A study published in Journal of Thoracic Oncology compares the toxicity profiles and clinical outcomes after Intensity-Modulated Proton Therapy (IMPT) vs. versus Passive Scattering Proton Therapy (PSPT) for locally advanced non-small cell lung cancer.
This is a non-randomized, comparative study of two independent cohorts with LA-NSCLC treated with concurrent chemotherapy and proton beam therapy. Toxicity and outcomes were prospectively collected as part of a clinical trial or prospective registry.
Of 139 patients, 86 received PSPT and 53 IMPT. IMPT delivered lower mean radiation doses to the lungs, heart and esophagus. Consequently, the IMPT cohort had lower rates of grade more than or equal to 3 pulmonary and cardiac toxicities. Six PSPT patients and 0 IMPT patients experienced grade 4 or 5 toxicity.
Lower rates of pulmonary and cardiac toxicities were observed in the IMPT cohort even after propensity score matching for baseline imbalances. There was also a trend toward longer median overall survival in the IMPT group. No difference was found in 3-year rates of local, local-regional and distant recurrences.
It was concluded that IMPT is associated with lower radiation doses to the lung, heart and esophagus, and lower rates of grade more than or equal to 3 cardiopulmonary toxicity; additional clinical studies will be needed to assess potential differences in survival between the two techniques.