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Elie Massaad, Myron Rolle, Muhamed Hadzipasic, Ali Kiapour, Ganesh M. Shankar, and John H. Shin

OBJECTIVE

Achieving rigid spinal fixation can be challenging in patients with cancer-related instability, as factors such as osteopenia, radiation, and immunosuppression adversely affect bone quality. Augmenting pedicle screws with cement is a strategy to overcome construct failure. This study aimed to assess the safety and efficacy of cement augmentation with fenestrated pedicle screws in patients undergoing posterior, open thoracolumbar surgery for spinal metastases.

METHODS

A retrospective review was performed for patients who underwent surgery for cancer-related spine instability from 2016 to 2019 at the Massachusetts General Hospital. Patient demographics, surgical details, radiographic characteristics, patterns of cement extravasation, complications, and prospectively collected Patient-Reported Outcomes Measurement Information System Pain Interference and Pain Intensity scores were analyzed using descriptive statistics. Logistic regression was performed to determine factors associated with cement extravasation.

RESULTS

Sixty-nine patients underwent open posterior surgery with a total of 502 cement-augmented screws (mean 7.8 screws per construct). The median follow-up period for those who survived past 90 days was 25.3 months (IQR 10.8–34.6 months). Thirteen patients (18.8%) either died within 90 days or were lost to follow-up. Postoperative CT was performed to assess the instrumentation and patterns of cement extravasation. There was no screw loosening, pullout, or failure. The rate of cement extravasation was 28.9% (145/502), most commonly through the segmental veins (77/145, 53.1%). Screws breaching the lateral border of the pedicle but with fenestrations within the vertebral body were associated with a higher risk of leakage through the segmental veins compared with screws without any breach (OR 8.77, 95% CI 2.84–29.79; p < 0.001). Cement extravasation did not cause symptoms except in 1 patient who developed a symptomatic thoracic radiculopathy requiring decompression. There was 1 case of asymptomatic pulmonary cement embolism. Patients experienced significant pain improvement at the 3-month follow-up, with decreases in Pain Interference (mean change 15.8, 95% CI 14.5–17.1; p < 0.001) and Pain Intensity (mean change 28.5, 95% CI 26.7–30.4; p < 0.001).

CONCLUSIONS

Cement augmentation through fenestrated pedicle screws is a safe and effective option for spine stabilization in the cancer population. The risk of clinically significant adverse events from cement extravasation is very low.

Free access

Predicting tumor-specific survival in patients with spinal metastatic renal cell carcinoma: which scoring system is most accurate?

Presented at the 2020 AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves

Elie Massaad, Muhamed Hadzipasic, Christopher Alvarez-Breckenridge, Ali Kiapour, Nida Fatima, Joseph H. Schwab, Philip Saylor, Kevin Oh, Andrew J. Schoenfeld, Ganesh M. Shankar, and John H. Shin

OBJECTIVE

Although several prognostic scores for spinal metastatic disease have been developed in the past 2 decades, the applicability and validity of these models to specific cancer types are not yet clear. Most of the data used for model formation are from small population sets and have not been updated or externally validated to assess their performance. Developing predictive models is clinically relevant as prognostic assessment is crucial to optimal decision-making, particularly the decision for or against spine surgery. In this study, the authors investigated the performance of various spinal metastatic disease risk models in predicting prognosis for spine surgery to treat metastatic renal cell carcinoma (RCC).

METHODS

Data of patients who underwent surgery for RCC metastatic to the spine at 2 tertiary centers between 2010 and 2019 were retrospectively retrieved. The authors determined the prognostic value associated with the following scoring systems: the Tomita score, original and revised Tokuhashi scores, original and modified Bauer scores, Katagiri score, the Skeletal Oncology Research Group (SORG) classic algorithm and nomogram, and the New England Spinal Metastasis Score (NESMS). Regression analysis of patient variables in association with 1-year survival after surgery was assessed using Cox proportional hazard models. Calibration and time-dependent discrimination analysis were tested to quantify the accuracy of each scoring system at 3 months, 6 months, and 1 year.

RESULTS

A total of 86 metastatic RCC patients were included (median age 64 years [range 29–84 years]; 63 males [73.26%]). The 1-year survival rate was 72%. The 1-year survival group had a good performance status (Karnofsky Performance Scale [KPS] score 80%–100%) and an albumin level > 3.5 g/dL (p < 0.05). Multivariable-adjusted Cox regression analysis showed that poor performance status (KPS score < 70%), neurological deficit (Frankel grade A–D), and hypoalbuminemia (< 3.5 g/dL) were associated with a higher risk of death before 1 year (p < 0.05). The SORG nomogram, SORG classic, original Tokuhashi, and original Bauer demonstrated fair performance (0.7 < area under the curve < 0.8). The NESMS differentiates survival among the prognostic categories with the highest accuracy (area under the curve > 0.8).

CONCLUSIONS

The present study shows that the most cited and commonly used scoring systems have a fair performance predicting survival for patients undergoing spine surgery for metastatic RCC. The NESMS had the best performance at predicting 1-year survival after surgery.

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Elie Massaad, Philip J. Saylor, Muhamed Hadzipasic, Ali Kiapour, Kevin Oh, Joseph H. Schwab, Andrew J. Schoenfeld, Ganesh M. Shankar, and John H. Shin

OBJECTIVE

The effectiveness of starting systemic therapies after surgery for spinal metastases from renal cell carcinoma (RCC) has not been evaluated in randomized controlled trials. Agents that target tyrosine kinases, mammalian target of rapamycin signaling, and immune checkpoints are now commonly used. Variables like sarcopenia, nutritional status, and frailty may impact recovery from spine surgery and are considered when evaluating a patient’s candidacy for such treatments. A better understanding of the significance of these variables may help improve patient selection for available treatment options after surgery. The authors used comparative effectiveness methods to study the treatment effect of postoperative systemic therapies (PSTs) on survival.

METHODS

Univariable and multivariable Cox regression analyses were performed to determine factors associated with overall survival (OS) in a retrospective cohort of adult patients who underwent spine surgery for metastatic RCC between 2010 and 2019. Propensity score–matched (PSM) analysis and inverse probability weighting (IPW) were performed to determine the treatment effect of PST on OS. To address confounding and minimize bias in estimations, PSM and IPW were adjusted for covariates, including age, sex, frailty, sarcopenia, nutrition, visceral metastases, International Metastatic RCC Database Consortium (IMDC) risk score, and performance status.

RESULTS

In total, 88 patients (73.9% male; median age 62 years, range 29–84 years) were identified; 49 patients (55.7%) had an intermediate IMDC risk, and 29 (33.0%) had a poor IMDC risk. The median follow-up was 17 months (range 1–104 months) during which 57 patients (64.7%) died. Poor IMDC risk (HR 3.2 [95% CI 1.08–9.3]), baseline performance status (Eastern Cooperative Oncology Group score 3 or 4; HR 2.7 [95% CI 1.5–4.7]), and nutrition (prognostic nutritional index [PNI] first tertile, PNI < 40.74; HR 2.69 [95% CI 1.42–5.1]) were associated with worse OS. Sarcopenia and frailty were not significantly associated with poor survival. PST was associated with prolonged OS, demonstrated by similar effects from multivariable Cox analysis (HR 0.55 [95% CI 0.30–1.00]), PSM (HR 0.53 [95% CI 0.29–0.93]), IPW (HR 0.47 [95% CI 0.24–0.94]), and comparable confidence intervals. The median survival for those receiving PST was 28 (95% CI 19–43) months versus 12 (95% CI 4–37) months for those who only had surgery (log-rank p = 0.027).

CONCLUSIONS

This comparative analysis demonstrated that PST is associated with improved survival in specific cohorts with metastatic spinal RCC after adjusting for frailty, sarcopenia, and malnutrition. The marked differences in survival should be taken into consideration when planning for surgery.

Free access

Elie Massaad, Natalie Williams, Muhamed Hadzipasic, Shalin S. Patel, Mitchell S. Fourman, Ali Kiapour, Andrew J. Schoenfeld, Ganesh M. Shankar, and John H. Shin

OBJECTIVE

Frailty is recognized as an important consideration in patients with cancer who are undergoing therapies, including spine surgery. The definition of frailty in the context of spinal metastases is unclear, and few have studied such markers and their association with postoperative outcomes and survival. Using national databases, the metastatic spinal tumor frailty index (MSTFI) was developed as a tool to predict outcomes in this specific patient population and has not been tested with external data. The purpose of this study was to test the performance of the MSTFI with institutional data and determine whether machine learning methods could better identify measures of frailty as predictors of outcomes.

METHODS

Electronic health record data from 479 adult patients admitted to the Massachusetts General Hospital for metastatic spinal tumor surgery from 2010 to 2019 formed a validation cohort for the MSTFI to predict major complications, in-hospital mortality, and length of stay (LOS). The 9 parameters of the MSTFI were modeled in 3 machine learning algorithms (lasso regularization logistic regression, random forest, and gradient-boosted decision tree) to assess clinical outcome prediction and determine variable importance. Prediction performance of the models was measured by computing areas under the receiver operating characteristic curve (AUROCs), calibration, and confusion matrix metrics (positive predictive value, sensitivity, and specificity) and was subjected to internal bootstrap validation.

RESULTS

Of 479 patients (median age 64 years [IQR 55–71 years]; 58.7% male), 28.4% had complications after spine surgery. The in-hospital mortality rate was 1.9%, and the mean LOS was 7.8 days. The MSTFI demonstrated poor discrimination for predicting complications (AUROC 0.56, 95% CI 0.50–0.62) and in-hospital mortality (AUROC 0.69, 95% CI 0.54–0.85) in the validation cohort. For postoperative complications, machine learning approaches showed a greater advantage over the logistic regression model used to develop the MSTFI (AUROC 0.62, 95% CI 0.56–0.68 for random forest vs AUROC 0.56, 95% CI 0.50–0.62 for logistic regression). The random forest model had the highest positive predictive value (0.53, 95% CI 0.43–0.64) and the highest negative predictive value (0.77, 95% CI 0.72–0.81), with chronic lung disease, coagulopathy, anemia, and malnutrition identified as the most important predictors of postoperative complications.

CONCLUSIONS

This study highlights the challenges of defining and quantifying frailty in the metastatic spine tumor population. Further study is required to improve the determination of surgical frailty in this specific cohort.