Erratum to: J Neurooncol (2013) 115:277–283 DOI 10.1007/s11060-013-1227-y

Unfortunately, the representation of certain data published in the original article has had to be updated to fully meet requirements of the Agency for Healthcare Research and Quality (AHRQ). The data in question are now represented as ‘≤ 10’ (in Table 2). For citation purposes, please refer to the corrected version.