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