MIB Index as Predictor of Recurrence in Sporadic Vestibular Schwannomas

OBJECTIVE

Nearly 9.2% of vestibular schwannomas (VS) recur. We evaluate the association of cell proliferative markers like MIB with recurrence in VS.

METHODS

Retrospective data of 144 consecutive patients who underwent surgical excision for sporadic VS between January 2010 and July 2015 were collected. Comparison between groups based on recurrence of VS was done.

RESULTS

The average age of the study population was 43.95 ± 12.86 years with 77 (53.5%) men. The average maximal diameter of VS was 40.25 ± 7.23 mm. Gross total resection was done in 52 (36.1%) patients. While near total resection was performed in 81 (56.3%) patients, the remaining 11 (7.6%) patients underwent a subtotal resection. The mean follow-up period was 37.99 ± 10.09 months (24-60). Recurrence of VS was observed in 18 (12.5%) patients. There was no difference between the groups for diameter of the tumor (42.22 ± 8.04 vs. 39.64 ± 7.00 mm; P = 0.191). The average MIB index value was higher in patients with recurrence of tumor at follow-up (4.78 ± 5.77 vs. 1.89 ± 1.48 mm; P < 0.001). There was no difference between the groups for extent of resection or postoperative complications. MIB was the only significant predictor for recurrence (β = 1.355 (1.07-1.78; confidence interval 95%); P = 0.031). On receiver operating characteristic curves, a cutoff value of 3.5% for MIB showed a specificity of 84.1%.

CONCLUSIONS

MIB index ≥3.5% is associated with recurrence in VS. Maximal diameter of the tumor and extent of resection are perhaps not associated with recurrence of VS.