Malignant Astrocytoma初期治療後Complete Response症例の検討

Follow-up Study of Malignant Astrocytomas Showing Complete Response after Initial Treatment

I．はじめに

　Anaplastic astrocytoma, glioblastoma multiforme（malignant astrocytoma）の治療成績は依然として満足すべきものではないが，中には長期生存を示す症例が存在する．従来，このような予後良好例の検討により，手術摘出率，年齢，performance status，罹病期間，組織型，腫瘍部位等が予後に対して有意な影響を及ぼすことが報告されてきた^{4,6,11,13,16）}．本研究では，初期治療終了時の画像に注目し，治療後画像上腫瘍の消失を得られたComplete Response（CR）症例の臨床像を検討し，予後判定因子としての有効性を考察した．

The prognosis for patients with malignant astrocyto-mas is still poor. The identification of groups of pa-tients with good prognostic factors should be helpful in selecting the treatment strategies. In general, important prognostic factors are thought to be the extent of sur-gical resection required, age, performance status, dura-tion of symptoms, location, and pathological tumor grade. The purpose of this present study is to evaluate the prognosis of patients with complete response (CR), that is, complete disappearance of the tumor mass in the contrast enhancement of computerized tomography (CT) scan after initial treatment. An additional purpose is to examine the effect of factors such as pathological tumor grade, location, age of patient, and the extent of surgical resection in achievement of CR. The subjects of the study were 81 patients with supratentorial malignant astrocytomas (45 males, 36females) treated with surgical resection and radioche-motherapy in our division since 1980, and followed up for more than 5 years. There were 57 anaplastic astrocytomas (WHO grade Ⅲ) and 24 glioblastomas (WHO grade Ⅳ). The extent of surgical resection and the response to the therapy were evaluated by CT scans. The Kaplan-Meier method was used in generat-ing survival plots.

Twenty-two cases (27%) showed CR at the end of the initial treatment, and the other 59 cases (73%) showed Non CR. Fifteen cases (26%) among 57 grade Ⅲ patients and 7 cases (29%) among 24 grade Ⅳ pa-tients showed CR. Tumor locations of CR cases were exclusively superficial with the exception of one case that involved deep structure. Average age of CR cases and Non CR cases were 34.4 and 49.7, respectively. All CR cases received the gross total resection (more than 95% resection).

Comparing the median survival duration (MSD) in CR cases and Non CR cases (p＜0.001), we found a significant difference. MSD in CR cases was 58 months. 77% of these cases had (2y) 2 year survival periods, and 34% of them had (5y) 5 year survival periods. In contrast to this MSD in Non CR cases was only 11 months, with 26% of the cases having (2y) 2 year sur-vival periods, and only 5% of them having (5y) 5 year survival periods.

The present study provides evidence that CR on CT after initial treatment is an important predictor of lon-ger survival. CR results in significant improvement of the prognosis of supratentorial malignant astrocytomas. Gross total resection is essential to obtain CR. This finding supports the notion that radical surgical resec-tion plays a crucial role in the management of malig-nant astrocytomas.