Proton beam therapy for muscle-invasive bladder cancer: A systematic review and analysis with Proton-Net, a multicenter prospective patient registry database

• Published in: Journal of radiation research 2023-06, Vol.64 (Supplement_1), p.i49-i58
• Main Authors: Araya, Masayuki, Ishikawa, Hitoshi, Nishioka, Kentaro, Maruo, Kazushi, Asakura, Hirofumi, Iizumi, Takashi, Takagi, Masaru, Murakami, Masao, Azuma, Haruhito, Obara, Wataru, Aoyama, Hidefumi, Sakurai, Hideyuki
• Format: Article
• Language: English
• Subjects: Humans; Multicenter Studies as Topic; Muscles; Proton Therapy - adverse effects; Protons; Registries; Supp Pbt; Urinary Bladder Neoplasms - radiotherapy
• ISSN: 0449-3060; 1349-9157
• DOI: 10.1093/jrr/rrad027

To assess the safety and efficacy of proton beam therapy (PBT) for muscle-invasive bladder cancer (MIBC), we examined the outcomes of 36 patients with MIBC (cT2-4aN0M0) who were enrolled in the Proton-Net prospective registry study and received PBT with concurrent chemotherapy from May 2016 to June 2018. PBT was also compared with X-ray chemoradiotherapy in a systematic review (X-ray (photon) radiotherapy). The radiotherapy consisted of 40–41.4 Gy (relative biological effectiveness (RBE) delivered in 20–23 fractions to the pelvic cavity or the entire bladder using X-rays or proton beams, followed by a boost of 19.8–36.3 Gy (RBE) delivered in 10–14 fractions to all tumor sites in the bladder. Concurrently, radiotherapy was given with intra-arterial or systemic chemotherapy of cisplatin alone or in combination with methotrexate or gemcitabine. Overall survival (OS), progression-free survival (PFS) and local control (LC) rates were 90.8, 71.4 and 84.6%, respectively, after 3 years. Only one case (2.8%) experienced a treatment-related late adverse event of Grade 3 urinary tract obstruction, and no severe gastrointestinal adverse events occurred. According to the findings of the systematic review, the 3-year outcomes of XRT were 57–84.8% in OS, 39–78% in PFS and 51–68% in LC. The weighted mean frequency of adverse events of Grade 3 or higher in the gastrointestinal and genitourinary systems was 6.2 and 2.2%, respectively. More data from long-term follow-up will provide us with the appropriate use of PBT and validate its efficacy for MIBC.