山口県における脳腫瘍の発生状況について—4年間の集計より

Brain Tumors in Yamaguchi Prefecture : Incidence Through 4 Years

　目的：山口県下の原発性および転移性脳腫瘍の発生頻度を調査する。

　対象：1986年より1989年までの間に山口県内の全脳神経外科施設を受診した山口県在住の脳腫瘍患者726名，うち初発原発性脳腫瘍患者478名（男性207，女性271）。

　方法：年度毎に脳腫瘍Base cardを各施設に配布，集計し，発生率等の検討を行った。骨腫，脂肪腫，頭頸部・皮下・脊髄腫瘍は除いた。

　結果：初発原発性脳腫瘍発生率は7.5人（男性6.8，女性8.1）／10万人／年であった。市郡別発生率では市部と郡部での発生率の差はなかった。日本全国人口構成に基づく人口補正を加えた組織別発生率では神経膠腫が2.1人／10万人／年，髄膜腫が2.1人／10万人／年であり，Rochesterの報告に比し神経膠腫が少なく髄膜腫がやや多かった。日本全国脳腫瘍統計に比べて髄膜腫の割合が多く，神経膠腫，髄膜腫が70代のより高齢者まで多いのが特徴であった。

　結語：本集計は一定背景人口における全脳神経外科施設を受診する患者をもれなく把握できる点で脳腫瘍の発生状況の理解に有意義であると考えられた。

The incidence of brain tumors was studied in Yamaguchi prefecture of about 1,600,000 popula-tion. All of the brain tumor patients admitted to the neurosurgical hospitals in Yamaguchi prefecture were resistered. Cases of osteoma, lipoma, scalp tumor and spinal tumor were excluded. From 1986 through 1989, 726 cases were registered. 135 recur-rent cases were included. Therefore first-diagnosed primary brain tumors were selected to calculate the true incidence.

The number of cases of primary brain tumor was 478 and showed female preponderance (male/ female : 207/271). The incidence of primary brain tumor was 7.5/100,000/year (male/female : 6.8/8. 1) . No difference was present between the incidence in cities and that in rural districts. Percentages of representative tumors were 28.2% for glioma, 32.8% for meningioma, 13.0% for pituitary adenoma and 10.7% for neurinoma. Age-adjusted incidence was 2. 1/100,000/year for glioma and 2.1/100,000/year for meningioma. The incidence of glioma was lower and that of meningioma was higher in Yamaguchi prefecture than those in other reports.

Compared with the Brain Tumor Registry of Japan (1969-1983), the percentage of meningioma cases was large in Yamaguchi prefecture. This difference owed partly to the increased number of population over age of 40's in Yamaguchi prefec-ture. The peak of age distribution was present in age of 50's in Yamaguchi prefecture and in age of 30's and 40's in Brain Tumor Registry of Japan. The peak of age distribution shifted to older ages in Yamaguchi and the difference was conspicuous in age of 60's. This peak consisted of mainly cases of meningioma and partly those of glioma. Other causes were the difference of observation period, the progression of diagnostic capability with CT or MRI, increased number of neurosurgical institutes, or elongation of life span. The Brain Tumor Regis-try of Japan was an extracted study and does not surely express the whole figure.

Our analysis was smaller in case number than Brain Tumor Registry of Japan. It based on almost all cases of brain tumor in Yamaguchi prefecture, therefore it was thought to be valuable for under-standing the true occurrence of brain tumors.