Reconstructing tumor tissues in 3D: From organoids to bioengineered niches.

Tumor tissue engineering, integrating organoid, microfluidic, and biofabrication technologies, has opened new avenues for cancer research. Leveraging advanced bioengineering and biomaterials, these 3D models capture tumor architecture, cellular heterogeneity, biomechanics, and biochemical characteristics for disease modeling. Despite recognition that tissue organization influences malignancy and drug resistance, clinically oriented 3D approaches are rare, largely due to tumor microenvironment complexity, cellular plasticity, and interpatient heterogeneity. With a primary emphasis on gastrointestinal malignancies, we outline the capabilities and remaining limitations of organoid-based cancer models, including developmentally defined stem cell-derived systems that enable controlled early-stage modeling when premalignant material is scarce. We discuss patient-derived organoids as clinical avatars for therapy response prediction and summarize recent clinical trials that delineate key bottlenecks hindering routine implementation. Finally, we outline how innovations in biomaterial design, biofabrication, and microfluidics, benchmarking against patient data, and artificial intelligence are converging to better reconstruct tumor complexity, improve experimental tractability, and accelerate translation.