“Researchers find new way to predict risk of breast cancer in DCIS patients”

The researchers looked at the outgrowth of Ductal Carcinoma In Situ (DCIS), a possible precursor to breast cancer. DCIS consists of abnormal cells in the milk ducts of the breast. In Belgium, it is found in approximately 2,000 patients of the 10,000 breast cancer diagnoses annually, due to the presence of calcium spots that can be seen on the chest X-ray (the mammogram) and may indicate DCIS.

However, so far it is not possible to predict which DCIS will develop into breast cancer and which will not. Therefore, almost all women with DCIS are treated preventively by means of mastectomy or breast-conserving surgery, followed by radiation and sometimes hormone treatment. Tens of thousands of women worldwide are therefore undergoing intensive treatment without benefiting from it, but experiencing the disadvantages.

Avoid overtreatment

To prevent this “overtreatment” in the future, the researchers created a ‘living biobank’ of DCIS cells to better understand how the cells develop into cancer. To do this, the researchers extracted DCIS cells from women’s surgical tissue and placed them in the milk ducts of mice. Subsequently, the growth of the very different DCIS abnormalities was followed for one year. This has already saved a lot of time: in humans, the development from DCIS to breast cancer usually takes ten to twenty years, in mice this time is reduced to one year.

Slightly less than half of the mice developed invasive mammary tumors. The molecular research showed that the presence of a certain protein, the HER2 protein, increases the risk of breast cancer. The presence of the protein to which the hormone estrogen can bind, known from hormone-sensitive breast cancer, actually meant a smaller risk.

Three-dimensional microscopy showed that the human DCIS cells show two different growth patterns that can predict the risk of breast cancer: in most mice that did not develop breast cancer, the DCIS cells had replaced the mouse cells in the milk ducts (‘replacement growth’), while, if breast cancer did develop, the milk ducts were ‘inflated’, as it were, by the DCIS cells (‘expansive growth’).

“The fact that we were able to discover which DCIS populations do or do not lead to breast cancer on the basis of the growth pattern is promising,” says Colinda Scheele of the VIB-KU Leuven Center for Cancer Biology. “If we can also show in human patients in the future which DCIS cells will not develop into cancer, we may be able to save them a lot of physical and mental suffering.”

The research has been published in the scientific journal Cancer Cell.