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From the Winter 2017 Quest
Intensity-modulated radiation therapy (IMRT) shapes radiation beams to tumors, thus reducing the amount of radiation that affects healthy tissue. Results from a long-term clinical trial in the UK found that IMRT improved outcomes for prostate cancer patients.

The trial tested whether IMRT could be used to treat the lymph nodes of the pelvis, where prostate cancer commonly spreads. The study included 477 patients, many of whom were thought to have “incurable” cancer at the start of the trial due to lack of treatment options. Previously, it was considered too risky to treat a patient’s pelvis with radiation due to the risk of severe bowel side effects. The patients also received longcourse androgen-deprivation therapy.

The study showed positive results using IMRT to help stop the spread of prostate cancer. Five years after treatment with IMRT, 71% of patients in the study were still alive and free of prostate cancer. At 8.5 years of average follow-up, overall survival was 87%. In addition, side effects were manageable. Between 8-16% of patients had bowel or bladder toxicity.

Because IMRT is precisely shaped to the tumor and avoids surrounding healthy tissue, clinicians can increase the amount of radiation targeting cancer cells. This is called hypofractionated radiation therapy, in which the patient has fewer radiation treatments at a higher dose.

The trial was led by researchers at The Institute of Cancer Research (ICR) in London, where the IMRT technique was pioneered. Future studies will need to show increased efficiency to offset the small increase in bowel side effects compared with prostate-only IMRT.

"This technique has already proven to be a game changer for men with prostate cancer and the work done here has already been carried forward into later-stage phase II and phase III trials. I’m excited to see this treatment become available to every man with prostate cancer who could benefit from it."
– Study leader Professor David Dearnaley, Professor of Uro-Oncology at the ICR, and Consultant Clinical Oncologist at The Royal Marsden NHS Foundation Trust

Int J Radiat Oncol Biol Phys. 2017 Aug 2. pii: S0360- 3016(17)33655-6. doi: 10.1016/j.ijrobp.2017. 07.041.
[Epub ahead of print]



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