Ki-67 index as a predictor of vestibular schwannoma regrowth or recurrence

Ki-67 is a monoclonal antibody that provides a means of evaluating the growth fraction of normal and neoplastic human cell populations. A Ki-67 index of less than 3 per cent is expected for a typical schwannoma. Vestibular schwannomas with an index of greater than 3 per cent are presumed to be actively proliferating and pose a theoretically higher risk for regrowth or recurrence.

A retrospective chart review was conducted. Ki-67 staining was performed and specimens were divided into two groups according to Ki-67 activity: less than 3 per cent (low index), and 3 per cent or greater (elevated index).

Eight patients (53.3 per cent) with elevated Ki-67 had recurrence or regrowth, versus five (8.5 per cent) in the low Ki-67 group. Among the 13 patients with recurrence or regrowth, the average Ki-67 value was 4.3 per cent. Among the 61 patients without recurrence or regrowth, the average Ki-67 value was 1.0 per cent.

The Ki-67 labelling index reliably identifies vestibular schwannomas with an elevated potential for recurrence or regrowth in subtotal or total resection cases. In patients with a Ki-67 index greater than 3 per cent, more frequent clinical examination and radiological follow up are recommended.