Even though dense breast tissue is a risk factor for breast cancer, researchers from the University of Eastern Finland and Kuopio University Hospital found that very low breast density is associated with a worse prognosis in breast cancer patients.

According to the researchers, the established prognostic factors in breast cancer are tumor size and differentiation grade, spreading to armpit lymph nodes, hormone receptor status, and the more-than-normal amount (positivity) of the HER2 gene.

For the study, researchers examined the prognostic value of mammographic breast density (MBD) and tumor features to determine their relationship with the already established prognostic factors in 278 breast cancer patients.

The team discovered that patients had a lesser chance of survival if they had lower breast density and high amounts of hyaluronan in the tumor — a molecule that is naturally found in almost all breast tissue.

Amro Masarwah, MBBS, presented the results in his doctoral thesis and said in a statement that the findings suggest that dense breast tissue has a more favorable prognosis. Also, as measuring density becomes more common, a physician’s expertise with density can increase and open doors for MBD to be used in the patient’s outcome prediction.

The Nottingham Prognostic Index is a method for calculating breast cancer prognosis that is based on size of lesion, lymph nodes, and grade of the tumor. In order to build off that system and give it a higher predictive power, the researchers created a new index called the Kuopio-Nottingham Prognostic Index, that adds breast density and HER2 positivity to the equation.

“Mammographic breast density is readily available, and can be easily measured and recorded at the time of diagnosis,” said Masarwah. “Given the right training, excellent inter-reader agreement can be achieved and accurate measurements performed without the need of additional complicated, expensive and time-consuming software or procedures.”

In March of last year, the university published a study on very low mammographic breast density leading to worse prognosis of breast cancer patients. Compared to women with high breast density, women with very low-density breasts lived significantly shorter. From the study, 70.6 percent of women with very low breast density were alive at the end of a six-year follow up, while 87.7 percent of women whose tissue proportion was higher than 10 percent were still alive.