Outcomes of 30 Gy/5 Fr Hypofractionated Stereotactic Radiation Therapy for Small Brain Metastases (≤2 cm).

BACKGROUND/AIM: Stereotactic radiosurgery (SRS)-used for brain metastases (BMs) with a tumor diameter of ≤2 cm-has a high local control rate, however, it can cause symptomatic radiation-induced brain necrosis. Hypofractionated stereotactic radiation therapy (HFSRT) is not commonly used for such lesions and its effectiveness remains unknown. Herein, the efficacy of 30 Gy 5-fraction HFSRT for treating BMs of <2 cm was retrospectively evaluated. PATIENTS AND METHODS: Patients who received HFSRT and had a gross tumor volume (GTV) of ≤2 cm in maximum diameter were included in the study (49 patients; 179 BMs; median follow-up period, 11.9 months). RESULTS: The mean GTV Peripheral Dose (D95) was 36.2 Gy. The local control (LC) rates at 1 and 2 years were 93.0% and 81.5%, respectively, for all lesions. The 1-year LC rates were 93.6% and 92.0% for ≤1.0-cm and 1.0-2.0-cm lesions, respectively. Multivariate analysis revealed that the only significant difference was in GTV maximal tumor diameter (HR=1.961, p=0.0002). Notably, only one patient had asymptomatic radiation necrosis. CONCLUSION: Owing to the high toxicity of SRS, 5-fraction HFSRT can be an effective treatment strategy for BMs of <2 cm.

Radiation-induced sarcoma after radiation therapy for prostate adenocarcinoma.

INTRODUCTION: Radiation therapy is widely used for prostate cancer, but radiation-induced sarcomas have been rarely reported. CASE PRESENTATION: A 77-year-old Japanese male was diagnosed with prostate cancer and received a combined androgen blockade and radiation therapy (total dose of 76 Gy). Five years after the radiation therapy, testicular pain and dysuria appeared. Computed tomography showed a soft tissue dense mass with invasion to the right subpubic ramus and prostate, mainly to the perineum. A needle biopsy revealed the pathological features of high-grade sarcoma. The patient was diagnosed with radiation-induced sarcoma based on the cancer's occurrence in the vicinity of the radiation field. CONCLUSION: Although irradiation is one of the important treatments for prostate cancer, the risk of radiation-induced malignancy should be considered.