Radiotherapy is one of the oldest forms of cancer treatment that started being implemented soon after X-rays were first discovered by Wilhelm Conrad Roentgen in 1896. The reason it is so heavily used to this day is because radiotherapy is a reliable and effective form of cancer treatment recommended for a large number of cancer patients: as per figures provided by the CRUK⁽¹⁾, nearly one third of patients diagnosed with cancer (27%) received curative or palliative radiotherapy as part of their primary cancer treatment.

Figure 1. A linear accelerator (linac) used for treating patients with radiotherapy at the Northern Ireland Cancer Centre.

Radiotherapy kills cancer cells using  ionising radiation to damage their DNA. Radiotherapy is most commonly delivered using external beams of high energy X-rays produced using linear accelerators (linacs) shown in Figure 1.

A linac is a type of particle accelerator that is used to generate X-rays. The X-rays are generated within a rotating gantry that can move around the patient whilst they are lying on a couch. The X-rays pass through collimators that shape the beams to the shape of the tumours. Before radiotherapy is delivered, a portal imaging device is used to ensure that the patient and the tumour are in the correct position for treatment. This reduces the risk of causing damages to normal tissues that may be surrounding the tumour. Different radiotherapy techniques can be used depending on the type and locations of tumours in the body such as stereotactic radiotherapy or using charged particles such as proton beam therapy.

Figure 2. A scan showing the position of radioactive seeds in the prosate gland during brachytherapy for prostate cancer.

The type of radiotherapy that a patient receives depends on several different factors such as the type of tumour, its location within the body relative to surrounding normal tissues, the general health of the patient and whether any other treatments have been given. Radiotherapy may be given as the primary treatment but can also be given to shrink tumours before surgery (neoadjuvant), after surgery (adjuvant) and often in combination with chemotherapy or other drugs.

Radiotherapy can also be delivered to the body internally. This can be done by implanting radioactive sources into the body in a treatment known as brachytherapy. This is a particularly effective form of treatment for some prostate cancer patients. Figure 2 shows the position of radioactive seeds (green) into the prostate gland with bladder and rectum being exposed to low levels of radiation (light blue line).

Other forms of internal radiotherapy involve the injection of radioactive drugs in to the body known as radionuclides. Radionuclides are unstable and release radiation as they decay, which will cause damage to tumour cells. An example of a radionuclide in Radium-223. This is also used to treat prostate cancer patients whose disease has progressed to the bones. Research has being conducted in Belfast to better understand how Radium-223 acts to kill cancer cells and when best to treat patients as part of the ADRRAD trial (Prof Joe O’Sullivan).

Figure 3. A dose of Radium-223 given to a patient treat at the Northern Ireland Cancer Centre
as part of the ADRRAD trial in prostate cancer. 

Despite the success of radiotherapy, treatments can also be harmful to normal tissues that lie very close to tumours. Research within the PGJCCE aims to better understanding the effects or radiotherapy in non-cancer cells and how best to minimise the potential adverse effects of radiotherapy. This is particularly important as the number of new cancer patients that will require at least one course of radiotherapy continues to increase, highlighting the need for well supported, high quality radiotherapy services⁽²⁾. Also, as patients are living longer after treatment, it is important that they can enjoy a high quality of life.

Within the Patrick G. Johnston Centre, Radiotherapy research is organised through the Advanced Radiotherapy Group which brings together a multidisciplinary team of clinicians, physicists, radiation biologists, radiographers and physiologists. The aim of this group is to develop new and advanced radiation treatments encompassing basic laboratory research, pre-clinical studies and clinical delivery.

Sources

1. National Cancer Registration & Analysis Service and Cancer Research UK: "Chemotherapy, Radiotherapy and Tumour Resections in England: 2013-2014" workbook(link is external). London: NCRAS; 2017.
2. Borras et al, How many new cancer patients in Europe will require radiotherapy by 2025? An ESTRO-HERO analysis Radiother Oncol. 2016 Apr;119(1):5-11.

Content provided by: Doctors Cristina Branco and Karl Butterworth.