脳腫瘍の放射線療法

THE RADIOTHERAPY OF THE BRAIN TUMORS

I．はじめに

　脳腫瘍の放射線治療についての報告は枚挙のいとまがないが，その感受性・適応についての意見は，腫瘍によつてはまちまちなものが見られる。虎の門病院脳神経外科で経験した脳腫瘍照射症例も，過去7年間にかなりの数に上るので，今回は⁶⁰Co照射を中心に3種の脳腫瘍につき症例を集計的に観察して見た。選んだ症例は治療効果を明確にするため，術中・術後死，入院1ヵ月半に満たない末期入院など放射線治療を考慮する余裕のなかつたものを除いた総数374例である。そのうち脳腫瘍に対しては特に治療を行なわなかつたもの30例で，他は種々の減圧処置・試切を含む手術・放射線療法・化学療法のいずれか，またはその組合せの治療を行なつている。手術例は327例（87.4％）である。放射線療法としては病巣線量2,000R以上を有意義とし，それ以下のものを除いた。効果判定の基準としては脳圧亢進症状改善を含む除痛効果・意識改善を含む神経学的所見の改善・延命効果（生存期間）の3点を主限とした。

Of the verified 96 cases of intracranial gliomas treated at Toranomon Hospital, 74 cases were irradiat-ed by more than 2,000 R ⁶⁰Co.

A review of the series, all postoperative, at a re-cent follow up shows that the average survival improved about twice in the irradiated cases. Total air dosis with regard to survival time allows no conclusive tendency. The same review seems to prove the efficacy of gamma radiation therapy on the increased intracranial pressure more than on the neurologial symptoms. It is also revealed that radio-therapy falls off in its efficacy with the repetition of the therapy. Considering the 11 cases of metas-tatic brain tumors in which intracranial foci may have been fatal, we find that the average survival since the first manifestation of the neurological symptoms were also improved about twice with postoperative radiotherapy.

The average duration in effects of suppressing the intracranial pressure in irradiated patients is, moreover, six times as much as in ones without it. On the efficiency of radiotherapy, the same is pos-sibly true of the 19 patients with craniopharyngio-mas. In this series the average survival is 57 months in the cases with radiation and 27 months without it.

Since our experiences suggest that the sensitivity of a brain tumors to ionizing irradiation varies in efficacy with respective cases and time of treatment, a method of sensitivity test has been devised by means of tissue culture. Fifty percent of degenera-tion rate of cultured cells after 4,000R irradiation in five day culture was taken as a criteria to radio-sensitivity of the tumors. In 14 cultured materials up to the present some were positively correlated to clinical findings and the results are indicative of the possibility of radiosensitivity screening by tissue cul-ture.