Thesis Presentation-Abbreviated version

Modeling Survival After Surgery On The Metastatic SpineAhmer Ghori MD, Dana Leonard BA, Andrew Schoenfeld MD, Ehsan Saadat MD, Mitch B Harris MD

Ahmer K Ghori MDHarvard University Orthopaedic Surgery Program

My Goal Today

Review the past and present state of managing metastatic spine.

Discuss how our model may improve the present state.

Historical: No advantage with surgery

Present: Surgery helps

Limitation: Can’t predict post op survival

Who to operate on?

Our Model

Future: Patient specific management

Evolution of spinal

instrumentation

Patient Specific

Variables

Predict survival reliably

Historic Management: Why no surgery ?

Laminectomy was the only surgical option.

No difference in laminectomy + radiation versus radiation alone with regard to: pain relief ambulation sphincter function.

Young et al 1980

Paradigm Shift

Evolution of modern spinal instrumentation.Wider decompressions

&Robust stabilization

Modern Literature

Surgery helps in managing metastatic spine

Pain.

Ambulation.

Maintain independence at end of life.Direct decompressive surgical resection in the treatment of spinal cord compression caused by metastatic cancer: a randomised trial. The Lancet. 2005;366(9486):643–648. doi:10.1016/S0140-6736(05)66954-1.

Present Limitations Choosing surgical candidates

Not a reliable process.

Existing models: Do not predict survival reliably ! Correlation with survival 20-50 %

Ragel, B. T. et al. Life Expectancy and Metastatic Spine Scoring Systems: An Academic Institutional Experience. J Spinal Disord Tech (2014). Wang M, Bünger CE, Li H, Wu C, Høy K, Niedermann B, et al. Predictive value of Tokuhashi scoring systems in spinal metastases, focusing on various primary tumor groups: Evaluation of 448 patients in the Aarhus spinal metastases database. Spine 2012;37: 573-582.

Harrington Score

Tokuhashi Score

Tomita Score

Tomita et al. Surgical strategy for spinal metastases. Spine (2001) vol. 26 (3) pp. 298-306

Modified Bauer Score

Existing scoring systems do not capture patient’s overall health state.

Ghori et al 2015

Why can’t we predict survival ?

Let’s consider a hypothetical scenario

Bauer Score: 4 Can we predict post op survival from a score of 4 alone?

Consider 2 patients

Female • Breast cancer• No visceral metastases• Solitary spine metastasis

Modified Bauer Score 4 Case 1

First patient is :

• Young• Can Ambulate• Normal

nutrition status.

Modified Bauer Score 4 Case 1

Modified Bauer Score 4: Case 2 Second patient is:

• Old.• Cannot ambulate.• Poor nutritional status.

Modified Bauer Score 4 Case 2

Both patients have a Bauer score of 4 !

Differences will affect survival

Need a model that is more specific.

Existing Models: Shortcoming

VS.

Hypothesis

Model

Quantifies patient health status

Predict post op survival reliably

Ghori et al 2015

Methods Retrospective review at four participating

institutions (BIDMC, BWH, MGH, Dartmouth).

Identify patients who had undergone spine surgery for metastatic disease between 2007 and 2013. Over 300 patients across 5 years included.

Ghori et al 2015

Variables we studied Main predictors of survival we studied

Pre-operative modified Bauer score Pre- operative ambulatory status Pre-operative serum albumin level. Pre-operative serum creatinine level. Primary tumor type. Demographics: age, sex, race. Number of comorbidities. We coined these “healthiness states”

Ghori et al 2015

Ghori et al 2015: Our Model Analyzed all permutations of these three variables. Chose combination which has best correlation with survival.

High Bauer score (3,4): 2 points

Intact ambulatory status: 1 point

Normal serum albumin level : 1 point

Ceiling score of 3.

Ghori et al 2015

Ghori et al 2015: Model

3

2

1

0

3 vs. 2 vs. 1 vs. 0P < 0.001

Ghori et al 2015 Our Model was able to explain 74% of the variation

in 1-year survival. What does that mean?

In contrast existing scoring systems : 20- 50 % correlation with survival

Ragel, B. T. et al. Life Expectancy and Metastatic Spine Scoring Systems: An Academic Institutional Experience. J Spinal Disord Tech (2014). Wang M, Bünger CE, Li H, Wu C, Høy K, Niedermann B, et al. Predictive value of Tokuhashi scoring systems in spinal metastases, focusing on various primary tumor groups: Evaluation of 448 patients in the Aarhus spinal metastases database. Spine 2012;37: 573-582.

Our Model

Practical advantage ?

Let us apply it to our two cases.

High modified Bauer score and

1. Intact ambulation2. Normal albumin

78% survival

Modified Bauer Score

(4): 59% survival

Case 1:Bauer 4

High modified Bauer score BUT

1. CANNOT ambulate2. Low albumin

32% survival

Modified Bauer Score

(4): 59% survival

Case 2:Bauer 4

Ghori et al 2015

Modified Bauer Score (4): 59%

No additional heath states: 30 %

Modified Bauer Score (4): 59%

Intact Ambulation/Normal albumin: 78 %

Ghori et al 2015

30% Vs. 78% survival: big difference !Capture patient health state Tell apart patients predict survival reliably

Our Model: Advantages Simple to apply.

Superior to existing models in predicting survival.

300 patients in our analysis: one of the largest cohorts in literature.

Our Model: Limitations

Retrospective nature of our data.

Model developed from surgical patients so may not be extrapolated to non-surgical patients.

Future Direction

Studies to validate our model by applying it to: Different databases. Prospectively studying it.

Managing Spine Metastases

Where did we come from?

Where are we going?

Historical: No benefit with Surgery

Present : Surgery – too much ? Who to operate on?

Our Model

Future approach: Improve patient selection

Operate on the RIGHT PATIENT

Evolution of spinal

instrumentation

Include Patient “Health State”

Predict survival reliably