The field of cancer nanomedicine seeks to overcome the inherent shortcomings of conventional cancer diagnostics and therapies. Yet despite the surge of interest in and attractive attributes of nanotechnologies, challenges remain in their clinical translation, prompting some to argue that they have not yet reached their true potential. In this Viewpoint article, we asked four experts for their opinions on how we can fulfil the great promise of nanomedicine for the detection, diagnosis and treatment of patients with cancer.