What is meant by Cancer?

Cancer is a large, heterogenous class of diseases, characterized by uncontrolled growth of cells that invade the surrounding tissues and destroys them.

In simple terms, cancer is a disease that results from the abnormal growth and differentiation of the tissues.

What are the synonyms of Cancer?

The synonyms of cancer are malignant neoplasm and malignant tumor.

How do tumor cells spread to other parts of the body?

Some of the tumor cells spread to other parts of the body through lymphatic system or through the blood stream. Such group of cells that spread to other parts of the body is known as malignant tumors and the cells that do not spread to other body parts are known as benign tumors. The process of spreading of cancerous cells to other parts of the body is known as metastasis.

Incidences of Cancer:

Cancer is the major cause of death in the developed nations. Major deaths in UK are caused due to lung cancer, bowel cancer, breast cancer and prostate cancers. The cancer may develop in people of any age, but the incidence of cancer increases with increasing age. The common sites for the development of cancer are colon, lung, breast and prostate.

What is meant by tumor?

Tumor is also called as neoplasm. Tumor or neoplasm is a mass of tissue in which there is an excessive growth rate without any coordination when compared with other normal tissues.

What is Oncogenesis and what are the theories of oncogenesis?

Oncogenesis is a process that involves the transformation of normal cells into cancer cells.

Abnormalities of tumor suppressor/inducer genes:

Several proteins like p53 proteins are produced within the cells, whose function is to limit the cell division and to regulate certain parts of the cell cycle. The genes that code for these proteins are known as anti-oncogenes as they suppress the cell growth. The failure of anti-oncogenes leads to unregulated cellular division, which is the main characteristic of the cancer cells.

Other groups of genes like proto-oncogenes are also present, which produce proteins and other substances that enhance cellular growth and proliferation. Excessive activity of these genes causes excessive cellular division and growth. Lack of regulation of these genes also results in abnormal growth of cell division and its growth.

What is meant by carcinogenesis?

Carcinogenesis is a complex, multi stage process. This process involves many genetic changes and epigenetic factors like hormonal, co carcinogen and tumor promoter effects. These factors alone do not produce cancer but may increase the genetic mutations that eventually result in cancer.

Main categories of genetic change:

Activation of proto-oncogenes to oncogenes:

Proto-oncogenes are the genes that control cell division, apoptosis and differentiation. These genes may get converted to oncogenes that induces malignant change by viral or carcinogen action.

Inactivation of the tumor suppressor genes:

Tumor suppressor genes are also known as anti-oncogenes. Anti-oncogenes are present in all the normal cells of the body and have the ability to suppress the malignant change. Occurrence of mutations in these genes result in many types of cancer. If there is loss of function in the tumor suppressor genes, it will be a critical event in carcinogenesis.

The researchers have identified 30 tumor suppressor genes and 100 dominat oncogenes. The malignancy will occur as a result of point mutations, gene amplification or chromosomal translocation, caused by viruses or chemical carcinogens

  cancer, Carcinogenesis, Cell division, Cell growth, Conditions and Diseases, Metastasis, Oncogene, Tumor, Tumor suppressor gene