Sander B, Cameronb S, Gunawana B, et al. - Researchers analyzed current stratification schemes used to predict risk of recurrence in gastrointestinal stromal tumors (GIST) that use tumor size and mitotic index (MI) by performing regression tree analysis, maximally selected rank statistics, and survival difference analysis with bootstrap sampling on a naïve GIST population of 161 patients with a mean follow-up of 44 months. They observed optimal stratification of the risk of recurrence at the tumor size thresholds of 4–5 cm and 10–11 cm and at mitotic indices of about 5 per 50 hpf and 10 per 50 hpf, respectively. These data validate the canonical thresholds for size and MI used in risk stratification of GIST, but they recommend considering transition regions and variances in the implementation of these thresholds between the different classification schemes proposed in the recent years when classifying GIST.