Researchers may have uncovered how dense breast tissue contributes to cancer development, offering hope for early intervention before tumors form. Breast cancer often emerges in dense tissue, flagged for additional attention after mammograms. The Mayo Clinic notes that dense tissue complicates screening and increases cancer risk. At UC San Francisco, scientists believe they’ve identified the mechanism raising this risk.

Dense tissue’s stiffness attracts immune cells, prompting them to release DNA-mutating chemicals, states a Medical Xpress release. These harmful chemicals damage nearby cells’ DNA, heightening cancer risk. While the medical community has long recognized the link, new research suggests potential preventive measures.

First author Mary-Kate Hayward explained to Newsweek: “The stiffness of dense tissue alters macrophages, which release reactive chemicals that damage local cells’ DNA.” This discovery clarifies dense tissue’s role in cancer development.

The study published in Cancer Cell involved examining breast tumor samples, measuring stiffness, and imaging collagen—identified for making tissues stiffer. Findings revealed that stiffer tumors contained more collagen, scarring, macrophages, and DNA mutations. Elevated STAT3 pathways were also observed, linking stiffness to increased macrophage presence.

Researchers conducted experiments using tumors in gels and mouse models, finding that a stiff environment triggered the STAT3 pathway. This activated signals attracting macrophages, suspecting these macrophages facilitate cancer growth.

“What was striking was that the macrophages were producing chemicals that could travel to nearby cells and damage their DNA,” Hayward remarked to Medical Xpress. “We tend to think of chemicals in the environment as DNA-damaging and cancer-causing. Yet we found macrophages could also produce DNA-damaging chemicals right within the tissue.”

Further experiments confirmed dense breast tissue’s correlation with more macrophages, aldehydes, DNA damage, and advanced disease.

The research team aims to explore drugs that prevent aldehyde formation in macrophages. Hayward expressed hope in Newsweek, noting: “This gives us something to target. If we block these harmful chemicals, we might prevent cancer in high-risk tissue before tumors form.”