## 4 Discussion  
In this series, while investigating the effectiveness of SBRT with respect to pain control of spinal metastases, we found a reduction in the VAS score (last control data between one and three months after radiotherapy) of more than 1.5 points (2.48 VAS pre-treatment vs. 0.97 VAS post-treatment, \(p<0.01\)). It is relevant to note that 17 lesions were asymptomatic before treatment. We also found two factors that were variably significant: the time elapsed from bone metastasis to the start of SBRT and the prescribed dose. In this regard, the longer the interval between bone metastasis and SBRT initiation, the worse it is for pain relief (\(p<0.01\)), and a higher prescribed dose is better for pain relief (\(p<0.01\)). Three covariates were significant within this multivariate model: female sex (\(p<0.05\)); histology, observation of higher pain scores in patients with other malignancies compared to adenocarcinomas (\(p<0.05\)); and the lack of previous surgery (\(p<0.01\)). Thus, female sex, adenocarcinoma tumors, and the lack of previous surgery were associated with a better response to SBRT in our study. Of note, female gender is related to adenocarcinoma tumor type in our study (\(p<0.0007\)), and it is not related to previous surgery. Patients with metastases in lower spinal regions also showed lower VAS scores compared to those with cervical lesions. Individuals with lower VAS scores before treatment showed higher scores after treatment. Finally, patients with a higher CI showed higher pain scores (exacerbation effect due to peripheral tissue inflammation). In addition, SBRT can be administered with very low toxicity (only one patient experienced grade III radiodermatitis). In the study conducted by [PERSON] and colleagues, the median age was similar (62 years; range 27-88) to that of our own series (56 years; range 28-80). The gender distribution also exhibited similarities: 15 female and 11 male patients in both studies. However, there were differences in the number of spinal metastatic lesions treated. [PERSON] et al. addressed 32 lesions, while our series involved 43 lesions. Notably, the most frequently treated lesions in their study were pulmonary metastases (n = 19), whereas our series predominantly focused on breast metastases. Regarding treatment locations, both studies emphasized the thoracic spine as the most common site (n = 18 in [PERSON] et al. vs. n = 21 in our study). The lumbosacral spine followed closely (n = 12 in [PERSON] et al. vs. n = 14 in our study), and the cervical spine was less frequently treated (n = 2 in [PERSON] et al. vs. n = 8 in our study) [2]. In terms of dose fractionation, [PERSON] et al. primarily used 24 Gy in 3 fractions, whereas our study employed 27 Gy in 3 fractions. Acute toxicity, mainly characterized by pain flare, occurred in 16% of the treated lesions and could be managed with analgesics and steroids. Interestingly, in our series, the flare effect was observed in patients with a higher CI. Importantly, no radiation-induced myelopathy was reported by [PERSON] et al., and only one case of grade III dermatitis occurred in our study. Based on these findings, we can confidently conclude that SBRT is a safe treatment [2]. Several studies have reviewed SBRT's pain control and other clinical benefits in the literature. In their study, [PERSON] et al. compared SBRT and cEBRT in patients with spinal metastatic lesions with palliative intent. The median follow-up was almost one year. Median survival was 21.6 months for SBRT and 18.9 months for cEBRT (\(p=0.428\)). The risk of local failure of SBRT vs. cEBRT was 2.8% vs. 11.2% at 6 months, 6.1% vs. 28.4% at 12 months, and 14.8% vs. 35.6% at 24 months. Time to re-irradiation was favorable in the SBRT group (2.2% vs. 15.8% (\(p=0.002\)) and 22.9 months vs. 9.5 months, respectively). However, the rate of vertebral fractures was higher in SBRT (8 of 12 vs. 4 of 12).