Cancer Basic biology and radiothera.pptx

radiotherapy

1. Disease characterized by uncontrolled growth of cells. Meaning of Radiotherapy What is tumor ? Although   people   of   all ages develop cancer, most types are more common in people over the age of 50. Cancer usually develops gradually over many years, the result of a complex mix of environmental, nutritional, behavioral, and hereditary factors . causes of cancer are not completely known, but certain lifestyle choices can dramatically reduce the risk of developing most types of cancer Non-smoking, eating a healthy diet, and exercising moderately for at least 30 minutes each day reduce cancer risk by more than 60 percent. Radiation Therapy External Beam Therapy or Teletherapy BrachyTherapy or Endocurie Therapy Nuclear Medicine

2. HOW CANCER DEVELOPS A healthy human body is composed of 30 trillion cells, most of which are in constant turnover as cells die and others reproduce to replace them in an orderly fashion. This cell division cycle proceeds under the regulation of the body’s intricately tuned control system. This control system ensures that cells only divide when needed, so that organs and tissues maintain their correct shape and size. If this system fail, a variety of backup safety mechanisms prevent the cell from dividing uncontrollably. In order for a cell to become cancerous, every one of these safety mechanisms must fail.

3. Cancer begins in genes. Genes contain the instructions to make proteins, which determine the function of each cell, and ultimately, the function of the entire body. In a cancerous cell, permanent gene alterations, or mutations , cause the cell to malfunction. For a cell to become cancerous, usually three to seven different mutations must occur in a single cell. These genetic mutations may take many years to accumulate, but the convergence of mutations enables the cell to become cancerous.

4. Benign Tumor Benign tumors are not cancerous. They can usually be removed  They do not come back in most cases  They do not spread to other parts of the body and the cells do not invade other tissues There growth is not that fast. CLASSIFICATION OF TUMOR Malignant Tumor Malignant tumors are cancerous. They can invade and damage nearby tissues and organs They can metastasize (cancer cells break away from a malignant tumor and enter the bloodstream or lymphatic system to form secondary tumors in other parts of the body) There growth is very fast.