Risk Classification According to miettinen and lasota Table 1 Risk Stratification of Primary GIST by Mitotic Index, Size, and Site* Tumor Parameters Risk of Progressive Disease*(%) Mitotic Index Size Gastric Duodenum Jejunum/leum Rectum ≤5per50hpf≤2cm None(0% None(0%) None(0%) None(0%) s5 per 50 hpf >2s5cm Very low(1.9%) Low(4.3%) Low(83%) Low(8.5%) s5 per 50 hpf >5s cm Low(3.6%) Moderate(24%)(Insuff. data (Insuff. data) ≤5per50hpf>10cm Moderate(10%) gh52%) Hgh(34%) High(57%) >5 per 50 hpf Nonet light (Insuff. data) High(54%) >5 per 50 hpf >2s5cm Moderate(16%) High (73% High(50%) Hgh(52%) >5 per 50 hpf >5s 10 cm High(55%) High(85%) (nuff data (nuff. data) >5 per 50 hpf >10 cm Hgh(86%)Hgh(90%) Hgh(86%) High (71%) Too few cases Miettinen Lasota. Semin Diagn Path ol. 2006, 23: 70-83