Distribution of tumor size among four groups of patients using A, bi-dimensional (2D) measurement and B, volumetric (3D) measurement. One outlier measurement in the CCNU 2001-2004 was excluded from the graph of the 3D measurement group to prevent compression of the graph scale. In both 2D and 3D measurement analyses, the average tumor sizes of the CCNU 2009-2015 group were below the average tumor sizes of the entire cohort. CCNU indicates lomustine; 3D, 3-dimensional.