CD31 immunostaining was used to assess tumor angiogenesis, and the vascular density in the DHA/MPEG-PCL (7.8 ± 1.48) and DHA (13.4 ± 2.3) groups was significantly lower than that in the NS group (30.8 ± 3.83, p<.01) and the MPEG-PCL group (33.8 ± 3.7, p<.01). This evidence concerns the gene PECAM1 and neoplasm.