What is Cancer
a. Types of Cancer
There are five main types of cancers according to the type of tissue affected. Cancers are named according to the tissue from which they arise.
i. Carcinoma :
Cancer that arises from epithelial tissue covering or lining te body organs is known as carcinoma. It includes breast cancer, lung cancer, cancer of stomach, skin cancer, etc.
Cancer that arises from connective tissue is called sarcoma. It include bone tumors (osteosarcoma), muscle tumors (myosarcoma), cancer of cartilage (chondrosarcoma) and cancer of adipose tissue (liposarcoma).
Cancer that arises from lymphatic tissue, called lymphoma. It occurs in the lymphatic nodes, spleen and tissues of immune system.
It is a type of blood cancer in which there is excessive formation of white blood cells (WBCs) or leucocytes in the bone marrow. People suffering from leukemia have very high leucocyte count. The blood contains millions of abnormal immature WBCs or leuococytes tat are incapable of figting infections. Tere are vaarious types leukemia suc as monocytic leukemia, lymphoblastic leukemia etc.
Adenocarcinoma cancer arises in troid, pituitary adrenal and oter glandular tissues.
b. Causes of Cancer:
Although, it is not very clear as to ow te cancer is caused, several factors are now known to be cancer-causing i.e. carcinogenic. These factors are as follows:
Several chemicals are known to induce cancer. These include nicotine, caffeine, products of combustion of coal and oil. Several polycyclic hydrocarbons, some sex hormone and steroids, if given or secreted in large amounts, may cause cancer. Breast cancer seems to ave hormonal relationship. It is more commonly observed in women who avoid breastfeeding.
Te x-rays, gamma rays, cosmic rays, ultra-violet rays, etc. are carcinogenic. Incidence of skin cancer is higher in people working in sunny areas due to UV radiation in the sunlight.
Viruses causing cancer have genes called viral oncogenes (v-onc genes). These viruses are also called oncogenic viruses. e.g. EBV(Epstein-Barr virus), HPV(human papilloma virus) etc.
Several genes called cellular oncogenes (c-onc genes) or proto-oncogenes have been identified in normal cells which when activated under certain conditions could lead to oncogenic transformation of cells.
Different types of addiction like smoking, chewing of tobacco lead to cancer of mouth, lips and lungs. Alcohol consumption may result in cancer of the esophagus, stomach, intestine and liver. Drugs also cause cancer e.g. Marijuana, anaerobic steroids, etc.
c. Treatment of Cancer:
Cancer treatment consists of combination of a number of therapies which are as follows:
Chemotherapy comprises the administration of certain anticancer drugs. Te anticancer drugs check cell division by inhibiting DNA synthesis or are more toxic to cancerous cells tan to normal cells. Chemotherapy may lead to air loss or anemia but bot gets corrected after the treatment is stopped.
It is used in addition to chemotherapy. In radiotherapy, the basic principle is to bombard the cancerous cells or tissue wit te rays from radioactive materials such as cobalt, iridium and iodine. The rays x-rays, gamma rays and charge particles are used to destroy the cancerous tissue or cells but cause minimum damage to surrounding normal tissue or cells.
In surgery, the entire cancerous tissue or cells are removed surgically. It as a limited utility. In certain cases such as breast tumor or uterine tumor, the surgery is more effective, but other treatments are also given to kill any cancerous cell that may have been escaped in surgery.
Tumor cells have been sown to avoid detection and destruction by the immune system. Therefore, te patients are given substances called biological response modifiers such as alpha interferon which activates the immune system and helps in destroying the tumor.
v. Supportive therapy:
Supportive therapy is used to treat symptoms of cancer and side effects of cancer treatments. Objective of this therapy is to improve the quality of life of cancer patients. This therapy varies depending upon condition of individual patient.