Separation Surgery Followed by Conformal Postoperative Spine Stereotactic Body Radiation Therapy Does Not Increase Risk of Adjacent Spine Level Progression in the Management of Spine Metastases.

Abstract

Objectives: To determine if piecemeal separation surgery, in conjunction with smaller treatment volumes utilized with spine stereotactic radiation therapy (S-SBRT), increased the risk of adjacent level progression (ALP).

Methods: We performed a retrospective analysis of a prospectively maintained database of adult spine oncologic patients who underwent SBRT to the spine at University of Michigan from 2010 to 2021. We compared ALP in patients undergoing SBRT who had pretreatment surgery with those who did not.

Results: Four hundred and ninety-eight treatment sites were identified in 417 patients. Of these, 366 (73.5%) were treated with SBRT alone and 132 (26.5%) were treated with surgery followed by S-SBRT. Patients treated with SBRT alone were significantly older (63.3 y) compared with the surgery plus SBRT group (60.2 y; P=0.02). More radiosensitive histologies were treated with SBRT alone (34%) compared with 11% for the surgery plus SBRT group (P<0.001). Lesions treated in the surgery plus SBRT group had significantly more severe metastatic epidural spinal cord compression (65%) compared with the SBRT only group (8%) (P<0.001). Both infield progression (9.3% vs. 7.6%; P=0.43) and ALP (21.3% vs. 18.9%; P=0.37) were not significantly different between groups.

Conclusions: Spine oncology patients treated with surgery followed by conformal postoperative S-SBRT had similar infield and ALP compared with patients receiving SBRT alone, suggesting that piecemeal separation surgery does not locally spread tumor cells, leading to an increased risk of ALP failure, and supporting the use of conformal postoperative S-SBRT.