What is radiotherapy and how does it work? | Cancer Research UK

Radiotherapy has been used to treat cancer for over a century. It works by aiming intense beams of energy at cancer cells, damaging their DNA. If a cancer cell cannot repair its damaged DNA, it dies. However, radiation also damages nearby healthy cells, which causes side effects.

Most radiotherapy is given from outside the body, usually using x-rays. New experimental techniques are improving accuracy. MRI scans can help track difficult-to-pinpoint tumors, such as lung cancers that move with breathing. Experimental MRI-guided radiotherapy is designed to only fire radiation when the tumor is precisely in its crosshairs. IMRT shapes the radiation beam to match the tumor, reducing damage to healthy tissue. Sabre uses more intense radiation beams for a greater chance of killing tumor cells, meaning fewer hospital trips for patients.

One problem with x-rays is they continue to travel through the body after hitting the tumor, damaging normal cells. Proton beam therapy, a different type of radiation, stops when it hits the tumor, sparing the tissue behind it and helping treat tumors in sensitive locations.

Radiotherapy given from inside the body can precisely kill cancer cells. Thyroid cancer can be treated with a radioactive iodine drink, which is taken up by thyroid cells specifically, resulting in few side effects. Brachytherapy is a surgical technique where a radioactive implant, such as tiny metal pellets or wires, is placed inside the tumor, putting radiation exactly where it's needed.

These different techniques help make radiotherapy more precise, minimizing damage to healthy cells. Through research, this reduces side effects and could speed up recovery time for patients.