There is an urgent for a novel approach to cancer research with 1.7 million new cases of cancer occurring every year in the United States of America. Tumor models offer promise as a useful platform for cancer research without the need for animal models, but there remains a challenge to fabricate a relevant model which mimics the structure, function and drug response of human tumors. Bioprinting can address this need by fabricating three-dimensional constructs that mimic tumor heterogeneity, vasculature and spheroid structures. Furthermore, bioprinting can be used to fabricate tissue constructs within microfluidic platforms, forming “tumor-on-a-chip” devices which are ideal for high-throughput testing in a biomimetic microenvironment. Applications of tumors-on-a-chip include facilitating basic research to better understand tumor development, structure and function as well as drug screening to improve the efficiency of cancer drug discovery.