Protons vs IMRT for localized prostate cancer showed no difference in outcome or quality of life. There will be longer f/u and other endpoints studied but the take-home message is that protons are not significantly better than photons.
Patients with localized prostate cancer have several treatment options including external beam radiotherapy with either photons or protons. Proton beam therapy (PBT) has certain dosimetric advantages with the potential to reduce treatment-associated morbidity and improve oncologic outcomes, but it is generally more resource intensive than intensity modulated radiation therapy (IMRT). To address the hypothesis that PBT results in improved patient-reported outcomes (PROs), PARTIQoL (NCT01617161) was conducted as a multi-center phase 3 randomized trial comparing the two modalities.
Patients with intermediate- or low-risk prostate cancer were randomized to PBT or IMRT, without hormonal therapy, stratified for institution, age, rectal spacer use, and fractionation (79.2 Gy/44 fractions vs 70 Gy/28 fractions). Participants were followed longitudinally to assess PROs of bowel, urinary, and sexual function for 60 months (mo) after completion of radiotherapy. Primary endpoint was to compare change from baseline in bowel quality of life (QOL) using the health care software score (range 0-100) at 24 mo. Secondary objectives include comparison of urinary and sexual functions, toxicity, and efficacy endpoints.
Between 06/2012-11/2021, 450 patients from 30 recruiting centers were randomized: PBT (N=226) and IMRT (N=224), of whom 221 and 216 were eligible and started radiation on the respective arms. Median follow-up was 60.3 mo among 424 patients still alive. Median age was 68 yrs (range 46-89), 59% had intermediate-risk disease, 51% received hypofractionation, 48% used a rectal spacer, and 49% of PBT patients were treated with pencil beam scanning. There was no difference between PBT or IMRT in mean change of health care software bowel score at 24 mo (p=0.836), with both arms showing only small, clinically non-meaningful decline from baseline (see Table). Similarly, there was no difference in bowel function at earlier timepoints (3, 6, 9, 12, 18 mo) or later timepoints (36, 48, 60 mo). No differences were observed in other domains (urinary, sexual, hormonal) at any timepoint. There was no difference in progression-free survival (PFS) (93.4% vs 93.7% at 60 mo, HR 1.16 [0.53, 2.57], p=0.706). There was no sustained difference in any QOL domain or PFS between arms in subgroups defined by stratification variables.
This prospective randomized clinical trial shows that patients treated with contemporary radiotherapy for localized prostate cancer achieve excellent QOL with highly effective tumor control, without measurable differences between PBT and IMRT. We continue to monitor participants for longer follow-up and secondary endpoints.
Less radiation is non-inferior, this is for low and intermediate-risk localized prostate cancer patients. Would like input from our radiation oncologists as to whether or not this adoptable?
Will we be replaced by AI? It seems that for radiologists, an AI system was better than the human counterpart in this study looking at prostate cancer diagnostic imaging. I doubt many of us would accept a solely computer-generated report, but this study highlights how AI may help as a supportive tool in the primary diagnostic setting. Of course, prospective validation will be needed.
10-year metastasis-free survival was 71.9% in the short-course ADT group (6 months) and 78% in the long-course ADT group (24 months). So, it seems the longer the duration, the better the outcome. 93% had a Gleason score of 7 or higher.
We know that combination PARP and antiandrogen is better than antiandrogen alone. I have wondered if we need antiancrogen on those patients. This shows that, YES, we do. The combination also was better than PARP inhibitor monotherapy in those patients carrying HRRm.
It might be costly to get the PET scans but helps with prognosis and directing patients to palliative care since positive lesions in all predicts shorter overall survival.
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