Cancer is unregulated cell growth which leads to formation of tumors in areas of the body. Cells can be benign, meaning they are inert and do not spread or they can be cancerous which means the having the ability to spread to other areas of the body through the blood or lymphatic system. Tumors can restrict normal body processes and release hormones and enzymes that will alter the internal environment. Cancerous cells do not follow the normal cell cycle, base sequence is altered so that cell death is not observed – the cell can continuously grow and multiply. Tumor formation starts with a cancerous cell that is transported around the body, infecting cells in contact and multiplying to produce a population of cancerous cells. The process of metastasis describes the condition when areas of the body are infected by cancerous cells.
Genes contain coded information that control cell division, tumor suppressor cells, cell programmed death and DNA repair activities. Any mutation to base sequence can change any of those controllable variables, producing cancerous cells that does not undergo apoptosis and rapidly divides. Mutations in base sequence of DNA can give rise to the expression of cancerous cells. The cause of cancer is not fully understood, a small portion of cancer is attributed to hereditary defects but daily activities affect the risk of cancer such as exercise, diet and lifestyle. Carcinogens are substances found in the environment that cause mutations in genes, examples are asbestos, radiation and gamma rays.
Treatment of cancer can vary depending on degrees of growth and spread, but the most common forms are surgery, chemotherapy, and radiative therapy. In surgery, the tumor is removed and depending on the stage of cancer, it maybe be eradicated or further spreading may occur. Chemotherapy uses selective chemicals to kill cancerous cells; it may destroy healthy tissues as a side effect. Radiative therapy uses concentrated ionizing radiation to kill cancerous cells.