Big wars, as bad as they are, often lead to technology breakthroughs. COVID was such a war for biomedicine, which was first decided with the help of the revolutionary technology of synthetic mRNA vaccines. These will now also lead to breakthroughs in cancer research in the foreseeable future. The first vaccines against certain types of cancer are expected to be authorised in the next few years. Clinical trials with larger patient groups are already underway. The purpose of this book is to familiarise medical laypersons with the complex and difficult-to-understand topic of mRNA-based vaccines. It clearly explains how mRNA vaccines, developed in the heated battle against a pandemic, also have the potential to fundamentally change the fight against cancer. Why do they offer such great new opportunities to cure a disease that is still generally considered incurable? Why is everything suddenly happening so quickly - at least by the standards of drug research? Which areas are being researched and where are results most likely to be obtained? And how much longer will it take? Finally, in which other areas can mRNA vaccines still have a beneficial effect? Of course, the specific challenges and problems that are inherent in all drug research are also described. In the end, however, there is a hopeful, positive conclusion that a real breakthrough in cancer therapy is now imminent for the first time.