Supratentorial Astrocytoma Grade IIの治療成績

Clinical Results of Supratentorial Astrocytoma Grade II

I．はじめに

　星細胞腫（astrocytoma）は形態学的によく分化し異型性に乏しいため，組織学的には良性グリオーマとして位置づけられている．しかし，いかによく分化し増殖速度が緩やかであっても，多くは脳実質を浸潤性に発育するため手術による全摘出が困難であり，経過中にしばしば悪性転化を来たすことなどから，臨床的には良性とは言い難い場合も多い^6,12）．また，発症年齢，発生部位が広範で，その生物学的性状も症例により大きく異なることなどから，治療に関しては統一された見解がないのが現状である^13,17）．その要因として，星細胞腫は全体としては脳腫瘍の中で比較的高頻度を占めるにも関わらず，臨床上の諸因子，組織診断などにより母集団を均一化すると，なかなか評価するに足る十分な症例数が得られないことなどが考えられる^7,16）．

　従来行われてきた治療は，経過観察から手術・放射線・化学療法の集学的治療まで，報告により様々であり^3,6），その予後決定因子として，年齢，手術摘出度，術前performance statusがいずれの報告でもあげられている^{5,17,19,26）}．総じてWHO分類のgrade Iの場合は手術のみで経過観察，grade IIの場合，全摘出例は経過観察，残存例は放射線を追加というのが最も一般的のようであるが^1,21），放射線治療の有効性に関しては，いまだ意見は大きく分かれている^12,13,26）．

At present, there is no concensus concerning the treatment of low-grade gliomas. The authors conducteda retrospective review of surgically treated, histologically verified cases of supratentorial astrocytomas ofgrade II to evaluate the results of current treatment methods. Thirty-seven patients, 23 males and 14females, treated from April, 1977 through March, 1997 were analyzed. Median patient age was 36 years(range 2-69 years). All patients were diagnosed by surgical specimens. Thirty were fibrillary, and threewere gemistocytic astrocytomas. There were 13 total resections, 7 subtotal resections, 10 partial resections.Of the remaining 7, diagnosis was obtained by stereotactic biopsy. Twenty patients were irradiated andtwo received chemotherapy.

Follow-up information was obtained for 33 patients. The follow-up time ranged from 4 months to 246months (mean, 9 years). Overall survival rates at 5 and 10 years for the entire treated group were 71% and57% respectively.

Total and subtotal resections were significantly associated with longer survival time, the 5- and 10-yearsurvival rates were 93% and 67%, respectively. They were 40% and 40% in patients with partial resection orneedle biopsy. Patients with gemistocytic astrocytoma had a poor prognosis with a median survival of 44.5months. The influence of radiotherapy was not obvious:92 and 69% of patients were alive at 5 and 10years respectively without radiotherapy. The extent of surgery and histological type were by far the mostimportant factors in predicting length of survival. The importance of an accurate histologic diagnosis and agross total resection is emphasized.