画像診断による化学・放射線療法の原発巣の効果判定―胃悪性リンパ腫

Response Assessment for the Primary Gastric Lymphomas: Usefulness of Endoscopic Evalution

要旨　当院で初回治療を行った胃悪性リンパ腫42例における内視鏡的CRまでの期間中央値は，胃MALTリンパ腫21例では282日であり，胃DLBCL 21例では292日であった．治療前CTによる胃病変もしくは腫大リンパ節（長径＞1cm）の認識は16/42例（38.1％）でのみ可能であった．認識しえた16例にCTを主体とした効果判定（以下，CT判定）を行ったところ，CTでは治療後早期に病変認識が困難となるため，CT判定CRまでの期間は胃MALTリンパ腫の3/3例（100％）で111日，胃DLBCLの11/13例（84.6％）で101日であった．しかし，CT判定CRと同時期の内視鏡では8/14例（57.1％）に内視鏡的かつ病理組織学的な腫瘍残存を認めた．内視鏡的効果判定はCTで認識困難な病変の変化をとらえ，病理組織学的検証が可能な点からも有用な効果判定法と考えられた．

　We treated 42 patients with malignant lymphomas as initial therapy from September 2002 to January 2009. Endoscopic complete response（CR）was achieved for 282 days（median）in 21 of the 21 patients（100％）with gastric MALT（mucosa-associated lymphoid tissue）lymphoma and was achieved for 292 days in 20 of the 21 patients（95.2％）with gastric DLBCL（diffuse large B-cell lymphoma）. Thickening of the gastric wall or enlarged lymph nodes（＞1.0cm in the longest transverse diameter）before therapy due to involvement by lymphoma was detectable in only 16 of the 42 patients（38.1％）by computed tomography（CT）scan. We assessed the treatment response of these 16 cases with CT according to the international working group response criteria. CR with CT was achieved for 111 days in 3 of the 3 patients（100％）with gastric MALT lymphoma and was achieved for 101 days in 11 of the 13 patients（84.6％）with gastric DLBCL. Time to CR with CT was much shorter than time to endoscopic CR because of the early decrease in size of all the detectable lesions. But It was revealed histologically by endoscopic evaluation with biopsy that residual lesion was present in 8 of the 14 patients（57.1％）at the same time as CR with CT. It is likely that response evaluation by endoscopy with biopsy is useful because of the detectavility of the lesion and availability of histological evaluation.