Shortened Radiotherapy Schedule Has Similar Benefit as Longer Schedule for Low-Risk Prostate Cancer
SAN ANTONIO, TX—Of the more than 220 000 new cases of prostate cancer expected in 2015, the vast majority will be early stage disease at low risk for recurrence. Clinical trial results confirm that these patients can be treated with a shortened (hypofractionated) course of radiotherapy (70 Gy of radiation delivered in 28 fractions over 5.6 weeks) and experience the same level of cancer control as those treated with a conventional course of radiotherapy (73.8 Gy of radiation delivered in 41 fractions over 8.2 weeks).
This trial was conducted by the Radiation Therapy Oncology Group (RTOG), which is now conducting research as NRG Oncology. The trial, RTOG 0415, analyzed data from 1,092 patients with low-risk prostate cancer who were randomized to the hypofractionated schedule (550 patients) or the conventional schedule (542 patients). Its findings were presented at the plenary session of the 2015 American Society for Radiation Oncology (ASTRO) Annual Meeting.
"Given the potential to increase patient convenience and reduce treatment resource utilization significantly using a hypofractionated treatment schedule, we set out to determine if the efficacy of this approach is no worse than that of a conventional schedule in men with low-risk prostate cancer," said the trial's presenter and principal investigator, W. Robert Lee, MD, MEd, MS, a radiation oncologist at Duke University.
Lee pointed out that from a curative perspective the study results should make practitioners feel comfortable that the shorter radiotherapy course is as effective as a conventional course.
"The study results are directly analogous to the breast cancer story in which shorter courses of radiotherapy work as well," said Lee.
At a median patient follow-up of 5.8 years, 185 disease-free survival events (the primary end point) had occurred (86 in the hypofractionated schedule arm; 99 in the conventional schedule arm). Mild side effects (grade 2) were slightly higher in patients assigned to the hypofractionated arm, but more severe, late grade 3 gastrointestinal (GI) and genitourinary (GU) events were no different (GI, 4.1% [70 Gy] vs. 2.4% [73.8 Gy]; GU, 3.5% [70 Gy] vs. 2.1% [73.8 Gy]).
Lee emphasized that these toxicities are physician-reported results, which do not always reflect the patients' experiences accurately. To answer the important question regarding what patients thought about their treatment, in the future, the investigators will analyze patient-reported quality of life data collected during the study. Next steps also include the evaluation of economic data to assess resource savings.
"These results are another example of NRG Oncology's exemplary work in advancing the treatment of men with prostate cancer," said Walter J. Curran Jr, MD, an NRG Oncology Group Chairman and executive director of the Winship Cancer Institute of Emory University in Atlanta, Georgia.
"Congratulations to the research team and participating sites for enrolling patients and concluding the study ahead of schedule. This performance demonstrates the importance that the radiation oncology community places on learning whether a hypofractionated radiation schedule can both increase patient convenience and save health care resources."