Hypofractionated, conventional radiation therapy show similar long-term efficacy in prostate cancer
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Moderate hypofractionated intensity-modulated radiation therapy produced long-term outcomes similar to those of conventionally fractionated IMRT among men with localized prostate cancer, according to a 10-year update of a randomized phase 3 trial.
The findings mirrored previously published 5-year follow-up data that showed hypofractionated IMRT (H-IMRT) and conventionally fractionated IMRT (C-IMRT) were equally effective for this patient population.
As Healio previously reported, a guideline published jointly in 2018 by the American Society for Radiation Oncology, ASCO and American Urological Association recommended H-IMRT — administered at a higher dose over less time than C-IMRT — as the standard of care for men with localized prostate cancer.
“The take-home message is that moderately hypofractionated IMRT should be the standard of care for most men with localized prostate cancer receiving radiation,” Eric M. Horwitz, MD, FABS, FASTRO, chair of radiation oncology at Fox Chase Cancer Center and senior author of the study, told Healio. “Long-term data from a national cancer center supports this treatment as safe, effective and more convenient for our patients.”
Horowitz said it is no surprise that the 10-year findings mirror those of 5 years ago.
“What they demonstrate is the durability of this treatment approach,” he said.
Researchers in the trial randomly assigned 303 men with localized prostate cancer to either C-IMRT (76 Gy in 38 fractions at 2 Gy per fraction, n = 152) or H-IMRT (70.2 Gy in 26 fractions at 2.7 Gy per fraction, n = 151) between June 2002 and May 2006. The groups were evenly matched for clinical characteristics except race, with a higher proportion of black men in the C-IMRT group (17.8% vs. 7.3%; P = .02).
Twenty-eight men (9.2%) had low-risk disease, 189 (62.4%) had intermediate-risk disease and 86 (28.4%) had high-risk disease, according to updated National Comprehensive Cancer Network risk classification. Men with high-risk prostate cancer were prescribed 24 months of androgen deprivation therapy in addition to radiation therapy and also underwent lymph node irradiation, whereas those with intermediate-risk disease could receive 4 months of ADT at the physician’s discretion. Median ADT use did not differ between the groups.
Cumulative incidence of biochemical and/or clinical disease failure (BCDF) served as the study's primary endpoint.
Median follow-up was 122.9 months (range, 7-181).
Results showed 10-year cumulative incidence of BCDF of 25.9% in the C-IMRT group compared with 30.6% in the H-IMRT group (HR = 1.31; 95% CI, 0.82-2.11).
The C-IMRT and H-IMRT groups had similar 10-year cumulative incidence of biochemical failure (21.1% vs. 25.4%) and all-cause mortality (24.4% vs. 33.2%). Researchers reported higher 10-year cumulative incidence of distant metastases in the H-IMRT group compared with the C-IMRT group (14.3% vs. 6.4%; rate difference, 7.8%; 95% CI, 0.7-15.1).
These results are consistent with the 5-year findings and show no statistically significant differences in 10-year rates of BCDF, local recurrence or overall mortality rates between the two treatment groups.
“In 2001, the common thought was that hypofractionation would be superior to conventional hypofractionation. This, in fact, was not the case in our study,” Horwitz told Healio. “Over time, we recognized that hypofractionation wouldn’t be better, but that it was equally effective and safe — with minimal short-term and long-term complications — and far more convenient for our patients. This is now recognized as the benefit of hypofractionated treatment.
“Our patients are not sacrificing effectiveness for convenience,” Horwitz said. “They can be well-treated quickly with minimal disruption in their lives.”
For more information:
Eric M. Horwitz, MD, can be reached at Department of Radiation Oncology, Fox Chase Cancer Center, 333 Cottman Ave., Philadelphia, PA 19111; email: eric.horwitz@fccc.edu.
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