Define cancer. Describe three types of cancer.Which are four danger signals of cancer ?

Explanation

1. Carcinomas. This type is mainly derived from epithelial cells. They include cervical (cervix is part of uterus) cancer. breast cancer, skin cancer, brain cancer, lung cancer, stomach cancer, etc. About 80% of all tumours are carcinomas.
2. Melanomas. Cancerous growth of melanocytes (a type of skin cells) is called melanomas.
3. Sarcomes. These cancers are located in connective and muscular tissues derived from mesoderm. Thus they include the cancers of bones, cartilages, tendons, adipose tissue, lymphoid tissue and muscles. Cancer of bones is called osteoma. Cancers of adipose tissue are known as lipomas. They are rare in humans, about 1 per cent of all tumours are sarcomas.
4. Leukemias and lymphomas. These are cancers of haematopoietic cells. Leukemias are characterised by abnormal increase of white blood corpuscles count due to their increased formation in the bone narrow. Leukemias are commonly called blood cancers. Cancers of lymphatic tissue are termed as lymphomas. Hodgkin.s disease is an example of human lymphomas, where there is enlargement of spleen and lymph nodes and increased production of lymphocytes.