Cancer Research UK has a series of 7 grand challenges detailed on its website

Challenge 1: Develop vaccines to prevent non-viral cancers

Challenge 2: Eradicate EBV-induced cancers from the world

Challenge 3: Identify new targets for cancer prevention by understanding how unusual patterns of mutation are induced by different cancer-causing events

Challenge 4: Distinguish between lethal cancers that need treating, and non-lethal cancers that don’t

Challenge 5: Map the molecular and cellular tumour microenvironment in order to define new targets for therapy and prognosis

Challenge 7: Deliver biologically active macromolecules to any and all cells in the body to effectively treat cancer

Well worth reading about and there is also the opportunity to suggest your own challenge.