106 Quick summary: By analysing nearly 2,800 genomes, researchers have identified eight new DNA pattern signatures specific to breast cancer that reveal how structural genomic changes interact with the tumour immune microenvironment. This detailed breakthrough allows scientists to differentiate the distinct genetic effects of specific mutations, offering a far more precise method to identify deficiencies and match patients with targeted therapies. These findings carry vital implications for oncology and clinical healthcare practice, providing a foundational framework and an open access visualiser tool to accelerate personalized medicine and improve long term survival outcomes. A study led by Dr Jason Pitt, Principal Investigator at the Cancer Science Institute of Singapore (CSI Singapore) at the National University of Singapore, has identified eight new “signatures” of DNA patterns (gains and losses) in breast cancer. By analysing nearly 2,800 genomes, the team systematically profiled changes in the number of DNA copies in breast cancer, with the goal of better understanding the underlying mechanisms of tumour development and evaluating how these structural genomic changes relate to clinical outcomes. The identified signatures could help refine future diagnostic tools, as well as better match breast cancer patients with targeted therapies. While genomic instability is a hallmark of cancer, previous research often relied on broad patterns that apply across many different types of the disease. This new study, published in Cancer Research on 14th May 2026, specifically examined breast cancer genomes from The Cancer Genome Atlas (TCGA) and METABRIC, both of which are open-access databases. The research team was able to break down known, broad genetic signatures into more detailed, disease-specific categories, revealing a complex interaction between genome instability and the tumour’s immune microenvironment. The study identified eight de novo (newly extracted) DNA gain and loss signatures specific to breast cancer. It differentiated the distinct genomic effects of BRCA1 and BRCA2 mutations and observed that patients with relatively stable (“quiet”) genomes and low macrophage infiltration tended to have better survival outcomes. These identified signatures could help refine future diagnostic tools, such as improving the detection of homologous recombination deficiency, to better match patients with targeted therapies like PARP inhibitors. To ensure these findings benefit the wider scientific community, the researchers launched the CNA Visualiser. This open-access web tool allows scientists worldwide to interact with and visually explore the massive dataset of various cancer genomes. The development of this extensive framework and web portal provides vital biological insights into breast cancer and genomic instability, supplying the necessary tools for future studies across various cancer types. The next phase of this research will focus on validating these genetic signatures in clinical settings to assess their reliability in predicting patient responses to targeted therapy. Additionally, Dr Pitt and his team plan to further explore how the interplay between genome instability and the tumour microenvironment influences long-term clinical outcomes.