Cancer After Spinal Fusion

BACKGROUND: Bone morphogenetic protein (BMP) is used in tens of thousands of spinal fusions each year. A trial evaluating a high-dose BMP formulation demonstrated that its use may be associated with an increased risk of cancer. OBJECTIVE: To evaluate whether BMP, as commonly used today, is associated with an increased risk of cancer or benign tumors. METHODS: We performed a retrospective study using the Thomson Reuter MarketScan database. We retained all patients who had no previous diagnosis of cancer or benign tumor and had at least 2 years of uninterrupted enrollment in the database before and after their operations. A propensity score--matched cohort was created to ensure greater covariate balance between treatment groups. RESULTS: Within the propensity score--matched cohort (n = 4698), BMP-exposed patients had a nonsignificant increase in the rate of cancer diagnosis (9.37% vs 7.92%; P = .08). After adjustment for covariates, BMP exposure was associated with a 31% increased risk of benign tumor diagnosis (odds ratio, 1.31; 95% confidence interval, 1.02-1.68; P < .05). When the benign tumor diagnoses were stratified by organ type, BMP patients had significantly more diagnoses of benign nervous system tumors (0.81% vs 0.34%; P = .03), and within this group, benign tumors of the spinal meninges were much more common in the BMP-treated group (0.13% vs 0.02%; P = .002). CONCLUSION: The results of this large, independent, propensity-matched study suggest that the use of BMP in lumbar fusions is associated with a significantly higher rate of benign neoplasms but not malignancies.