Finally, we have Level 1 evidence that proton vs. photon treatment of low-risk/intermediate-risk localized prostate cancer is no different in effectiveness or any quality of life domain (rectal, urinary, or sexual).
This prospective randomized trial, called the PARTIQoL trial, was an enormous undertaking, involving 450 patients from 30 recruiting centers, including 12 proton centers beginning in July 2012. Hormone therapy was not allowed. Patients were stratified on the following parameters:
- risk level (59% intermediate-risk)
- institution
- age (median 68)
- rectal spacer use (45%)
- fractionation -79.2 Gy/44 fractions (49%) or 70 Gy/28 fractions (51%)
- Pencil-beam proton scanning (49%)
After 2 years, there was no difference in rectal domain scores, with both showing minimal declines from baseline.
- There were no differences at earlier timepoints.
- There were no differences at later timepoints up to 5 years of follow-up.
- There were no differences in urinary or sexual domains at any timepoint.
- There were no differences in progression-free survival, which was 93%
- There were no differences in any endpoint of the subgroups defined by any of the stratification variables.
I suspect that many proton centers will have to declare bankruptcy after this, although there is still a use in pediatric tumors.
