A highly precise type of radiotherapy called intensity-modulated radiation therapy (IMRT) may be a safer form of treating lymph nodes in patients with prostate cancer, a clinical trial report suggests.
Radiation to pelvic lymph nodes in patients whose cancer has not yet spread is controversial as the treatment may have toxic effects involving the gut and bladder. But the study, published in the International Journal of Radiation Oncology Biology Physics, suggests that if radiation to surrounding tissue is minimized, the method can significantly improve outcomes.
To test the new radiotherapy method, researchers at The Institute of Cancer Research (ICR) in London, and The Royal Marsden NHS Foundation Trust in the U.K., recruited 447 patients with advanced prostate cancer that had not yet spread.
The patients were split into five groups receiving varying doses and a different number of radiotherapy sessions. The study compared a traditional schedule to a so-called hypofractionation approach in which patients receive larger doses during fewer treatment sessions, according to the report, “Phase 1/2 Dose-Escalation Study of the Use of Intensity Modulated Radiation Therapy to Treat the Prostate and Pelvic Nodes in Patients With Prostate Cancer.”
Although patients received radiation to the pelvic area, toxicity was manageable, researchers said. Between 8% and 16% of patients experienced bowel or bladder side effects.
Survival rates were high in all groups, with 87% of patients still alive at five years. Only 8% of the studied patients died of prostate cancer. The results show that this treatment prevented further spread of cancer to the lymph nodes.
“Our trial was one of the first of this revolutionary radiotherapy technique, which was pioneered by colleagues here at the ICR and The Royal Marsden. These long-term results demonstrate that using IMRT to target the pelvic lymph nodes is safe and effective for men with prostate cancer,” David Dearnaley, a professor of uro-oncology at the ICR and a consultant clinical oncologist at The Royal Marsden, who led the study, said in a press release.
The research team had earlier tested IMRT in a clinical trial where men received radiation to either the prostate alone or the prostate and pelvic lymph nodes. The method adapts the radiation to the three-dimensional structure of a tumor, thereby sparing healthy tissue and minimizing side effects.
The current study suggested that the IMRT method can also be safely used in a hypofractionated manner, a finding that researchers will now explore in further clinical trials aiming to determine if the benefits of lymph node IMRT outweigh the risks. If they do, researchers also will set out to determine who may best benefit from the treatment.
“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,” Dearnaley said.
“Radiotherapy is often seen as perhaps old-fashioned and crude compared with other cancer treatments — but nothing could be further from the truth. Radiotherapy today has been enhanced far beyond recognition since its first use over a century ago, and is now a highly precise, incredibly sophisticated treatment, said Paul Workman, chief executive of the ICR.
“It’s great to see this long-term evidence of the degree to which precision radiotherapy has transformed outcomes for men with prostate cancer,” Workman added.