the greatest public health hazard. Cigarette smoke contains more than 24 different carcinogens. Cigarette smoking is the main cause of lung cancer and contributes to many other kinds of cancer as well, including cancer of the mouth, larynx, esophagus, stomach, pancreas, kidney, and bladder. Current estimates suggest that smoking cigarettes is responsible for at least one out of every three cancer deaths, making it the largest single cause of death from cancer.
Radiation: Low-Strength Radiation (non-ionizing): Prolonged or repeated exposure to ultraviolet radiation from sunlight is a low-strength type of radiation that can cause cancer. High-Strength Radiation (ionizing): Such as X-rays or radiation emitted from unstable atoms called radioisotopes. These two types of radiation are stronger than ultraviolet radiation, they can penetrate through clothing and skin into the body..
Infection: 1. Viruses: Few viruses that infect human cells actually cause cancer. viruses implicated in cervical cancer (HPV), liver cancer (HBV), and certain lymphomas (EBV), leukemias (HTLV), and sarcomas (KSAHV). 2. Bacteria: The bacterium Helicobacter pylori, which can cause stomach ulcers. 3. Parasites.
Cancer Risk and Aging: Because a number of mutations usually must occur for cancer to arise, the chances of developing cancer increase as a person gets older (aging) because more time has been available for mutations to accumulate. Living more, means exposed more For example, a 75-year-old person is a hundred times more likely to develop colon cancer than a 25-year-old. .
7 Warning signals (cancer societies education) Change in bowel or bladder habits A sore that does not heal Unusual bleeding or discharge Thickening or lump in the breast or elsewhere Indigestion or difficulty in swallowing Obvious change in a wart or mole Nagging cough or hoarseness CAUTION
Diagnosis of cancer: 1. Diagnosis of cancer is histopathological. 2. The importance of biological markers (BRCA1&BRCA2). 3. The importance of screening. 4. Early finding of cancer may decrease a person's risk of dying from the cancer.