Pulsed Reduced Dose-rate Radiotherapy as Re-irradiation for Brain Metastasis in a Patient with Lung Squamous-celled Carcinoma

摘要

The recurrence and progression of brain metastases after brain irradiation are a major cause of mortality and morbidity in patients with cancer. The risk of radiation-induced neurotoxicity and efficacy probably leads oncologists to not consider re-irradiation. We report the case of a 48-year-old Asian male diagnosed with squamous cell lung cancer and multiple brain metastases initially treated with 40 Gy whole-brain radiotherapy and 20 Gy partial brain boost. Fourteen gray stereotactic radiosurgery as salvage for brain metastases in the left occipital lobe was performed after initial irradiation. The recurrence of brain metastases in the left occipital lobe was demonstrated on magnetic resonance imaging at 9 months after initial radiotherapy. He received the second course of 28 Gy stereotactic radiosurgery for the recurrent brain metastases in the left occipital lobe. The third relapse of brain metastases was demonstrated by a magnetic resonance imaging scan at 7 months after the second radiotherapy. The third course of irradiation was performed because he refused to undergo surgical resection of the recurrent brain metastases. The third course of irradiation used a pulsed reduced dose-rate radiotherapy technique. It was delivered in a series of 0.2 Gy pulses separated by 3-min intervals. The recurrent brain metastases were treated with a dose of 60 Gy using 30 daily fractions of 2 Gy. Despite the brain metastases receiving 162 Gy irradiation, this patient had no apparent acute or late neurologic toxicities and showed clinical improvement. This is the first report of the pulsed reduced dose-rate radiotherapy technique being used as the third course of radiotherapy for recurrent brain metastases.