Radiotherapy (a portmanteau of radiation therapy) is an effective and highly-advanced way of treating cancers. In short, radiotherapy involves using cell-killing ionising radiation in order to destroy cancer cells and prevent them from returning.

So what exactly is radiotherapy and how does it work?

Radiotherapy works when cancers are localised. If someone has a cancerous lump in their breast, for example, radiotherapy can be used to target the exact area where the cancer was present and use ionising radiation to kill the cells.

Obviously, doctors will want to target only the cancerous cells and not healthy tissue. The radiation needs to pass through healthy cells such as skin or muscle before it reaches the tumour, however, but impact as little damage on them as possible. For this, numerous smaller beams of radiation are targeted at the area. This means that the smaller beams will do less damage to healthy cells it passes through, but as numerous beams of radiation cross over at the point of the tumour, it is here the radiation is at its strongest.

Ionising radiation will then be used to damage the cells’ DNA, causing them to die or stopping their growth.

Radiotherapy can be used on numerous cancers in very different ways. Some radiotherapy – such as for breast cancer – is undertaken post-operation. This involves treating the area to ensure than any cancer cells not removed with the tumour are killed so they cannot cause a return of the cancer.

Elsewhere, radiotherapy can be used to slow the growth of cancers or reduce them pre-operation. This would be the case if a tumour had gone untreated for long periods of time and has grown to a level that would make removal unsafe. In this instance, radiotherapy can reduce the size of the tumour and make its removal much safer, easier and more effective.