Early scans reveal risk of toxicity from prostate radiotherapy

Early scans reveal risk of toxicity from prostate radiotherapy

A study suggests that daily scans taken during radiation therapy for prostate cancer could be repurposed to guide changes in treatment, thereby reducing the risk of side effects.

Using AI, scientists found that images originally taken to position patients for radiation therapy can also detect changes associated with future rectal bleeding as early as a week after treatment begins.

Monitoring these early changes could help doctors decide when to adjust radiation therapy to limit side effects while maintaining cancer control, experts say.

Radiation therapy is an effective treatment for prostate cancer, but it can cause side effects such as rectal bleeding. This happens when nearby healthy tissue, such as the rectum, receives a small amount of radiation due to its proximity to the prostate.

With adaptive radiation therapy, treatment plans are updated regularly to respond to changes in the patient's anatomy, rather than using the same plan for the entire treatment period. Decisions to change radiation therapy currently do not take into account subtle changes and patterns in the tissue – so-called radiomic features.

Scientists at the University of Edinburgh examined daily imaging data from 187 patients treated with prostate radiotherapy and used machine learning tools to identify associations between radiomic features and the development of rectal bleeding within two years of therapy.

Patterns observed on individual scans one week after starting treatment strongly predicted subsequent rectal bleeding. It turned out that combining data from the first three weeks of scans provided the most reliable prediction.

The findings suggest that tracking radiomic features could provide a valuable early window for interventions that could improve or personalize radiation therapy, experts say.

The approach could one day be integrated into routine treatment planning and monitoring to help doctors decide when and how to adjust prostate radiation therapy plans, researchers suggest. However, they caution that this will likely take many years and the results should be confirmed by a larger study.

The study, funded by Prostate Cancer UK, is published in the journalPhysics and imaging in radiation oncology: The research team included scientists from the University of Cambridge and Christie NHS Foundation Trust.

The key finding here is that imaging early in treatment provides quantitative information about subsequent risk of toxicity, long before symptoms appear. This supports the idea that predictive biomarkers for adaptive radiotherapy may not require new scans or technologies, just better use of the data we are already collecting.”

Dr. Zhuolin Yang, research fellow at the Institute of Genetics and Cancer, University of Edinburgh

Professor Bill Nailon, clinical scientist at Edinburgh Cancer Centre, said: "This study provides proof of concept that imaging collected for the beam facility could support future adaptive workflows. Future studies and automation will be essential before approaches such as this can be integrated into clinical decision-making."

Dr. Hayley Luxton, Head of Research Impact at Prostate Cancer UK, said: "Radiotherapy is a very common treatment to cure prostate cancer. The natural movement of the prostate and surrounding organs during treatment, while very effective, can cause damage to surrounding areas and cause bleeding and other side effects which can have a significant impact on men's lives."

"We know that treatments need to be gentler, which is why, in collaboration with Movember and the Garfield Weston Foundation, we funded this research to find out which men are most likely to experience these side effects and change their treatment plan early to avoid these problems without compromising the effect on the cancer itself."

“While further research is still needed in larger groups of men, this represents a major step forward in personalizing radiotherapy to make it gentler and better for more men who need it.”

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