National survey on definitive radiotherapy practices for locally advanced non-small cell lung cancer in Japan: JROSG...

This survey was conducted to examine the real-world practice of definitive chemoradiotherapy (CRT) for locally advanced non-small cell lung cancer (LA-NSCLC) in Japan, aiming to standardize treatment, reduce inter-institutional disparities and identify areas for future research. A questionnaire was sent to members of the Japanese Radiation Oncology Study Group through a mailing list, with responses collected between December 15, 2023, and March 14, 2024. Responses from 112 institutions revealed that 81.2% either did not set general upper age limits or established limits at 80 years or older for definitive CRT in LA-NSCLC. The most common absolute contraindications were active interstitial pneumonia (60.7%) and contralateral hilar lymph node metastasis (42.0%). Relative contraindications involved dose-volume indices of the normal lung (70.5%). The most commonly adopted dose-volume indices were lung V20Gy < 30%, lung V5Gy < 60% and mean lung dose <20 Gy, while no definite indices were established for heart V50Gy and mean heart dose in half of the institutions. Additionally, 88.4% of institutions reported using IMRT for LA-NSCLC. Involved-field radiotherapy (IFRT) was adopted regardless of institutional size, and institutions with higher IMRT usage for LA-NSCLC also had higher IFRT adoption rates. In conclusion, this nationwide survey revealed the expanded use of definitive CRT and a growing emphasis on reducing lung dose to mitigate pulmonary toxicities, facilitated by advancements in IMRT and IFRT. Regularly conducting these surveys is essential to monitor evolving treatment strategies.