Background: This study aimed to evaluate the differences in common types of epidermal growthfactor receptor (EGFR) mutations in non-small cell lung cancer (NSCLC) with brain metastasis (BM) treated using linear accelerator-based stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (fSRT). Methods: Between January 2011–December 2023, among 294 consecutive patients with BMfrom NSCLC, 84 patients with EGFR-mutated NSCLC were enrolled in this study. Results: The median follow-up time after SRS/fSRT was 20.1 months (range: 0.6–109.7months), while the median overall survival (mOS) after SRS/fSRT was 25.1 months (95% confidence interval [CI]: 18.4–33.5 months). The mOS after initial treatment for NSCLC was 56.2 months (95% CI:41.7–77.0 months). The mOS after SRS/fSRT in 34 patients with exon 19 deletions and 45 patients with exon 21 mutations with L858R was 20.4 months (95% CI: 13.6–55.9 months) and 28.5 months (95% CI: 16.2–33.5). The two groups showed no difference in the mOS. In univariate analyses using the Cox proportional hazards model, no prognostic factors associated with prolonged survival were identified except for good pretreatment Karnofsky Performance Status score and no prior tyrosine kinase inhibitor use before SRS/fSRT in EGFR-mutated NSCLC. There was no difference in both distant failure and local control in the two groups. Conclusion The difference in survival between EGFR subtypes (exon 21 L858R mutations vs.exon 19 deletion) was not observed after SRS/fSRT in NSCLC.

Purpose: This study evaluated the clinical utility of the highest bone scan index (BSI), among other BSIs, for each bone metastatic site in patients with bone metastatic castration–resistant prostate cancer (bmCRPC). Methods: Thirty patients, diagnosed with bmCRPC by bone scintigraphy, were included. Total BSI, the number of hot spots, and regional BSI on each hot spot from bone scintigraphy at diagnosis with bmCRPC were evaluated by VSBONE BSI®. Highest regional BSI was defined as the highest value among regional BSIs on each hot spot in each patient. Related factors to overall survival and skeletal-related events (SREs) were evaluated using the Cox proportional-hazards model. Results: The median follow-up time from diagnosis with bmCRPC was 29.0 months. During this time, 24 patients died, of which 22 patients died from prostate cancer. On univariate analysis, alkaline phosphatase (ALP) [Hazard ratio (HR): 5.96, 95% confidence interval (CI): 2.05–17.3] and highest regional BSI (HR: 2.01, 95% CI: 1.17–7.05) had significant correlation with overall survival. On multivariate analysis, ALP (HR: 4.79, 95% CI: 1.61–14.2) had significant correlation with overall survival. SREs were found in eight patients. Only the highest regional BSI (HR: 9.99, 95% CI: 2.46–40.6) significantly correlated with SREs on univariate analysis. Conclusion Highest regional BSI may provide important information regarding prognosis and SREs in patients with bmCRPC.