Colorectal cancer ist the 2nd most leading cancer among men and women in germany. Screening colonoscopy has the potential to detect premalignant lesions. By endoscopical resection of these lesions, colorectal cancers could be avoided. The decision for surveillance is made according to patients medical history, amount and histological characteristics of the resected polyps. Molecular guided decisions are still missing. Thus, further tools and mechanisms, beyond but in addition to endoscopy and histopathological, are strongly required to reduce such interval carcinomas and get a better and deeper inside into molecular alterations which occurs in premalignant lesions in the colon and describe risk populations which might benefit from shorter surveillance strategies by colonoscopy. Therefore GENESIS will enroll 100 patients, which underwent screening colonoscopy with polyp ectomy. All biopsies were stored and processed without formalin in special boxes (PaxGene by Qiagen®). After microdissection of polyp tissue and isolation of DNA targeted next generation sequencing of 38 cancer-related genes followed by bioinformatics and systems biology analyses. The sequencing results were correlated to the endoscopical and histopathological findings. In parallel we are collecting EDTA-blood samples for analysis of circulating cell-free DNA (cfDNA) to investigate the potential of liquid biopsies in premalignant colorectal lesions.