CD68 and gastrointestinal stromal tumor: Previous studies have demonstrated that the amount of CD68+ macrophages (both M1 and M2) was positively correlated with RFS [118, 119] and risk grade of GIST [94, 95], but the ratio of CD163+ macrophages (M2 only) to CD68+ macrophages showed a negative correlation with RFS [118, 119].