Short-course hypofractionation noninferior to conventional IMRT
A shorter course of higher doses of radiation produced 5-year outcomes similar to conventional intensity-modulated radiotherapy for patients with intermediate- to high-risk prostate cancer.
Hypofractionated IMRT produced similar results equivalent to conventional IMRT for biochemical failure, any failure or late side effects while shortening the duration of treatment by about 17 days. Alan Pollack, MD, chairman of radiation oncology at the University of Miami Miller School of Medicine, discussed the results of a phase 3 dose-escalation study Monday during a press conference in advance of the 53rd ASTRO Annual Meeting.
"The hypofractionation regimen was found to be as effective as conventional fractionation in terms of preventing PSA from rising," Pollack said. "In general, the side effects were low. There were no differences in bowel or rectal side effects, no difference in the ability to obtain an erection satisfactorily."
A total of 303 men enrolled in the study from 2002 to 2006. Patients were randomly assigned to 76 Gy in conventional 2 Gy fractions (n=152) or 70.2 Gy in 2.7 Gy fractions during 5.1 weeks (n=151), which researchers estimated to be equivalent to 84.4 Gy in 2 Gy fractions.
Researchers observed 20 biochemical failures in the conventional IMRT group (14.4%; 95% CI, 8.8-21.5) vs. 21 (13.9%; 95% CI, 8.4-20.9) in the hypofractionation group. The rate of locoregional failure/distant metastases was 1% in the conventional group vs. 1.3% in the hypofractionation group.
Rate of any failure at 5 years was 15.4% (95% CI, 9.5-22.7) in the conventional group and 15.3% (95% CI, 9.5-22.4) in the hypofractionation group.
Patients in the hypofractionation group experienced slightly more grade-2 genitourinary toxicity than the conventional group (13.8% vs. 8.9%), but grade-2 gastrointestinal toxicities were nearly equal (5.9% vs. 4.1%). The differences were not significant in both cases. Pollock said incidence of late urinary symptoms were significantly higher in the hypofractionation group, but remained less than 10%.
"We did see some increase in urinary side effects; however, the overall rate was rather low," he said.
Researchers observed some evidence that hypofractionation could be associated with improved quality of life, but the issue requires more study, according to Pollack.
For more information:
- Pollack A. #1. To be presented at: 53rd ASTRO Annual Meeting; Oct. 2-6, 2011; Miami Beach
Decreasing the time and the number of treatments patients need not only enhance patient satisfaction, but also has the potential to substantially reduce costs. These results have significant comparative effectiveness implications when one factors in cost.
- Michael L. Steinberg, MD
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