What is Radiotherapy

Radiotherapy has been used in cancer medicine for more than a century. Thanks to decades of research to refine, improve and innovate the treatment, it’s become an incredibly sophisticated and precise technique. In England alone, around 134,000 courses of radiotherapy are given each year.

The history of Radiotherapy

In November 1895 German physicist Wilhelm Rontgen was experimenting with the effects of electricity on gases. 

Rontgen showed that the mysterious new type of radiation he had discovered could travel through certain substances, such as flesh, but was blocked by others, like bones.

This discovery soon ushered a new era of medical imaging, known as radiology, helping doctors identify fractures and other previously invisible maladies. It was during this surge of worldwide interest into x-rays that scientists made another crucial observation: x-rays could damage the skin if used repeatedly. This prompted scientists to wonder whether they could take advantage of this effect to treat disease, including cancer.

Thanks to the legendary scientific duo Marie and Pierre Curie, another type of radiation joined the medical scene: radium. Realising the potential of this new and exciting treatment, in the 1920s  large sums of money were invested to buy radium for research, starting with the treatment of cervical cancer.

Scientists then continued to carry out pioneering research on radiotherapy, working out how to measure doses and showing how cells respond to radiation. Ultimately, this work laid the foundations for modern radiotherapy, which has dramatically improved since its inception.

 

How does Radiotherapy work?

Radiotherapy works by aiming a high dose of radiation towards a person’s tumour, which damages cells’ fragile DNA – the code of instructions that cells need to survive and do their job.

This can happen in two ways. The radiation can directly damage the DNA by causing breaks along the strands of genetic material, and it can also trigger the formation of very reactive molecules that themselves can be damaging. Unable to cope with this assault to their lifeline, ultimately the cancer cells die.

Since the radiation has to travel through healthy tissues to reach its target, non-cancerous cells may too become damaged by the treatment. Cells have their own tools to fix damage to DNA as it arises, but in cancer cells these are often faulty. So while healthy cells are usually able to stitch their DNA back together and avoid the fatal consequences of the radiation, cancer cells can’t.

That’s why radiotherapy is given to patients across a number of sessions that are spread out over time – these gaps allow the healthy cells to recover. Any harm to healthy tissues is a potential risk though and can lead to side effects. Reducing this risk is crucial to making the treatment kinder for patients, and why modern radiotherapy techniques aim to minimise this collateral damage while also maximising the dose that the tumour gets.

 

Types of Radiotherapy

Although there are many types, broadly radiotherapy is given in 2 ways, from either outside the body (external radiotherapy) or inside (internal radiotherapy). Not everyone has radiotherapy as part of their treatment, but which one is used depends on the type of tumour and where it is in the body.

For example, a type of internal radiotherapy called radioactive iodine therapy is a very effective treatment for patients with thyroid cancer. The radioactive iodine is given as a drink or in a pill and is then taken up by the thyroid cancer cells, but not healthy cells, and hence has few side effects. This is known as radioactive liquid therapy and is one of two main types of internal radiotherapy. The other, called brachytherapy, involves placing a radioactive implant next to the tumour, such as tiny metal pellets or wires.

Although internal radiotherapy works well for certain cancers, external radiotherapy is the most common type used. Different kinds of radiation are used here, usually x-rays but sometimes tiny particles like protons which are found in the hearts of atoms. The radiation is hurled toward the tumour in beams ejected from a highly sophisticated machine, most commonly one called a linear accelerator.

Rather than relying on a degree of guesswork like in the very early days of radiotherapy, today doctors take very detailed images of patients’ tumours and their surroundings using techniques like CT or MRI scans. This helps doctors plan the treatment very precisely in 3D, so the tumour bears the brunt of the blow while its neighbouring healthy tissues are spared as much as possible.

There are also a variety of other tricks to make the treatment more accurate, such as aiming the beams from a number of angles so that they can closely shape the tumour, or switching up their intensity.

Click here to view a video on what it is like having Prostate Radiotherapy. A film for patients: https://youtu.be/YzKLFzjqJnI

Source: CRUK 2017