Cancer treatments, including chemotherapy and radiation therapy, give a growth advantage to cells with particular genetic changes in healthy tissue, new research finds.

Researchers from the Wellcome Sanger Institute, University of Cambridge, University College London and their collaborators used DNA sequencing to map mutations in normal esophageal tissue from esophageal cancer patients who had received either chemotherapy, chemotherapy and radiation therapy, or no treatment before surgery.

The results, published in Nature Genetics, show that different cancer treatments changed the landscape of mutations in normal tissue. In particular, combined chemotherapy and radiation therapy led to significantly more normal cells with cancer-related mutations in these patients.