PECAM1 and cancer: A number of endothelial surface markers have been used to examine MVD in malignant tumours, and among the three studies that have assessed the prognostic significance of MVD in anal cancer, one study used factor VIII (Wong et al, 1999) and two studies used the CD31 molecule (Table 7) (Indinnimeo et al, 2001; Nilsson et al, 2006).