sm胃癌の内視鏡診断

Endoscopic Findings of Early Gastric Cancer with Submucosal Involvement

　早期胃癌の予後はm癌とsm癌では明らかな相違があり¹⁾，更に進行癌では予後は著しく低下する．したがって今までに胃癌の深達度を内視鏡的に行う努力が数多くなされてきた^2)～6)．近年，この胃癌の浸潤範囲と深達度の診断が特に重要視されるようになり⁷⁾，深達度診断は91.8％可能であったとの報告⁸⁾もみられている．

　しかし，現実には深達度の内視鏡診断はかなり難しく，長年の経験に負うところが多い．したがってこの弊害をなくし，経験の浅い人たちにも正しく深達度診断を可能とするためには深達度診断に必要な情報を整理し，できるだけ単純化することが重要である．

　In the estimation of invading depth of gastric cancer, three categories such as mucosal cancer, submucosal cancer and advanced cancer are widely applied. Many problems lie on the endoscopic estimation of invading depth. In type Ⅲ or type Ⅲ+Ⅱc of early gastric cancer, active ulceration will sometimes prevent the examiner from diagnosing invading depth of cancer.

　Generally speaking, differentiation between mucosal cancer and submucosal cancer is quite a problem and yet important. On the other hand, advanced cancer especially invading the muscularis propriae (pm cancer) must be strictly differentiated from mucosal cancer and submucosal cancer.

　In type Ⅰ of early gastric cancer, it is almost impossible to estimate invading depth by endoscopic findings. Only the size of polyp suggests invading depth. Large polyps more than 4 cm in diameter had frequently submucosal invasion.

　In type Ⅱa of early gastric cancer, central depression, erosion and/or bleeding on the surface of the elevated lesion could be signs of submucosal invasion. On the other hand, most of elevated lesions with normal surface was mucosal cancer.

　In type Ⅱc of early gastric mucosa, small nodule formation and drumstick formation and/or fusion of interrupted folds at the depressed margins were signs of submucosal cancer. In addition, submucosal invasion was frequently observed in cases with irregular mucosa, multiple erosions with or without bleeding and stiff surface on the depressed mucosa.

　pm cancer (the so-called Ⅱc advanced type) mostly had above-mentioned three signs altogether, e.g., irregular mucosa, multiple erosions and stiffness on the depressed area.

　In cases of simple depression in which mucosal surface is almost the same as other normal part, cancer was limited mostly within the mucosa.