Proton Therapy for Primary Renal Cell Carcinoma: The First Nationwide Retrospective Study in Japan.

BACKGROUND/AIM This multi-institutional study aimed to investigate the efficacy and feasibility of proton beam therapy (PBT) for renal cell carcinoma (RCC) in Japan. PATIENTS AND METHODS The survival, local control, and toxicities in 22 RCC patients treated between 2001 and 2016 at 6 Japanese PBT institutes were analyzed. RESULTS The 22 patients comprised 20 men and had a median age of 67 (range=42-88) years. The total irradiation dose was 60-79.6 Gy (relative biological effectiveness). Over a median follow-up of 37 months, the 3-year overall and disease-specific survival rates were 95% and 100%, respectively, and no recurrence occurred. No patient experienced grade 3 or higher adverse events. The serum blood urea nitrogen (p=0.25) and creatinine levels (p=0.95) were not significantly affected, although the mean estimated glomerular filtration rate was reduced by 7.1±11.2 ml/min/1.73 m2 Conclusion: Despite the small number of patients, high-dose PBT can control RCC while maintaining their renal function with high probability, and could be and alternative curative therapy especially for inoperable patients.