On the 23rd of February, Dr Johanna Holm defended her thesis entitled “Aggressive breast cancer: epidemiological studies addressing disease heterogeneity”, partly based on Karma samples. In her thesis, Dr. Holm was seeking to increase our understanding of aggressive breast cancer, and how risk factors may be related to it. Her work highlight that interval breast cancers in women with low mammographic density have the most aggressive phenotype, and also suggest disparate genetic backgrounds of screen-detected breast cancers and interval breast cancer. She also show that women at high risk of breast cancer based on genetic and lifestyle factors were significantly more likely to be diagnosed with breast cancer with a favourable prognosis. Her work emphasises that breast cancer subtypes have different aetiologies and highlight the need to identify risk factors separately for distinct breast cancer subtypes and ages of onset.