On 16 September 2021, M.C. Agahozo will defend her PhD dissertation, entitled: ‘Exploring the Diversity of Ductal Carcinoma in situ of the Breast; Subtype-specific tumor and microenvironmental characteristics’.

Since the introduction of population screening by mammography, over 20% of all breast cancers is diagnosed as ductal carcinoma in situ (DCIS), which accounted for only 5% three decades ago. DCIS is considered a non-obligate precursor of invasive breast cancer (IBC) and it is treated as such, with respect to local therapy. However, some DCIS lesions will remain indolent while others will progress into IBC. In order to understand DCIS behavior, several classifications have been proposed. Morphological grading, which is based on nuclear atypia, is the widely used method for DCIS classification. However, immunohistochemical surrogate subtypes, based on the expression of the estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2), are increasingly used in DCIS research. Currently, none of these classifications is able to predict DCIS behavior. The aim of this thesis was therefore to identify novel internal (restricted to DCIS cells) and environmental markers that could contribute to DCIS behavior.

The PhD defences do not take place publicly in the usual way in the Senate Hall at campus Woudestein or in the Professor Andries Querido Room at the Erasmus MC. The candidates will defend their dissertation either in a small group or online.