Abstract

PURPOSE/OBJECTIVE(S): For patients with locally recurrent thoracic tumors or second primaries within previously irradiated volumes, hyperfractionated reirradiation (re-RT) may mitigate late toxicity compared to conventional fractionation, but clinical outcomes have not been extensively studied. We herein report our institutional experience with thoracic hyperfractionated reirradiation.MATERIALS/METHODS: We identified 26 cases among 23 patients treated with re-RT to either primary or metastatic thoracic tumors, 60 Gy in 50 fractions, twice daily over 5 weeks using highly conformal image guided RT with motion management. Nineteen patients had dosimetry data available. The primary outcome was Grade (G2) or higher toxicity rates per CTCAEv5.0. Secondary endpoints were 12-month local control (LC), progression free survival (PFS)-determined by treating physician and/or multidisciplinary tumor board-and overall survival (OS).RESULTS: Median follow-up was 13 months. Half had non-small cell lung cancer, 95.8% had ultracentral tumors, 57.7% had single prior thoracic RT course; 38.5%, 11.5% and 11.5% received concurrent chemotherapy, immunotherapy, and targeted agents, respectively. Minimum and median intervals between RT courses were 10 and 39.5 months, respectively; 94.7% of re-irradiation plans had overlapping 80% isodose volumes. Median OS and PFS were 13 and 10 months, respectively. Crude 12-month LC was 73.1%. Of those with a recurrence, the first recurrence occurred locally in 6 (54.6%), regionally in 3 (27.3%), and distantly in 8 (72.7%) patients. =G2 and =G3 toxicity rates were 30.8% and 7.69%, respectively (one G3 atrial fibrillation; one G5 pneumonitis). Using the American Radium Society guidelines for thoracic reirradiation, only 10.5% met all dose volume constraint recommendations.CONCLUSION: Definitive hyperfractionated thoracic re-RT was well tolerated with promising local control. =G3 toxicities were rare. Patients should be counseled on the low but potential risk of life-threatening toxicity. Consensus guidelines for dose constraints may be difficult to meet in reirradiation setting; in this cohort, rates of severe toxicity were low despite exceeding putative constraints in most patients.

View details for DOI 10.1016/j.ijrobp.2023.06.666

View details for PubMedID 37786208