Radiotherapy for Prostate Cancer

As of August 2023, Prostate Cancer UK reported that over 52,000 men are diagnosed with prostate cancer every year in the UK. Some 30% of these patients will receive radiotherapy as their main course of treatment according to the Institute of Cancer Research.

Radiotherapy involves the use of ionising radiation delivered from an external source, this often takes the form of high energy x-rays that are produced by a linear accelerator. The ionising radiation damages all cells in the body, and cancerous cells are far less able to repair from this damage compared to healthy cells. This results in the death of cancerous cells, and the regeneration of damaged healthy cells when treatment is successful. Radiotherapy can be used in conjunction with surgery or chemotherapy depending on the individual and their disease.

How do we treat at the moment?

Historically, patients who received radiotherapy for localised prostate cancer (cancer that hasn’t spread to other parts of the body) have normally been treated in upwards of 20 fractions, with some patients being treated in over 30 fractions. A fraction is another way to describe an individual treatment session, as fractions of a whole treatment course. Most patients will receive 1 treatment fraction a day, with a break over weekends. For example, patients treated in 37 fractions, a common choice, would have to wait over 7 weeks to complete their treatment. With so many trips to hospital, many patients have shared how difficult this lengthy process can be.

What is the PACE-B trial?

The PACE (Prostate Advances in Comparative Evidence) trial was set up to evaluate the use of hypofractionation in radiotherapy for localised prostate cancer. Hypofractionation refers to reducing the number of treatment fractions a patient will receive, and increasing the dose per treatment to compensate. The PACE-B trial focuses on early stage and localised prostate cancer in patients that haven’t had surgery. Patients were randomised to either conventional radiotherapy (in 39 or 20 fractions) as a control, or hypofractionated radiotherapy (in 5 fractions). On Monday 2nd October 2023, the 5 year findings of PACE-B were presented at the American Society for Radiation Oncology (ASTRO) Annual Meeting.

What did the trial measure?

The primary objective of PACE-B was to compare conventionally fractionated radiotherapy with hypofractionated radiotherapy (greater or fewer treatment sessions) for low risk localised prostate cancer where no surgery was used in the treatment plan. To do this, it compared the likelihood of biochemical failure between the control and the trial groups as an indicator of disease progression. Biochemical failure was defined using PSA, prostate specific antigen. This is a protein present in the blood produced by healthy and cancerous cells in the prostate. When someone has prostate cancer, it is usually accompanied by an elevated level of PSA in their blood. A rising PSA level in the blood after treatment of prostate cancer can indicate that the cancer has returned. Those who do not show an elevated PSA level are deemed to not have disease progression, this would form the basis of conclusions drawn about the trial.

What results did the trial find?

At the 2023 ASTRO Annual Meeting, the 5 year findings of PACE-B were reported. It was found that 95.7% of the trial group had no biochemical failure (marked by elevated PSA levels) in the 5 years after treatment, compared to 94.6% of the control group. This result shows that treating patients with hypofractionated radiotherapy is no worse when compared with conventional, many-fraction radiotherapy. It was also found that side effects were generally low in both groups, with no appreciable difference between them. These results suggest that patients can be treated in fewer fractions with results that are just as good as the current accepted best practice with 20 or more fractions.

What do the results mean for the future?

Radiotherapy is a field that is constantly responsive to innovation and research. Whether it’s new imaging technology to align patients with more accuracy, AI enabled outlining of organs on CT scans used to plan treatment, or changing how we deliver radiation like in the PACE-B trial. These changes do not happen instantly though. Radiotherapy is tightly regulated to ensure patients are always kept safe and treatments are the best that can be offered. The knowledge of the success of hypofractionated treatment for prostate cancer patients will begin to inform changes in how radiotherapy is planned, and may encourage future trials to consider hypofractionation for other radiotherapy. Another study, from Cheung et al in 2023, considered the environmental impacts of hypofractionated radiotherapy. By looking at the energy consumption of treatment machines, PPE usage, and the amount of patient travel, they found that when hypofractionated treatments increased from 17% of their workload to 27%, a reduction of 39% in carbon footprint was observed. This suggests that the benefits of a move to hypofractionated radiotherapy extend beyond just patient experience.

Are you interested in radiotherapy?

Would you like to know more about how you could work in radiotherapy? There are a multitude of roles in radiotherapy, including:

• Therapeutic Radiographer
• Dosimetrist/Clinical Technologist
• Engineer
• Physicist

Clicking on each link takes you to the NHS Healthcare Careers page where you can learn more.

If you’d like to experience what it might be like to work in radiotherapy, you could contact your local hospital and see if they can facilitate a work experience placement.