BackgroundMeningiomas show variable tendency to recur. While risk factors of recurrence have been largely investigated in literature, paucity of data are available on the time to recurrence. To identify main factors affecting the time to recurrence to assist preoperative treatment decision-making strategy and to define a tailored clinical and neuroradiological follow-up. MethodsData of 35 patients with intracranial meningioma recurrences have been retrospectively reviewed. Demographic (patient age at initial diagnosis and sex), radiological (meningioma location, pattern of regrowth and topography of recurrences at first reoperation), pathological (WHO grade and Ki67-MIB1 at initial surgery and at first reoperation, progesterone receptor (PR) expression), and surgical (extent of resection at initial surgery according to Simpsons grading system, number of reoperations) factors were analyzed. ResultsTime to recurrence ranged from 20 to 120 months. Extent of resection at initial surgery was Simpson grade I in 7 patients (20%), grade II in 10 (28.5%), grade III in 14 (40%) and grade IV in 4 (11.5%). Longer median time to recurrence was observed for skull base localization (p<0.01), Simpson grades I and II versus grades III (p=0.01) and IV (p=0.02), values of Ki67-MIB1≤ 4% (p=0.001) and PR>60% (p=0.03); conversely, sex and age, number of reoperations and unchanged/progression of Ki67 and/or WHO grade between first surgery and reoperation did not correlate in statistically significant way with time to recurrence. ConclusionThe extent of resection and the Ki67-MIB1 represent the most important factors predicting shorter recurrence time of intracranial meningiomas. Patients with incomplete (Simpson grades III and IV) resection and high Ki67-MIB1 values, especially at non-skull base localization and with low PR values, need of a closer short-term clinical and radiological follow-up in the first years after surgery.