Update on the Management of Sacral Metastases

Stereotactic body radiation therapy for spinal metastases: a novel local control stratification by spinal region

OBJECTIVE

This study evaluated a large cohort of patients treated with stereotactic body radiation therapy for spinal metastases and investigated predictive factors for local control, local progression-free survival (LPFS), overall survival, and pain response between the different spinal regions.

METHODS

The study was undertaken via retrospective review at a single institution. Patients with a tumor metastatic to the spine were included, while patients with benign tumors or primary spinal cord cancers were excluded. Statistical analysis involved univariate analysis, Cox proportional hazards analysis, the Kaplan-Meier method, and machine learning techniques (decision-tree analysis).

RESULTS

A total of 165 patients with 190 distinct lesions met all inclusion criteria for the study. Lesions were distributed throughout the cervical (19%), thoracic (43%), lumbar (19%), and sacral (18%) spines. The most common treatment regimen was 24 Gy in 3 fractions (44%). Via the Kaplan-Meier method, the 24-month local control was 80%. Sacral spine lesions demonstrated decreased local control (p = 0.01) and LPFS (p < 0.005) compared with those of the thoracolumbar spine. The cervical spine cases had improved local control (p < 0.005) and LPFS (p < 0.005) compared with the sacral spine and trended toward improvement relative to the thoracolumbar spine. The 36-month local control rates for cervical, thoracolumbar, and sacral tumors were 86%, 73%, and 44%, respectively. Comparably, the 36-month LPFS rates for cervical, thoracolumbar, and sacral tumors were 85%, 67%, and 35%, respectively. A planning target volume (PTV) > 50 cm3 was also predictive of local failure (p = 0.04). Fewer cervical spine cases had disease with PTV > 50 cm3 than the thoracolumbar (p = 5.87 × 10-8) and sacral (p = 3.9 × 10-3) cases. Using decision-tree analysis, the highest-fidelity models for predicting pain-free status and local failure demonstrated the first splits as being cervical and sacral location, respectively.

CONCLUSIONS

This study presents a novel risk stratification for local failure and LPFS by spinal region. Patients with metastases to the sacral spine may have decreased local control due to increased PTV, especially with a PTV of > 50 cm3. Multidisciplinary care should be emphasized in these patients, and both surgical intervention and radiotherapy should be strongly considered.

Reducing Surgical Site Infections in Spine Tumor Surgery: A Comparison of Three Methods

STUDY DESIGN

Case control series.

OBJECTIVE

The aim of this study was to evaluate and compare the effectiveness of methods to decrease surgical site infections (SSIs) following spine tumor surgery.

SUMMARY OF BACKGROUND DATA

With the aging population of the United States, the prevalence of cancer and associated metastatic spine disease is increasing. The most common complication of spine tumor surgery is SSI.

METHODS

This a single-institution case-control series of patients undergoing spine tumor surgery from June 2003 to October 2018. Patients were grouped into the following groups: Betadine irrigation and intrawound vancomycin powder (BIVP), intrawound vancomycin powder only (IVP), and patients receiving neither (NONE). The primary outcome was SSIs/wound complications.

RESULTS

One hundred fifty-one spine tumor patients undergoing 174 procedures meeting our inclusion criteria were identified. The BIVP group had 60 patients (73 procedures); the IVP group had 46 patients (47 procedures); and the NONE group had 45 patients (54 procedures). The overall infection rate was 8.6% of all procedures (15/174) and 9.9% (15/151) of all patients. Bivariate analysis comparing patients with and without infections noted the patients with SSIs had significantly higher rates of preoperative radiation treatment (53.3% in infection group vs. 25.5% in noninfection group), P = 0.02. Patients undergoing procedures in the BIVP group had a significantly lower rate of infections (2.7%) than the patients in the IVP (12.8%) and NONE (13%) groups, P = 0.04. Stepwise regression analysis was used to evaluate further factors associated with SSIs. Elevated BMI was significantly associated with SSIs in the model [P = 0.02, odds ratio (OR) 1.14]. BIVP was also protective against infections as compared to the IVP and NONE groups, P = 0.02, OR 0.02.

CONCLUSION

BIVP led to a significant decrease in SSI rates following spine tumor surgery. Administration of BIVP is not time consuming and decreased SSI rates.

LEVEL OF EVIDENCE

3.