Hi, my name is Christine, and I'll be presenting my research on pain outcomes in single fraction versus hyperfraction in a stereotactic body radiation therapy for spine metastasis. So a little bit of background, spine is the most common site for skeletal metastasis, and patients with spine meds are at risk for developing a variety of symptoms and complications including pain, disability, and spinal cord compression, and if left untreated, the risk of developing debilitating complications secondary to metastatic lesions increase. And radiation therapy is the treatment of choice in many of the spine meds cases, and out of the many radiotherapy options, SBRT is an emerging treatment option that offers efficient non-invasive treatment of spine neoplasms. The reading rationale for spine SBRT is its capacity to deliver a significantly higher biologically effective dose to the tumor while sparing surrounding normal structures. However, due to the ablative radiation doses involved, spine SBRT may lead to potential toxicities such as pain flares and vertebral compression fractures at a higher rate than conventional radiation therapy. Hence, it has been hypothesized or theorized that hypofractionated SBRT could reduce the side effects associated with high-dose single-fraction SBRT, but there is currently no conclusive data that exists to compare fractionated SBRT to single-fraction SBRT and on the advantage of hypofractionation over single-fraction on delivering higher radiation doses with reduced associated toxicities. And hence, this retrospective study aimed to provide evidence of the relationship between SBRT fractionation and long-term pain relief in patients with spine meds. And so we hypothesized that patients who received three-fraction SBRT will experience greater frequency of pain relief at three-month follow-up compared to those who received single-fraction SBRT. And so this was our inclusion criteria. We included patients who were above the age of 18 who had spine meds diagnosis and received SBRT between March 2018 to September 2019, and we excluded patients who did not receive either single-fraction or three-fraction SBRT, had received or were treated at multiple vertebral bodies simultaneously, and had incomplete follow-up data. And we ended up with a total of 156 patients for analysis. And in terms of our results, we had similar demographic characteristics for both single-fraction and three-fraction SBRT cohorts. In terms of tumor characteristics, we saw similar baseline tumor characteristics for both of these two groups as well. And in terms of baseline previous treatments, we found that a greater proportion of the patients in the three-fraction SBRT cohort had previous non-SBRT radiation therapy to spine, prior resection at the site of irradiation, and had treatments other than radiation therapy compared to those in the single-fraction SBRT. And in terms of baseline characteristics, we noticed that patients in the three-fraction SBRT cohort had worse baseline pain and functional status measured by the modified Rankin scale score and the Kramnovsky performance scale score compared to those in the single-fraction SBRT cohort. And when we looked at the pain outcomes at three-month follow-up, we found that the three-fraction SBRT group had increased frequency of pain improvement at three months post-SBRT compared to those in the single-fraction SBRT. And when we looked at the functional outcomes of these patients, we found that the three-fraction SBRT group didn't have a significant difference in the frequency of improvement in the MRS score three months post-SBRT compared to those who received single-fraction SBRT. But when we looked at the KPS score, we found that the three-fraction SBRT group had increased frequency of improved score compared to those in the single-fraction SBRT group. And so in conclusion, we found that patients who underwent three-fraction SBRT had higher frequency of improved pain outcomes at three-month follow-up compared to those who received single-fraction SBRT. And our results are important because the recently published NRG oncology-slash-RTOG-0631 trial showed that single-fraction SRS-slash-SBRT for treating spinal metastasis did not improve pain outcomes at three months compared to conventional single-fraction external beam radiation therapy. And the doses used were about 16 or 18 gray in the single-fraction SRS-slash-SBRT and about 8 gray in the single-fraction conventional EBRT. In comparison, our cohort had a median dose of 17 gray in the single-fraction SBRT and a total dose of 21 gray in the three-fraction SBRT for about 7 gray dose per fraction. And literature shows that a dose of 8 gray or greater produces effective tumor response and pain control. And so the results that we got with improved pain outcomes for the three-fraction SBRT could be because the individual dose of about 7 to 8 gray with a total dose equaling to about 21 gray takes advantage of both the low toxicity that's implied with the lower radiation dose and also with the higher radiation dose that is affected to the tumor that could result in improved pain control and as a result can be offered as an alternative to patients who do not qualify for the high-dose single-fraction SBRT treatment. Thank you!

pain outcomes

single-fraction SBRT

hypofractionated SBRT

spine metastasis

three-fraction SBRT