MKI67 and neoplasm: In contrast, univariable survival analyses identified histology (p<0.001), WHO grading (p<0.001), the Ki-67 proliferation index (cut-offs of 1.6 and 5.0%, respectively) (1.6%, p  = 0.002; 5.0%, p<0.001), the maximum tumor diameter as measured on imaging [cut-off 3.5 cm (median size of tumor) (p  = 0.028)], and the occurrence of cystic tumor parts (p  = 0.015) as critical factors for PFS.