King's College London

The study was conducted in collaboration with researchers from the Netherlands and USA, and funded by the global Cancer Grand Challenges. 

DCIS is a breast condition that is often found on mammograms and refers to abnormal cells within a milk duct. Research shows that 75% of women with DCIS that is not treated will not get a future invasive breast cancer. However, due to a lack of predictive tools as to whether these women will go on to develop invasive breast cancer, thousands of women with DCIS undergo unnecessary surgery, radiation and hormone therapy each year.

The team collected 95 pairs of samples from women who had DCIS, were treated, and then later developed invasive breast cancer in the same breast. They analysed whether the cancerous cells had gained or lost critical genes that are known in DCIS and invasive breast cancers.

The results, published in Nature Genetics, reveal that 1 in 5 of invasive cancers were genetically unrelated to the original DCIS, and instead represent new cancers. Therefore, these women would not have benefitted from their previous DCIS treatment.

This study might also help to explain why researchers find it difficult to identify biomarkers that accurately predict the risk of DCIS recurrence. Further research should build on these findings to discover the risk factors for women with DCIS who may be likely to develop either a recurrence or a new form of cancer.