Obese Women at Higher Risk of Breast Cancer

Obesity leads to biomechanical changes that create the right conditions for tumor growth.

Overweight women have a higher risk of developing breast cancer than their lean counterparts, according to a new study. While the evidence points to a clear correlation between obesity and breast cancer, the reasons for this correlation remain unclear.

A recent study in mice and women found that 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.

Since the findings show a relationship between the consistency of the extracellular matrix and breast cancer, physicians should employ finer-scale imaging techniques in mammograms to detect the density of the extracellular matrix. The results also caution doctors against using fat cells from obese female donors in reconstructive breast surgeries, as these cells could promote recurring breast cancer.

“We all know that obesity is bad; the metabolism changes and hormones change, so when looking for links to breast cancer, researchers almost exclusively have focused on the biochemical changes happening. But what these findings show is that there are also biophysical changes that are important,” said senior author Claudia Fischbach, associate professor of biomedical engineering.

Obese women have more cells called myofibroblasts in their fat tissue than their normal-weight counterparts. Myofibroblasts are wound-healing cells that determine whether a scar will form.

Every cell secretes compounds to form an extracellular matrix; they remodel and grab onto this meshwork to create tissue. Myofibroblasts pull together when making an extracellular matrix, causing the tissue to become stiff.

The cells are present in the body regardless of whether or not you are injured, according to Fischbach. Since there are more myofibroblasts in obese women, their breasts are prone 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.

Because physicians do not use a fine-scale resolution in mammograms, it is difficult for them to detect signs of disease in their dense extracellular matrix.

“The results may inspire use of higher resolution imaging techniques to detect those changes,” Fischbach said. “Right now, people don’t look for stiffer extracellular matrices as a clinical biomarker.”

The future of many obese women is dependent upon the utilization of finer-scale imaging techniques, and with the spread of this latest data, physicians and scientists can work together to achieve this end. Additionally, doctors should cease the use of obese donors’ fat cells in reconstructive breast surgery as this could increase the risk for patients of having recurrent breast cancer.