Proliferative Potential of Malignant Glioma Cells Before and After Interstitial Brachytherapy

放射線組織内照射療法(BRTX)後の再発時に開頭術を施行した悪性神経膠腫30例のうち組織学的に放射線壊死と診断された症例(12例)と腫瘍の再発例(18例)との増殖能を比較検討した。MIB-1抗体にて免疫組織学的染色を行い腫瘍および壊死組織に存在する腫瘍細胞のMIB-1陽性率を検索した。内訳は退形成性星細胞腫14例、神経膠芽腫16例である。放射線壊死の12例中2例は組織は壊死のみで、10例では腫瘍細胞が一部壊死内に混在してみられた。放射線壊死のMIB-1陽性率は7.6±5.5%で、初回手術時のそれ(17.0±11.2%)と比較し有意に低値であった(p<0.05)。腫瘍再発例では、初回時と再発時とで陽性率に差はなかった。以上より放射線壊死組織内に腫瘍細胞がみられるが、これらの増殖能はBRTXにより低下していた。

The viability of tumor cells in radionecrotic tissue after interstitial brachytherapy (BRTX) was evaluated using immunohistochemical markers of proliferative potential in primary and recurrent tumors. Tumor specimens from 30 patients with malignant gliomas (14 anaplastic astrocytomas, 16 glioblastomas) taken before and after BRTX were examined using MIB-1 monoclonal antibody. Histological examination of specimens obtained by craniotomy or stereotactic biopsy after BRTX revealed tumor recurrence in 18 patients and radionecrosis in 12 patients including two with pure radionecrosis and 10 with a mixture of both tumor and radionecrosis. The MIB-1 index of the tumors with radionecrosis was 7.6 ± 5.5%, and that of the primary tumors was 17.0 ± 11.2%, showing a significant difference (p < 0.05). There was no significant difference between the MIB-1 index of the primary tumors with local recurrence after BRTX and the primary tumors which underwent radionecrosis. Although morphologically viable tumor cells were found in the radionecrotic tissue, BRTX causes a reduction in the proliferative potential of these tumor cells.