Study: Shorter Radiotherapy Schedule OK for Localized Prostate Cancer

Disease-free survival rates were similar for groups receiving 8.2 weeks of conventional versus 5.6 weeks of hypofractionated radiotherapy.
Disease-free survival rates were similar for groups receiving 8.2 weeks of conventional versus 5.6 weeks of hypofractionated radiotherapy.

For patients with early-stage prostate cancer (PCa) treated with external beam radiation therapy, a shortened schedule of 5.6 weeks offers cancer control similar to that of an 8-week schedule, a new study finds. Minor side effects increased with hypofractionation, however.

“This study has implications for public policy,” lead researcher W. Robert Lee, MD, professor at Duke University Medical Center in Durham, NC, stated in a press release. “Because the shorter regimen has advantages such as greater patient convenience and lower costs, it's important to establishing whether we can cure as many patients with the shorter regimen.”

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Dr Lee and his team randomly assigned 1,092 men with low-risk PCa to receive either conventional radiotherapy (C-RT) of 73.8 Gy in 41 fractions over 8.2 weeks or hypofractionated radiotherapy (H-RT) of 70 Gy in 28 fractions over 5.6 weeks. Patients who had prior radiotherapy, definitive surgery, bilateral orchiectomy, chemotherapy, or cryosurgery were excluded. Androgen deprivation was not allowed, except as salvage therapy.

Estimated 5-year disease-free survival (DFS) was 85.3% for C-RT patients and 86.3% for H-RT patients, according to results published online in the Journal of Clinical Oncology.  The findings established the noninferiority of H-RT, which the investigators defined as a predefined hazard.

Surprisingly, late gastrointestinal and genitourinary adverse events (AEs) increased by 31%–59% among H-RT patients. There were no differences in severe AEs. Dr Lee and colleagues plan to explore whether the use of intensity-modulated radiotherapy affected late toxicity, compared with 3-dimensional conformal radiotherapy.

Among the study's limitations, the investigators acknowledged that many men with low-risk PCa may not require treatment and can opt for active surveillance. For those who choose definitive treatment, however, these results are helpful. The findings do not extend to men who progress from low-risk disease after a period of active surveillance.

Sources

  1. Lee WR, Dignam JJ, Amin MB, et al. Randomized Phase III Noninferiority Study Comparing Two Radiotherapy Fractionation Schedules in Patients With Low-Risk Prostate Cancer. J Clin Oncol. doi:10.1200/jco.2016.67.0448.
  2. Shorter, Intensive Radiation Can be Recommended in Early Prostate Cancer [press release] Duke University Medical Center. April 4, 2016.
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