Cancer-on-a-chip platforms for modeling solid and liquid tumors. (a–c) A microengineered ductal carcinoma in situ (DCIS)-on-a-chip platform. (A) DCIS spheroids embedded in a layer of normal epithelium sitting on top of a stromal microenvironment containing mammary fibroblasts. (b) Cytoxocitiy of the anticancer drug paclitaxel on cells in the DCIS-on-a-chip platform. (c,d) Quantification and confocal images showing the effect of paclitaxel on the progress of the ductal carcinoma spheroids in the DCIS-on-a-chip platform. (e,f) Angiogenesis in liquid tumors. (e) Schemtaic showing biomimetic angiogenesis devices in response to leukemic cells. (f) Confocal images showing directional angiogenic sprouting towards a leukemic channel under different leukemic cell stimulations. Adapted, with permission, from [45] (c,d) and [54] (f).