Development and current status of proton therapy for lung cancer in Korea

The aim of this study was to examine the current status of proton therapy in Korea and to review the dosimetric benefits of proton beam therapy (PBT) over intensity-modulated radiotherapy (IMRT) for lung cancer treatment. Data from patients treated between March 2007 and February 2011 in Korea using proton therapy were analyzed retrospectively. For comparison, IMRT and PBT in the scattering mode were planned for lung cancer patients. Dosimetric benefits and organ-specific radiation-induced cancer risks were based on comparisons of dose volume histograms (DVH) and secondary radiation doses, respectively. On average, the doses delivered by PBT to the lung, esophagus and spinal cord were 17.4%, 2.5% and 43.6% of the prescription dose, respectively, which were lower than the doses delivered by IMRT (31.5%, 11.8% and 45.3%, respectively). Although the average doses delivered by PBT to the lung and spinal cord were significantly lower than those by IMRT, these differences were reduced in the esophagus. While the average secondary dose from PBT (measured at 20-50 cm from the isocenter) was 1.33-0.86 mSv/Gy, the average secondary dose from IMRT was 3.3-1.0 mSv/Gy. Compared with IMRT techniques, PBT showed improvements in most dosimetric parameters for lung cancer patients, with lower secondary radiation doses.