Earlier Radiation Is Associated with Improved 1-Year Survival After Metastatic Spine Tumor Surgery.

OBJECTIVES: In patients undergoing metastatic spine surgery, we sought to: 1) report time to postoperative radiation therapy (RT), 2) describe the predictive factors of time to postoperative RT, and 3) determine if earlier postoperative RT is associated with improved local recurrence (LR) and overall survival (OS).

METHODS: A single-center, retrospective cohort study was undertaken of all patients undergoing spine surgery for extradural metastatic disease and receiving RT within 3-months postoperatively between 02/2010-01/2021. Time to postoperative RT was dichotomized at <1month vs. 1-3months. The primary outcomes were LR, OS, and 1-year survival. Secondary outcomes were wound complication, Karnofsky Performance Scale (KPS), and Modified McCormick Scale (MMS). Regression analyses controlled for age, BMI, tumor size, preoperative RT, preoperative/postoperative chemotherapy, and type of RT.

RESULTS: Of 76 patients undergoing spinal metastasis surgery and receiving postoperative RT within 3-months, 34(44.7%) received RT within 1month and 42(55.2%) within 1-3months. Patients with larger tumor size (β=-3.58,95%CI=-6.59,-0.57,p=0.021) or new neurological deficits (β=-16.21,95%CI=-32.21,-0.210,p=0.047) had a shorter time to RT. No significant association was found between time to RT and LR or OS on multivariable logistic/Cox regression. However, patients who received RT between 1-3month had a lower odd of 1-year survival compared to those receiving RT within 1month (OR=0.18,95%CI=0.04-0.74,p=0.022). Receiving RT within 1month vs. 1-3month was not associated with wound complications (7.1% vs. 2.9%,p=0.556)(OR=4.40,95%CI=0.40-118.0,p=0.266) or KPS/MMS.

CONCLUSIONS: Spine surgeons, oncologists, and radiation oncologists should make every effort to start RT within 1 month to improve 1-year survival after metastatic spine tumor surgery.