Acoustic tumor growth: implications for treatment choices.

Background: Knowledge of acoustic neuroma (AN) growth is essential for treatment planning.

Methods: A retrospective analysis of 119 patients with AN (mean age, 65 years; range, 37-84 years) followed with interval magnetic resonance imagings (MRIs) was performed. Change in maximum tumor dimension as a function of follow-up period was analyzed.

Results: Overall, maximum tumor dimension increased >2 mm in only 30% of patients. Of those that grew, the mean growth rate was 3.8 mm/year (maximum, 25 mm/year). Age, gender, and laterality did not predict growth. Most tumors that grew (86.1 %) were <20 mm at presentation. However, tumors >20 mm were statistically more likely to grow (71%, p =0.028).

Conclusions: Most ANs followed with periodic MRIs do not grow. Available clinical information usually cannot predict growth. Serial MRIs are advocated for all patients treated with observation.