Table 5. Results of PBT for retroperitoneal tumors.

Reference & date	Number of patients	Tumor characteristics	PBT dose, fractionation, Technique	Chemotherapy	Median follow-up (months)	Survival outcomes	Toxicity
Yoon et al., 2010 (60)	28 (8 recurrent). PBT (n=10), IMRT (n=11), both (n=7). PBT preferentially used with large tumors adjacent to liver, kidneys, bowel	14/28 (50%) liposarcoma; 6/28 (21%) leiomyosarcoma; Remainder other sarcoma: 21/28 (75%) treated neoadjuvantly	Median dose 50 Gy or CGE in 28 fractions for IMRT/PBT, anterior/posterior obliques, 12/28 (43%) received IOERT, median 11 Gy	3/28 (11%); adjuvant (n=1) or neoadjuvant (n=2)	33	3 y LC 90%, 3 y RFS 90% (nonrecurrent); 3 y LC 63%, 3 y RFS 30% (recurrent); 3 y DRFS 78%, 3 y DSS 87%, 3 y OS 87%	Ureteral stricture (1/28, 4%, received IMRT/PBT/IOERT), hemorrhage of unknown origin (1/28, 4%, PBT only), enterocutaneous fistula (1/28, 4%, IMRT only), infected seroma (1/28, 4%, IMRT + IOERT)
Schneider et al., 2013 (61)	31	25/31 (81%) chordoma; 5/31 (16%) sarcoma; 1/31 (3%) meningioma	Mean 72.3 CGE in 40 fractions, PA or single posterior oblique	None	59	3 y LC 68%, 5 y LC 52%; 3 y OS 84%, 5 y OS 72%	No grade 2 + toxicities

PBT, proton beam radiotherapy; IMRT, intensity-modulated radiotherapy; IOERT, intraoperative electron radiotherapy; Gy, Gray; CGE, Cobalt Gray equivalent; LC, local control; RFS, recurrence-free survival; DRFS, distant recurrence-free survival; DSS, disease-specific survival; OS, overall survival; PA, posteroanterior.