Acoustic neuroma/vestibular schwannoma growth: past, present and future.

The growth of vestibular schwannoma (VS) was investigated in a series of 123 patients with 127 tumors in the period 1973 1993. The material was reanalysed and updated 3 years later in 1996. By termination of the first observation period (mean 3.4 years), 94 tumors (74%) exhibited measurable growth, 23 tumors (18%) no measurable growth and 10 tumors (8%) negative growth. By the end of the extended observation period (mean 3.8 years), tumor growth was observed in 104 tumors (82%), no tumor growth in 15 tumors (12%) and negative growth in eight tumors (6%). Several growth patterns were noticed: however, these were not static as the growth patterns of the tumors changed during the extended observation period. Accordingly, the expected growth figures by the end of this century (mean observation period approximately 4 years) will probably be: growth in 111 tumors (87%), no growth in 10 tumors (8%) and negative growth in six tumors (5%). The results indicate that neither the present study nor the previously published studies on tumor growth reflect the natural history of VS, but they only provide information on tumor growth, growth rates and growth patterns during a given observation period.