Incidence of local and marginal treatment failure following postoperative single fraction spine stereotactic radiosurgery
Boyce-Fappiano D, Elibe E, Siddiqui MSU, Lee I, Rock J, and Siddiqui F. Incidence of local and marginal treatment failure following postoperative single fraction spine stereotactic radiosurgery. Int J Radiat Oncol Biol Phys 2017; 99(2 Suppl):E517.
Int J Radiat Oncol Biol Phys
Purpose/Objective(s): Although stereotactic radiosurgery (SRS) is becoming a prominent primary treatment option for metastatic and primary tumors of the spine, surgical resection remains the treatment of choice in many instances such as spinal cord compression. Often in cases of surgical resection, post-operative SRS is utilized as an adjuvant therapy to ensure local and marginal tumor control. Unfortunately, the radiological changes that occur in the spine after surgical resection can sometimes prove to be challenging for treatment planning as bleeding and inflammation can blur the boundaries between tumor and healthy tissue. Our institution aimed to determine our local and marginal failure rates of post-operative single fraction SRS. Purpose/Objective(s): A total of 46 patients (65 vertebral bodies) underwent surgical resection followed by post-operative single fraction SRS for spinal tumors between 06/2001 and 12/2015. An IRB approved retrospective analysis of electronic medical records for clinical exams, and computed tomography & magnetic resonance imaging was performed. Post treatment radiographic tumor control monitoring for local and marginal failure were the primary endpoints of this study. Results: The patient population consisted of 58% males, 41% females with a median age of 63 years. 54%, 37%, and 9% of patients are Caucasian, African American, and of other ethnicities respectively. 30 (65%) of patients are deceased with a median survival time of 3.8 months (range 21 days-8.6 years). The three most common primary tumor histologies were lung (21%), breast (13%), and multiple myeloma (11%). The location of post-operative SRS was: 6.5% cervical, 78.3% thoracic, 13% lumbar, and 2.2% sacrum. Median dose of SRS was 17 Gy (range 10-18 Gy). Median target volume was 51.2 cc (range 2.76-211 cc). Follow-up for treatment response was available in 30 (65%) of patients with a median follow-up time of 6.1 months (range 48 days-2.3 years). In-field failure occurred in 5 patients (16.7%), and marginal failure occurred in 3 patients (10%), the remaining 22 patients (73%) had excellent local control with no signs of recurrence. No specific tumor histology was correlated with treatment failure. Conclusion: Our observations suggest that in-field and marginal treatment failure following post-operative SRS occurs in a significant number of cases. However, in a majority of cases post-operative SRS is well-tolerated with good local control rates. Therefore, further work must be considered to improve post-operative treatment planning and physicians must take greater precautions when encountering such cases.