Total en bloc spondylectomy for spinal metastasis of differentiated thyroid cancers: A long-term follow-up

Study Design: A retrospective case series. Objective: To evaluate the long-term effectiveness and problems of total en bloc spondylectomy (TES) for treating metastatic thyroid cancer of the spine. Summary of Background Data: Although TES is indicated for low-grade malignant spinal tumors, its efficacy in treating thyroid cancer metastases in the spine is uncertain. Methods: This study followed 8 patients who underwent TES for spinal metastasis of thyroid cancer (5 males, 3 females; mean age, 55.3 y; mean follow-up period, 6.4 y), 6 with follicular carcinomas and 2 with papillary carcinomas. In 6 patients without a marked paravertebral tumor extension, TES was performed using a posterior approach. Two patients had prominent anterior or anterolateral tumor extension into the thoracic and retroperitoneal cavities, and a combined anterior and posterior approach was used. We evaluated the patients' clinical symptoms, operative procedures, complications, and prognoses. Results: Before surgery, the patients' neurological status was evaluated by the Frankel classification (grade C, 4 patients; grade D, 1 patient; grade E, 3 patients) and Tokuhashi scores (9, 1 patient; 11, 2 patients; 13 and 14, 1 patient each; 15, 3 patients). One year after surgery, all the patients had improved by at least a Frankel grade, and 4 patients classified as grade C before surgery had become ambulatory. At the final follow-up (average of 6.4 y), 5 patients had a grade E Frankel classification and 1 had grade D, but 2 patients had suffered neurological deterioration, because of tumor recurrence, at the same level as the TES in one patient and at an adjacent level in the other. At follow-up, all patients were alive; 5 showed no evidence of disease. Two patients experienced rod breakage, at 2.8 and at 3.3 years after TES, and 1 patient suffered an endplate fracture 6 months after TES; this patient developed a late infection, 7 years after TES. Conclusions: TES was effective in controlling spinal thyroid cancer metastasis locally and in preserving the ability to walk. However, instrumentation failure and other late complications arose during the patients' long survival times after TES.