1p/14q co-deletion: A determinant of recurrence in histologically benign meningiomas.

Background: Meningiomas are the most common benign central nervous system tumors. However, a sizeable fraction recurs, irrespective of histological grade. No molecular marker is available for prediction of recurrence in these tumors. Materials and Methods: We analyzed recurrent meningiomas with paired parent and recurrent tumors by fluorescence in situ hybridization for 1p36 and 14q32 deletion, AKT and SMO mutations by sequencing, and immunohistochemistry for GAB1, progesterone receptor (PR), p53, and MIB-1. Results: 18 recurrent meningiomas (11 grade I, 3 grade II, 4 grade III) with their parent tumors (14 grade I, 2 grade II and 2 grade III) were identified. Overall, 61% of parent and 78% of recurrent meningiomas showed 1p/14q co-deletion. Notably, grade I parent tumors showed 1p/14q co-deletion in 64% cases while 82% of grade I recurrent tumors were co-deleted. AKT mutation was seen in two cases, in both parent and recurrent tumors. SMO mutations were absent. GAB1 was immunopositive in 80% parent and 56.3% recurrent tumors. MIB-1 labeling index (LI), PR and p53 expression did not appear to have any significant contribution in possible prediction of recurrence. Conclusion: Identification of 1p/14q co-deletion in a significant proportion of histologically benign (grade I) meningiomas that recurred suggests its utility as a marker for prediction of recurrence. It appears to be a better predictive marker than MIB1-LI, PR and p53 expression. Recognition of AKT mutation in a subset of meningiomas may help identify patients that may benefit from PI3K/AKT pathway inhibitors, particularly among those at risk for development of recurrence, as determined by presence of 1p/14q co-deletion.