Saturday, August 27, 2016

Proton has no toxicity advantage over IMRT in case-matched analysis

Proponents of proton therapy have touted its theoretical healthy tissue-sparing effects.There has never been a randomized clinical trial comparing proton (PBT) to photon (IMRT) treatment that would demonstrate whether such an effect in fact exists in clinical practice. Previous retrospective cohort and database studies have failed to demonstrate significant differences in urinary and rectal toxicity. Fang et al at UOP published a case-matched study of PBT vs IMRT toxicity.

  • 91 case-matched pairs were identified from a pool of 394 patients treated from 2010-2012
  • They were matched by risk group, age, and prior gastrointestinal and genitourinary disorders.
  • Both sets of men received 79.2 Gy of radiation, whether by proton or photon
  • Bladder and rectal dosimetry were significantly better for PBT vs IMRT
  • Median follow-up was  47 months (range, 5-65 months) for patients who received IMRT and 29 months (range, 5-50 months) for those who received PBT. 

 The results were: no significant differences in
  • Grade≥2 acute urinary toxicity 
  • Grade≥2 acute rectal toxicity 
  • Grade≥2 late urinary toxicity 
  • Grade≥2 late rectal toxicity 
  • They did not measure differences that may have occurred in sexual function.

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