Abstract
Introduction
Treatment of spinal metastatic disease has evolved with the advent of advanced interventional, surgical and radiation techniques. Spinal Oligometastatic disease is a low volume disease state where en bloc resection of the tumour, based on oncological principles, can achieve maximum local control (MLC). Hybrid therapy incorporating Separation surgery (>2mm clearance of the thecal sac) and Stereotactic Ablative Radiotherapy (SABR) offer an alternative approach to achieving MLC. Hybrid therapy is also a viable option in patients eligible for SBRT who have failed conventional radiation therapy. En-bloc surgery may be a suitable option for those patients who are ineligible for or have failed SBRT. A multidisciplinary approach is particularly important in the decision-making process for these patients. Metal free instrumentation is aiding the optimization of these surgeries. The authors present a supra-regional centre's experience in managing spinal oligometastases.
Methods
Retrospective review of oligometastatic spinal disease at a supra-regional centre between 2017 and 2021. Demographics, operative course, complications and Instrument type are examined.
Results
Demographics: 24 patients with mean age 53.8y (range 12–77), 44% (40y–59y), 40% (60y–69y); 51% Male.
Histology: Breast, Renal and Sarcoma accounted for 16.7% each; Thyroid, Prostate and Chordoma accounted for 8.3% each. Primary disease 7%, Synchronous 15%, Metachronous 78%.
Instrumentation: Carbon-fibre (85%), TiAl (11%), Non-Instrumented (3%).
Separation Surgery (70%), En-bloc resection/Tomita surgery (30%); SABR/Proton Beam Planned: 70%.
Average length of hospital stays 19.1 days; twenty patients required intensive care admission for an average 2.7 days.
30 Day Mortality 8.3% (n=2: COVID-19 during admission and ventriculitis post discharge), 1y Mortality – 16.7%, 3y Mortality – 25%; Synchronous Mortality 75% (n=3) at 3 years.
30 Day infection rate 3%; 1y infection rate 7%.
1 Non-instrumented case developed proximal junctional failure post proton beam therapy and required a vascularised fibular strut graft.
2-year Revision for Local Recurrence 5% (Revision at 23 months).
Conclusion
There are very few case series of oligometastatic spinal disease due to the relatively new concept of adjuvant SABR and its limited availability. Solid tumours pre-dominated the histology in our series with metachronous disease being the most commonly operated disease state. 92% of cases were eligible for SABR. The majority (85%) of cases were performed with Carbon-fibre instrumentation and has been shown to be safe with no mechanical failures in this series. Infection rates are in keeping with patients requiring radical radiotherapy with 3% early and 7% late. 30-day mortality was 8.3%, 1y=16.7% and 25% at last follow up. Mortality, as expected, is highest within the synchronous disease group and should be operated on sparingly. With the current management strategy, there was no local recurrence at 1 year and excellent local recurrence rate at 2 years (5%).
Although radical en bloc surgery carries significant morbidity, it should be considered in selective cases to achieve MLC. All Oligometastatic cases deserve extra consideration and specialist MDT as not all are suitable for SABR. Multimodal Hybrid therapy, incorporating less invasive surgical techniques and SABR, represents a paradigm shift in achieving MLC in oligometastatic spinal disease.
