|The picture shows how obesity lead to stiffened material |
surrounding fat cells in breast tissue, which can create
ideal conditions for tumor growth.
(Credit: Cornell University)
Women who are obese have a higher risk and a worse prognosis for breast cancer, but the reasons why remain unclear. A new study published in Science Translational Medicine explains how obesity changes the consistency of breast tissue in ways that are similar to tumors, thereby promoting disease.
The study of mice and women shows obesity leads to a stiffening of a meshwork of material that surrounds fat cells in the breast, called the extracellular matrix, and these biomechanical changes create the right conditions for tumor growth.
The findings suggest clinicians may need to employ finer-scale imaging techniques in mammograms, especially for obese women, to detect a denser extracellular matrix. Also, the results should caution doctors against using certain fat cells from obese women in plastic and reconstructive breast surgeries, as these cells can promote recurring breast cancer.
Fat tissue in obese women has more cells called myofibroblasts, compared with fat tissue in normal-weight women. Myofibroblasts are wound-healing cells that determine whether a scar will form. All cells secrete compounds to create an extracellular matrix, and they remodel and grab onto this meshwork to make tissue. But when myofibroblasts make an extracellular matrix, they pull together - the action needed to close a wound - stiffening the tissue.
But "these are cells in our body regardless of injury," the researchers said. In obese women, there are more myofibroblasts than in lean women, which leads to scarring and stiffening without an injury in the extracellular matrix. Tumors also recruit more myofibroblasts than are found in healthy tissue, which also leads to stiffer extracellular matrix.
Many obese women get regular mammograms but signs of disease don't show up because detecting their dense extracellular matrix between the fat cells requires a finer-scale resolution. The findings "may inspire use of higher resolution imaging techniques to detect those changes," the researchers said.
During plastic or reconstructive surgery following mastectomy in breast cancer patients, doctors may inject adipose stromal cells from obese donors to regenerate tissue. "What our data suggests is that it is really important where these cells are being taken from," the researchers said. "If you use these cells from an obese patient, they are very different and you may actually be driving malignancies if you implant them."
Based on material originally posted by Cornell University.