Introduction to Cancer

Cancer is not just one disease, but a large group of almost one hundred diseases. Its two main characteristics are uncontrolled growth of the cells in the human body and the ability of these cells to migrate from the original site and spread to distant sites. If the spread is not controlled, cancer can result in death.

Cancer, by definition, is a disease of the genes. A gene is a small part of DNA (Deoxyribo Nucleic Acid), which is the master molecule of the cell. Genes make “Proteins”, which are the ultimate workhorses of the cells. It is these proteins that allow our bodies to carry out all the many processes that permit us to breathe, think and move. In a healthy individual, the immune system can recognize the neoplasmic cells and destroy them before they get a chance to divide. However, some mutant cells may escape immune detection and survive to become tumors or cancers.

Tumors are of two types, benign or malignant. A benign tumor is slow growing, does not spread or invade surrounding tissue, and once it is removed, it doesn’t usually recur. A malignant tumor, on the other hand, invades surrounding tissue and spreads to other parts of the body. If the cancer cells have spread to the surrounding tissues, then, even after the malignant tumor is removed, it generally recurs. A majority of cancers are caused by changes in the cell’s DNA because of damage due to the environment. Environmental factors that are responsible for causing the initial mutation in the DNA are called Carcinogens, and there are many types.