胃MALTリンパ腫に対するHelicobacter pylori除菌治療後の経過―内視鏡・EUS像からみた治療効果の予測

Clinical Course of Patients with Gastric MALT Lymphoma after Eradication of Helicobacter pylori―The Value of Clinical Typing Based on Endosonographic Findings

要旨　Helicobacter pylori（H. pylori）除菌後1年以上経過観察できた胃MALTリンパ腫22例を超音波内視鏡（EUS）像により表層型，肥厚型，腫瘤型，混合型に分類し，除菌後の経過を検討した．除菌後の完全寛解（CR）群は15例（68％），不変・増悪（NR）群が6例（27％）であった．1例（5％）は部分寛解（PR）群で経過，1年後にH. pylori再感染・腫瘍再燃を確認し，再除菌を行った．CR群は表層型12例，腫瘤型3例で，除菌後1～15か月，平均4.7か月でCRとなった．再燃例はなかったが，2例で8，12か月後に組織学的再燃が疑われ，別の1例で52か月後にH. pylori再感染を認めた．NR群は肥厚型3例，腫瘤型2例，混合型1例で，全例sm深部以深への浸潤を認めた．腫瘤型2例と混合型1例には経口アルキル化剤単剤療法が有効であった．CR群とNR群の除菌前の所見を比較すると，high-grade成分の有無や臨床病期に差はなく，H. pylori菌量とEUSによる病型（表層型か否か）で有意差を認めた．以上より，胃MALTリンパ腫に対する除菌の効果はEUSを含めた病型評価で予測可能であり，無効例に対しても経口化学療法などの胃温存治療の効果が期待できると結論した．

　The clinicopathological course was investigated in 22 patients with gastric MALT lymphoma who were followed up for more than one year after H. pylori eradication. Based on the findings by pretreatment endoscopic ultrasonography (EUS), cases were classified as either superficial, mass-forming, wall-thickening, or mixed types. During the follow-up after H. pylori eradication, complete remission (CR) was observed in 15 patients (68%), partial remission in one (5%), and no response (NR) in six (27%). Of the 15 cases in the CR group, 12 were classified as superficial type and three as mass-forming type before eradication. These 15 patients achieved CR 1～15 (mean, 4.7) months after eradication. No patients exhibited endoscopic relapse of lymphoma, while the histologic relapse was suspected in two cases, and reinfection of H. pylori was confirmed in another patient. Conversely, the NR group included three cases of wall-thickening type, two cases of mass-forming type, and one case of mixed type. Pretreatment EUS demonstrated the tumor invading the deep portion of the submucosa or beyond in all six cases. Oral monochemotherapy with a single alkylating agent was effective for two cases of the mass-forming type and one case of mixed type. When we compared several clinicopathologic factors prior to eradication between the CR and the NR groups, significant difference was observed only in H. pylori density and the EUS type. Neither the presence of high-grade component, nor perigastric lymphadenopathy, nor clinical stage was different between the two groups. We thus conclude that H. pylori eradication induces CR in most cases of superficial type gastric MALT lymphoma. For NR cases, other non-surgical treatments such as oral monochemotherapy or radiation should also be considered as one of the alternatives.