Very low mammographic breast density is associated with a worsened prognosis of breast cancer, according to a recent study from the University of Eastern Finland.
Researchers found that disease-free survivals as well as overall life expectancies were significantly shorter in women with very low-density breasts when compared to women with high density breast tissue. The lower the breast tissue density, the less fibroglandular tissue there is compared to fat tissue.
Involving 270 breast cancer patients between the ages of 32 and 86 years at Kuopio University Hospital, the study analyzed breast tissue density on the basis of mammographic images obtained at the time of diagnosis. Researchers determined the proportion of dense glandular tissue of the overall breast area and categorized breast tissue density as low when the proportion of glandular tissue was below 25 percent and very low when below 10 percent. The study was a six-year follow-up focusing on the effects of breast tissue density and other mammographic features on breast cancer prognosis.
Results indicate that a very low breast tissue density is an independent poor prognostic factor of breast cancer, regardless of patients’ age, menopausal status or body mass index. Out of the women with very low breast tissue density, 70.7 percent were alive at the end of the six-year follow-up, compared to 87.7 percent of women whose proportion of glandular tissue was higher than 10 percent. Lower breast tissue density was also associated with more aggressive higher grade tumors.
“It is difficult to detect small tumors when screening dense breasts, and this results in a higher occurrence of clinically detectable interval cancers,” said Professor Ritva Vanninen, study author. “In the U.S., it is nowadays mandatory to let patients know if they have dense breast tissue. This allows them to choose whether they wish to have further tests, for example a screening ultrasound.”
She continued, “It could be assumed that dense breast tissue would also be associated with a poorer prognosis in patients with a recently diagnosed breast cancer. However, this was not the case in our study, as low breast tissue density specifically weakened the prognosis.”
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