Fig 4.

(A) Cumulative incidence of radiation pneumonitis (RP) and local failure (LF) among patients who were randomly assigned and treated according to time of enrollment (early indicates enrollment before the midpoint of the trial [September 27, 2011; median follow-up, 29 months]; later indicates enrollment after the midpoint [median follow-up, 23 months]). Patients in the later group had lower rates of RP and LF. Similar results were found when patients were analyzed by intention to treat or by treatment received (data not shown). (B) Cumulative incidence of RP among patients who were randomly assigned and treated according to time of enrollment. In the intensity-modulated (photon) therapy (IMRT) group, RP occurred in both the early and the later groups; in the passive scattering proton therapy (PSPT) group, RP occurred only in the early group. The results suggest the existence of a learning curve for the delivery of PSPT, with corresponding improvements in PSPT over the course of the trial.