Health networking is in principle a formidable instrument to address many challenges posed by cancer, one of the two most common and most lethal non-communicable chronic diseases. The European Union (EU)’s Beating Cancer Plan foresaw the addition of new health networks to the four already existing European Reference Networks on rare cancers: the Network of Comprehensive Cancer Centres and several networks of expertise (NoEs), which will be shortly deployed on items as complex and poor-prognosis cancers, palliative care, survivorship, personalised primary and secondary prevention, omic technologies, hi-tech medical resources, and cancers in adolescents and young adults. The community of experts of the EU Joint Action, due to build such NoEs, has drafted this ‘green paper’, incorporating 13 open questions, in an effort to foster discussion on some open questions about health networking on cancer in the EU. These affect highly diverse issues such as the following: how gaps in research into the instrument of health networking may be filled; which items lend themselves more to health networking in the EU; what degree of cooperation and harmonisation should be required of EU member states to best exploit health networking and give rise to European networks of national/regional networks; how the idea of subsidiarity may be best interpreted to support health networking in the context of EU treaties, which basically do not include health; how health networks should be funded and with what degree of cooperation between the EU and national levels; whether EU health networks should be shaped as legal entities or could give rise to secondary legal entities, also with a view to fundraising; how health networks should be best shaped to advance cancer research and how the EU regulatory system should be updated to exploit such impulse to health networks, in view of the EU General Data Protection Regulation and the new EU Health Data Space; how artificial intelligence can be exploited today within health networks and to what extent it will be able to overcome challenges such as the current lack of interoperability of electronic health records and the language barrier across the EU; and how health networks should involve patients and their groups, with regard to their formal role within EU health networks as well as their ability to have a say in items such as production of clinical practice guidelines, the design of investigator-driven clinical trials, EU regulatory decisions on medicines and devices, health service data governance, and identification of unmet needs.