The Incidence and Risk Factors of Symptomatic Local Recurrence Following Surgical Treatment for Spinal Metastasis with Involvement of All Three Columns: Focusing on the Extent of Tumor Removal.

Backgroud: Although symptomatic local recurrence (SLR) of spinal metastasis is relatively common after aggressive surgery, there have been few studies on SLR according to the extent of tumor removal. This study aimed to evaluate the incidence of SLR after surgery in spinal metastasis and analyze the risk factors of SLR.

Methods: This study included patients with spinal metastasis to all 3 vertebral columns. SLR was defined as the occurrence of new symptoms, confirmed by radiologic regrowth of tumor. The extent of tumor removal was classified into 3 types (corpectomy, separation surgery, and only posterior column removal). The Kaplan-Meier method was used to analyze the SLR rate after surgery. The presumed risk factors of SLR were evaluated using log-rank test and Cox regression analysis.

Results: This study included 102 patients with a mean follow-up period of 17.7 months (range, 3-84 months). After surgical treatment, SLR was confirmed in 35 patients (34.3%). Kaplan-Meier analysis predicted that the incidence of SLR was 4.4% at 6 months, 21.5% at 12 months, 34.0% at 18 months, and 42.7% at 24 months. In the univariate analysis, the primary malignancy site, number of vertebral metastases, and surgery for progressed tumor after previous radiation therapy were significant (p = 0.042, p = 0.048, and p = 0.008, respectively). No significant differences were observed in the extent of tumor removal (p = 0.536). In the multivariate analysis, the significant risk factors of SLR included only previous radiation therapy (p = 0.012). The risk of SLR was 2.8 times higher in patients who received surgery for progressed tumor after previous radiation therapy than in those without it.

Conclusions: The SLR of spinal metastasis was predicted in 21.5% of patients at 1 year after surgical treatment. The extent of tumor removal did not seem to affect SLR. Surgery for progressed tumor after previous radiation therapy was confirmed as the only substantial risk factor. Therefore, the tumor's response to preoperative radiation therapy is the most important factor in determining SLR.