This open access book builds on and updates work performed in the HYBRIDA project, funded by the EU to develop an ethical framework for organoid research. Organoids are three-dimensional stem cell constructs that mimic organs of the body or tumours. Patient-derived organoids are envisioned to be grown from individual patients’ tumours and used to tailor the most effective and safest treatments in a new form of personalized medicine.  This text offers a critical assessment of this vision from the perspective of philosophy of medicine. The authors present a tailored “vision assessment”, presented as examples of methodological development, and applied to objects. They first analyse and describe the vision of using organoids for personalized cancer medicine, then critically evaluate this vision and finally comment on ethical implications of the epistemological issues and how to handle them. The authors further draw on sources for empirical inquiries. This book presents an exercise in health technology assessment conducted by philosophers. Its core readership are philosophers of medicine and bioethicists interested in personalized medicine and stem cell research.