Different assessments of immunohistochemically stained Ki-67 and hTERT in glioblastoma multiforme yield variable results: A study with reference to survival prognosis

Abstract

To investigate a marker of tumor proliferation, Ki-67, and telomerase expression in glioblastoma multiforme and to compare the results of different mainly quantitative assessments, in relation to age and survival rates. Immunohistochemical stainings of Ki-67 and hTERT were evaluated in 39 formaldehyde-fixed, paraffin-embedded surgical samples of glioblastoma multiforme diagnosed during 2004, comprising all specimens with sufficient amount of vital tissue sent to the Department of Pathology during this year. Ki-67 counting and hTERT evaluation was assessed on whole tumor sections and on selected areas within each section. Age and length of survival were analyzed in relation to these parameters. We found that different methods of evaluating the stained sections yielded different results regarding Ki-67, but less marked differences for hTERT. With Ki-67 counting on whole sections (non-selected areas), we found a statistically significant correlation with length of survival. There was no corresponding information in the hTERT assessment. We could also confirm a significant inverse correlation between age and length of survival, as previously published. Our data demonstrate that different methods of Ki-67 evaluation may give markedly dissimilar results. The significant correlation found between survival and one but not with two other methods of Ki-67 assessment, implicate the value of standardized quantification methods. Our data indicate a possible prognostic use of immunohistochemical Ki-67 proliferation index in glioblastoma multiforme.