Proliferative potential of recurrent intracranial meningiomas as evaluated by labelling indices of BUdR and Ki-67, and tumour doubling time.

This study was designed to provide the reciprocal relationship among labelling indices of 5-bromodeoxyuridine (BUdR LI), Ki-67 (Ki-LI), and tumour doubling time (Td) of recurrent meningiomas. In our series of 182 primary intracranial meningiomas, 46 cases recurred. The average of BUdR LI and Ki LI for nonrecurrent meningiomas were 0.77 +/- 0.13% and 4.71 +/- 1.96%, respectively. Recurrent meningiomas had significantly higher LIs at the first operation: BUdR LI was 3.77 +/- 1.22% and Ki LI was 14.78 +/- 3.17%. The recurrent ratio significantly increased with the degrees of each LI. And the linear regression analysis has demonstrated a significant correlation between BUdR and Ki LI. Td was calculated accurately by NIH, a computer software. Td showed a significant inverse correlation with each of the labelling indices. Consequently, BUdR, Ki LIs and Td of individual tumours correlate mutually well. Of the 46 recurrent cases, 4 received radiation after the operation. Td of the irradiated meningiomas tended to be longer than expected for their higher level of BUdR and Ki LIs before radiation therapy. Thus, it was shown that the radiation therapy delays the regrowth of meningiomas.