Researchers from an international team analyzed genetic data from over 118,000 people to understand how certain genetic variants near a key gene (ESR1, which codes for the estrogen receptor) affect breast cancer risk. They discovered five distinct groups of genetic changes at a region on chromosome 6 (called 6q25) that each influence risk for different types of breast cancer. Some variants increased the chances of developing aggressive, estrogen receptor-negative (ER−) tumors, while others were linked to higher risk for hormone-sensitive (ER+) cancers or denser breast tissue, which itself is a known risk factor. Importantly, they also showed that these risk variants don’t just sit silently in our DNA, they affect how nearby genes like RMND1 and CCDC170 are switched on or off in breast tissue, ultimately altering how cells behave and possibly how tumors start or grow.
This groundbreaking research was made possible in part by samples from the Komen Tissue Bank, the only biorepository in the world that collects healthy breast tissue from volunteers. Because researchers had access to normal breast tissue, donated generously by healthy individuals, they could compare gene activity and protein levels across different genetic variants in a way that simply wouldn’t be possible using tumor tissue alone. This unique resource helped scientists confirm that some high-risk genetic variants are linked to lower estrogen receptor levels even in healthy cells (potentially laying the groundwork for cancer to develop). The findings deepen our understanding of breast cancer biology and open the door for more personalized approaches to prevention and treatment.
