Researchers at MD Anderson reported a cellular atlas mapping the tumor microenvironment surrounding estrogen receptor-positive (ER+) ductal carcinoma in situ (DCIS), a precursor state where many lesions never progress to invasive disease. The atlas integrates samples from normal breast tissue, DCIS, and invasive breast cancer to identify surrounding cells and structures linked to progression. Published in Science, the work aims to clarify why certain preinvasive lesions evolve while others remain indolent. The group said the atlas could help refine risk prediction and support targeted approaches for higher-risk DCIS patients while reducing overtreatment for low-risk cases. The study emphasizes spatial and cellular context as determinants of invasive transition, using a map-style strategy rather than a single biomarker approach.