In contrast to the strong clinical associations of the tumor invasive front populations, only tumor grade was found to be correlated with the high expression of CD163 at tumor non-invasive front (P < 0.05), while none of clinicopathological factors was found to be correlated with the expression of CD68 at tumor non-invasive front in this study (P > 0.05 for all) (Additional file 1: Table S1). Here, CD68 is linked to neoplasm.