Genetic tumor analyses have so far focused on mutations that lead to altered proteins. They are often considered to be the trigger for malignant tumors. The project "Identifying and understanding non-coding mutations in cancer genomes" went an important step further and traced so-called non-coding mutations in cancer cells that do not lead to altered proteins but are located in regions that alter the activity of important cancer genes. Investigations were carried out specifically on tumors of the skin (melanomas) and brain (glioblastomas). Regarding melanomas, a special focus was put on the importance of non-coding mutations in the regulatory regions of the genes TERT and DPH3/OXNAD1. For both genes it was found that the non-coding mutations promote tumor development and can therefore be called "oncogenic" mutations. For gliomas, the oncogenic significance of the non-coding TERT mutations could also be clearly demonstrated. Furthermore, we analyzed deep whole genome sequencing data of a set of oligodendroglioma sample pairs, obtained from primary and matched relapsed samples, with evolutionary models of tumor growth. This study revealed a composition of tumor cell subpopulations, suggestive of ongoing selection of malignant subclones during tumor growth in most cases. We frequently identified distinct predominant subclones under positive selection in primary and recurrent tumors. Ongoing work is directed at estimating the selective advantage conferred by the associated driver mutations.