Hypofractionation of radiation therapy in treatment of localized prostate cancer

Many readers may be interested in reading an editorial just published in the Journal of Clinical Oncology that deals with “hypofractionation” (giving fewer doses of radiation therapy at higher dose levels) in treatment of localized prostate cancer.

The editorial is by Dr. Robert Lee of Duke University School of Medicine in Durham, NC, and is related to a newly published report by Pollack et al. entitled “Hypofractionated radiation in prostate cancer: not superior” that appears in the same issue of the journal.

Specifically, the paper by Pollack et al. is based on a clinical trial in which 303 men with favorable- to high-risk prostate cancer were randomized to one or other of two radiation regimens:

  • 151 men were treated with hypofractionated intensity-modulated radiation therapy (IMRT), receiving a total dose of 70.2 Gy delivered in 26 fractions of 2.7 Gy.
  • Another 152 men were treated with conventional IMRT, and received a total of 76 Gy delivered in 38 fractions of 2 Gy.

The trial results showed that, at a median follow-up of 68.4 months,

  • The 5-year rate of biochemical and/or clinical disease failure was
    • 23.3 percent among men receiving hypofractionated IMRT
    • 21.4 percent among men receiving conventional IMRT
    • This difference was not statistically significant.
  • Patients in the hypofractionated therapy group who had compromised urinary function at baseline had a significant increase in grade 2 or higher late genitourinary toxic effects, compared with patients with normal or mild urinary dysfunction (but his was not observed in patients treated with conventional IMRT).

In his editorial, Lee points out that other trials are ongoing that seek to determine whether hypofractionated IMRT is better, worse, or offers just the same outcomes as conventional IMRT.  He concludes by stating that

If, and it is a big if, the [non-inferiority] trials suggest that moderate hypofractionation is no worse than conventional fractionation, then the burden of proof will be met and, for patient convenience and cost reasons, moderate hypofractionation should be the standard of care.

At the present time, however, there are no definitive data to suggest that hypofractionated IMRT is any better, any worse, or just the same as conventional IMRT. The paper by Pollack et al. has simply shown us that it is probably no worse (except perhaps for those patients who already had a compromised urinary function at baseline).

Pollack’s paper and Lee’s editorial are also discussed in commentary on the Medscape web site.

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