Impact of Treating Physician on Radiotherapy Related Severe Toxicities in Men with Prostate Cancer.

ABSTRACT Background The impact of treating physician on radiotherapy-related toxicity is unclear. We carried out a secondary analysis of a randomized controlled study to determine if the risk of radiotherapy-related late toxicities in prostate cancer (PCa) patients varies depending on the treating radiation oncologist. Patients and Methods This is a secondary analysis of a phase III randomized controlled study in which PCa patients with Gleason score ≤7, clinical stage T1b-T3a and prostate-specific antigen 0. Commenges-Andersen test was used for p-value estimation. Results Overall, 426 patients were treated by 9 radiation oncologists. On log-rank test, there was a significant difference in the cumulative incidence of overall grade ≥3 toxicities (p=0.001) and grade ≥3 gastrointestinal (p=0.01) among the physician-based clusters. The frailty variance for overall late grade ≥3 toxicity was 0.31 (95% CI: 0.02-1.39)(p=0.01). The frailty variance for the grade ≥3 gastrointestinal and genitourinary toxicity was 0.84 (95% CI: 0.00-4.20)(p=0.11) and 0.11 (95% CI: 0.00-1.13)(p=0.31), respectively. Conclusions In our study, the hazard of overall radiotherapy-related late grade ≥3 toxicity varied significantly depending on treating radiation oncologist. Further studies are required to explore the underlying processes that lead to such variations in clinical trials involving radiotherapy in prostate cancer.