The interim results of two trials by the researchers in Nagoya, Japan, which aims to assess the efficacy and safety of image-guided proton therapy (IGPT) for either medically inoperable or operable stage I NSCLC. Fifty-five patients (IA in 33 patients and IB in 22 patients; inoperable in 21 patients and operable in 34 patients) were treated with proton for peripherally located tumors 66 Gy (RBE)) in 10 fractions (n = 49) and centrally located tumors 72.6 Gy(RBE) in 22 fractions (n = 6).

The study reported the 3-year overall survival, progression-free survival, and local control rates of 87%, 74%, and 96%. Grade 2 toxicities observed were radiation pneumonitis in 5 patients (9%), rib fracture in 2 (4%), and chest wall pain in 5 (9%). There were no grade 3 or higher acute or late toxicities. The conclusion is that IGPT appears to be effective and well tolerated for all patients with stage I NSCLC.