再発髄膜腫の病態—再発関与因子と治療予後

Clinical Study on the Recurrence of Meningioma:Correlating factors for the recurrence and therapeutic prognosis of the meningioma

I．はじめに

　一般に髄膜腫は境界明確で，slow growingを示す良性腫瘍であり，手術的に全摘出されれば予後良好とされている．従来，髄膜腫の術後再発に関与する因子として全摘出されたかどうかが重要であるが^{1,6,10,22,30）}，一方，convexity meningiomaでSimpson Ⅰの完全摘出がされても腫瘍再発の報告^5,22,23）がある．このように髄膜腫のbiological behaviorは必ずしも組織学的所見とは一致せず，髄膜腫の悪性度の定義については種々の議論^{1,9,10,12,13,18,20,23）}がある．

　著者らは髄膜腫の手術症例を対象とし，手術後長期追跡調査を行い，手術後の腫瘍再発と関連して年齢，性，腫瘍局在，腫瘍組織型，腫瘍摘出率，腫瘍増殖率としてAgNOR染色，BrdU標識率について検討した．さらに，再発症例の治療内容とその結果，ならびに治療予後についても報告する．

Authors have studied 128 cases of meningiomas which were operated on and examined histologically. 12 cases (11.3%) of 106 cases of the meningiomas fol-lowed up for more than 5 years after surgery had re-currence after the primary operation. The distribution of age and sex, the tumor location, the histologial type, the extent of tumor evacuation and AgNORs counts and BrdU labeling index for the evaluation of tumor proliferation were studied comparatively in the two groups, the recurrent and nonrecurrent meningiomas. 8 cases (19.0%) of 42 cases of the meningiomas in the age-group lower than 50 years old were recurrent cases, whereas 4 cases (6.0%) of 67 cases in the age-group over 50 years old were non-recurrent. Concerning the sex distribution of the meningiomas in our cases recur-rent rate was 20.5% among males and 6.0% among females. The tumor locations of the meningiomas did not correlate significantly with recurrence. The extent of tumor removal demonstrated Simpson grade Ⅰ (47 cases), grade Ⅱ (37 cases), grade Ⅲ (17 cases), grade Ⅳ (5 cases) on primary operation. Recurrence was found in 11 cases (13.1%) of 84 cases operated on by total removal of Simpson grade Ⅰ or grade Ⅱ. 8 cases of 11 cases had recurrence within 5 years after the prim-ary operation of Simpson grade Ⅰ or Ⅱ. Total removal of the tumor was important in order to bring about long survival after operation. But correlation between the extent of tumor removal and recurrence was not able to be recognized. Histologically, all of the malig-nant, atypical and papillary type of meningiomas tre-ated in the primary operations had recurrence. In the benign rneningiomas, 9 cases (16%) of 55 cases of meningotheliomatous-type tumors showed recurrence following operation, and 4 of 9 cases of recurrent me-ningotheliomatous-type tumors transformed, developing into two cases of malignant type and two cases of aty-pical type. AgNORs counts were examined in the 11 cases of nonrecurrent meningiomas, and the 16 oper-ated cases of recurrent meningiomas in the primary and/or subsequent operation. The mean and standard deviation of AgNORs counts were 2.25±0.52 in the nonrecurrent group and 2.72±0.38 of relatively high values in the recurrent group. Between the two groups AgNORs counts differed significantly (p＜0.05). After a follow-up of more than 5 years of 12 cases with recurrent meningioma, 9 patients were still alive and 3 patients had died.

Treatment for recurrent cases was performed mainly by operation in 11 cases, and by radiotherapy with no effect for 3 cases. Long survival was found in cases where recurrent tumors were evacuated totally by op-eration.