The dosimetric advantages of PBT over photon radiotherapy may be clear but the translation of this benefit into clinically meaningful reductions in toxicities and improved quality-of-life (QoL) needs to be determined. This systematic review examined the methodology used in clinical trials that reported PBT benefits. Out of the 219 studies included, prospective studies comprised 89/219 (41%), and of these, the number of randomised phase II and III trials were 5/89 (6%) and 3/89 (3%) respectively.

Of all the phase II and III trials, 18/24 (75%) were conducted at a single PBT centre. Over one-third of authors recommended an increase in length of follow up. Research design and/or findings were poorly reported in 74/89 (83%) of prospective studies. Patient reported outcomes were assessed in only 19/89 (21%) of prospective studies.