External radiotherapy

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External radiotherapy aims high-energy X-ray beams, electrons or particle beams, such as protons, at the cancer from outside the body, and is given as a series of short and daily treatments. External radiotherapy can be administered after surgery, or before surgery with the intent of reducing the size of the tumor to make its surgical removal easier. It can also be used alone (without surgery) as the main treatment for cancer, or to relieve symptoms caused by metastases or massive tumors.