Researchers in Manchester have been exploring the causes of high breast density – a known risk factor for breast cancer – that could reveal new ways to prevent the disease.

It has been known for a few years that high mammographic density – as found using x-ray based mammography screening – is linked to an increased risk of a woman developing breast cancer. This risk can be reduced by taking drugs such as tamoxifen before cancer occurs, but long-term use can cause side effects.

Breast tissue is a mix of fat, glandular tissue (including milk ducts) and connective tissue. How dense, or bright, a breast appears on a mammogram depends on the exact combination of each of these tissue types in an individual. Scientists are therefore interested in understanding the structure and formation of denser breast tissue in order to find new ways to target it, and prevent breast cancer.

Now a team at The University of Manchester, working with collaboration with the University Hospital of South Manchester, has investigated how areas of high breast density might be formed, using samples taken from patients.

They created a seamless pathway from operating theatre to lab bench that linked surgeons, radiologists, pathologists and biologists, and this teamwork allowed them to probe the structure of their breast tissue samples.

Professor Charles Streuli and Dr Mike Sherratt, who jointly led the research, said: “Our hypothesis was that increases in breast density are caused by the creation of a stiffer, more ordered structure in the underlying connective tissue.”

The group discovered that the collagen fibres in dense breast tissue had been remodelled and reorganised. They found that certain signalling molecules, which control such organisation, were also more prevalent in the denser samples.

“It looks like this remodelling of collagen leads to stiffer breast tissue. We don’t yet understand how the reorganised collagen then goes onto to promote cancer growth, but this was a small study - we’d like to carry out a bigger project to include assessment of tumour tissue too,” added Professor Streuli.

Notes for editors

Paper entitled “Increased peri-ductal collagen micro-organisation may contribute to raised mammographic density” J C McConnell et al. (2016) Breast Cancer Research 18(1):5. doi: 10.1186/s13058-015-0664-2.