I chose to do my report on cancer because it is a subject I want to learn about and because it can probably fit 5 pages. My bibliography is on the ending of the report, my teacher helped me with it because I didnt know how to do it. Cancer is the name for tumors that are malignant. Malignant tumors do not respond to body mechanisms that limit growing. Malignant tumors show a not normal cell structure the same functional specialized cells.
Also cancer cells growing in laboratory tissue culture do not stop growing when they touch each other on a glass or other solid urface but grow in masses several layers deep they are said to lack contact inhibition. Loss of contact inhibition accounts for two other characteristics of cancer cells invasiveness of surrounding tissues and metastasis spreading via the lymph system or blood to other tissues and organs. Cells are typically controlled by growth factors competence factors that stimulate cells to enter the beginning phase of cell replication and progression factors that insure completion of the replication cycle.
The unrestricted growth rates of cells are due to the activation and lack of inhibition of oncogenes. They are cancer causing genes. Cancer tissue that grows without limits competes with normal tissue for nutrients kills the normal cells by nutritional deprivation. Cancerous tissue also causes secondary effects with the symptoms of a malignant growth caused by the pressure of the growing tumor against surrounding tissue or the metastasis of cancer cells and their invasion of other organs. Cancers are graded as to degree of malignancy on a scale of one through four the distinction between even benign and malignant neoplasms is obscure.
All organs and tissues are susceptible to cancer. A lot of human cancers may be caused or at least triggered by various chemical agents. Alkylating agents are thought to have a carcinogenic effect because they chemically alter the cell’s nucleic acids. Nitrites common additives in processed meat react with amines in the stomach to form nitrosoamines which some authorities believe may be carcinogenic to humans. Other commonly occurring carcinogens are azo dyes, polycyclic hydrocarbons, and urethane. Certain carcinogens present occupational hazards. Asbestos particles once inhaled stay in the lung and act as an irritant.
In the asbestos and construction ndustries workers have a high probability of developing a fatal cancer of the chest lining or abdominal lining 25 to 30 years after the initial inhalation of . Asbestos also has been linked to lung and colon cancers in exposed individuals. Oral cancer common in India is commonly attributed to the chewing of betel nuts. Although the apparently increasing incidence of some types of highly malignant cancers certain lung cancers and may be a result of improvements in disease detection and diagnosis cigarette smoking and an increase of atmospheric pollutants are also thought to play a part.
Increasing evidence implicates viruses in induction of cancer. In the early 20th century Peyton Rous an American virologist showed that certain fowl sarcomas could be transmitted by injection of an agent invisible under the microscope and later shown to be an RNA containing virus. Since then other oncogenic or tumor causing viruses have been identified in experimental animals. Viruses of the herpes group some of which cause cold sores and chicken pox have been shown to cause cancer in experimental animals. Recent evidence indicates that other members of the herpes group such as the virus causing infectious ononucleosis may cause human cancer.
Human papillomavirus has also been shown to cause or initiate cancers. Some types of HPV cause genital warts known as condylomata acuminata which appear to cause invasive cancer of the cervix, vulva, vagina, or penis. There is evidence of synergistic effects of smoking and some forms of HPV and cancer particularly cervical cancer in woman. HPV 16 has been shown to be associated with some forms of Kaposi’s sarcoma. Surgical removal of the warts and lesions has a 70% prevention of recurrence antiviral treatment with interferons ppear mildly successful when surgical removal is not successful.
Some cancers may be triggered by changes in the body’s internal environment as hormone imbalances. A first reported in 1970 some daughters of mothers who had been given diethylstilbestrol during pregnancy to prevent miscarriage developed vaginal adenocarcinomas as young women. There are genetic tendencies for certain types of cancer like breast or stomach cancer and certain benign tumors like certain tumors of the eye, cartilage, and skin, some of which may later become malignant.
Physical agents such as X-rays and radioactive elements re also carcinogenic the high incidence of leukemia and other cancers in Japanese survivors of the atomic bombing of Hiroshima and Nagasaki is evidence of this carcinogenic effect. In light skinned people who spend much time outdoors, sunlight may be carcinogenic. Sometimes irritations and diseases may predispose an individual to cancer, as in the occurrence of cancer of the esophagus associated with frequently swallowing very hot liquids. Symptoms are often nonspecific like weakness, loss of appetite, and weight loss.
Sometimes side effects of tumor growth are more severe than the actual effects of the malignancy like some umors secrete materials such as serotonin and histamine that can cause drastic vascular changes. A tumor of an endocrine gland such as an adrenal carcinoma may be responsible for producing enormously increased numbers of hormone secreting cells. Cancers that destroy tissue may also have serious effects like malignant destruction of bone tissue may raise the blood level of calcium. Cancers can often be detected by visual observation palpation X-ray study inspection by various optical probing instruments.
Cancers caught early before metastasis have the best cure rates. Once they are found cancers are treated by surgery, chemotherapy, and radiation. Surgery is most effective if the cancer is caught while still localized. Some cancers that spread to the lymph system have frequently prompted extensive surgical removal of tissue . Many cancers formerly treated surgically are now being attacked by other means such as radiation therapy. Use of radioactive elements specific for particular target organs such as radioactive iodine specific for the thyroid gland is effective in treating malignancies of those organs.
Lasers are used to treat certain ancers and certain subatomic particles like pions, are being used experimentally. Chemotherapeutic agents that are are used to selectively destroy cancer cells. In general they interfere with nucleic acid and protein synthesis rapidly proliferating cells like cancer cells are most susceptible. Hormones such as and which may be carcinogenic under some condition are also used in cancer chemotherapy. Currently available chemotherapeutic agents are not usually curative but merely ameliorate the severity of the disease they are often toxic to normal rapidly proliferating cells such as bone marrow cells.
A chemotherapeutic technique known as isolated perfusion can be used to minimize exposure to many toxic drugs. In this method a pump and two tubes are attached to two places in a network of blood vessels so that the drug only circulates through the part of the system that is malignant. New approaches to cancer therapy still largely in the experimental stage include immunological methods such as vaccinating against cancer causing viruses or injecting sensitized lymphocytes like antibody forming cells. Recent research is also directed toward elucidating the cellular events that are manifested s uncontrolled growth and cancer.
The fact that there are many ways to interfere with the controls on genes may help to explain why cancer is apparently caused by a diversity of agents and why agents that interfere with the expression of genetic information like nitrogen mustard, radiation, and some hormones, are sometimes carcinogenic and sometimes therapeutic. This report was very hard to do because I had to look up all these big scientific words up in the dictionay. I hope you think I did a good job and I hope to get an A+. The bibliography you wanted is below.
