Monday, September 19, 2016

Hypofractionated radiation therapy using IMRT has a clear advantage

I was reticent to write about hypofractionation yet again after writing about it so often in the last year. See this link for my latest summary. In a sea of randomized trials demonstrating that hypofractionated radiation therapy (i.e., it is delivered in fewer treatments or fractions) was no worse in cancer control or in toxicity to conventionally fractionated (40-44 treatments), there was one study, the Dutch HYPRO study, where the toxicity was a bit worse. At the time (see this link), I speculated that that was because they included an older radiation technique called 3D-CRT rather than the IMRT technology that is now prevalent in the US. A new study from MD Anderson suggests that may indeed be the case.

Hoffman et al. presented the patient-reported outcomes of 173 men with localized prostate cancer who were treated at M.D. Anderson in Houston. They were randomized to receive either:
  1. 75.6 Gy in 42 fractions (conventional fractionation) via IMRT
  2. 72 Gy in 30 fractions (hypofractionation) via IMRT
The men filled out questionnaires at baseline, and at 2, 3, 4, & 5 years after treatment. Patients were probed on their urinary, rectal and sexual status. Patient-reported outcomes on validated questionnaires is a more reliable source of toxicity data because it does not rely on the patient volunteering information to the doctor or the doctor assessing or recording that information. Analysis of the two groups showed that:
  • there was no difference with regard to rectal issues (urgency, control, frequency, or bleeding).
  • there was no difference with regard to urinary issues (pain, blood in urine, waking to urinate at night, or leakage)
  • there was no difference with regard to sexual issues (erections firm enough for intercourse)
  • there were no differences at 2, 3, 4, or 5 years.
This should dispel any concerns that completing IMRT in less time may be more toxic. Just as with all forms of radiation, the technology has improved greatly over the years. In the hands of an experienced and careful radiation oncologist, there is no reason that external beam therapy cannot be completed in less time and at lower cost.

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