No prediction of recurrence of meningiomas by PCNA and Ki-67 immunohistochemistry

Immunohistochemistry for the expression of the proliferation markers proliferating cell nuclear antigen (PCNA) and Ki-67 was studied in 16 non recurring meningiomas, 11 meningiomas recurring as benign tumors, 6 recurring as atypical meningiomas and in 9 recurring as malignant meningiomas. Non recurring meningiomas were defined in this study as tumors without recurrence at least 8 years after surgery. In addition 16 benign recurrences, 14 atypical- and 12 malignant meningiomas were studied. In each group great variation of labeling indices (LI) = per cent of tumor cells labeled was observed, especially of PCNA LIs. The non recurring meningiomas displayed lower mean LI for PCNA and Ki-67 than did the recurring meningiomas of all groups but the differences were not statistically significant. The same pattern was seen when totally resected tumors were studied alone. Benign-, atypical-, and malignant meningiomas had labeling indices that were related to the grade of malignancy. Only PCNA LIs of atypical- and malignant meningiomas were statistically significantly higher than PCNA LIs of non recurring meningiomas. The study indicates that PCNA and Ki-67 are of minor value as predictors of recurrence of benign meningiomas.