The glandular volume of the breast could be a more important indicator than breast density to predict the risk of breast cancer
Fibroglandular tissue, which looks white on mammography, is made up of cells, fibrous tissue and extracellular elements, essentially collagen. The ratio between the amount of fibroglandular tissue with respect to breast volume is called breast density. It varies from one woman to another for genetic reasons and personal history, and changes fundamentally with age and body mass index. Since the 1970s, this value has been studied very closely, since it is known that, apart from "being a woman", having a high breast density is the most prevalent risk factor for the development of breast cancer in the population. But the methods that exist to measure breast density and study the changes that occur in that area over time have limitations, both qualitatively and quantitatively, making it difficult to make an accurate assessment.
For this reason, a group of experts of the Image Gynaecological Diagnosis Service of Dexeus Mujer, led by Dr Jean Browne, has carried out a retrospective cross-sectional study based on the analysis of mammograms performed on a total of 32,448 patients aged 40 and older that perform their annual review in the centre, in order to describe the relationship between the values recorded in breast density, glandular tissue volume and total breast volume and age, throughout of a period of 20 months of follow-up in a clinical setting (from 1 April 2014 to 31 December 2015) in healthy women, as well as to observe the differences in these parameters in women diagnosed with breast cancer in the studied period.
The study has only taken into account the woman's age when assessing breast density, but not other related aspects, such as the body mass index, the age at which she was a mother for the first time, the number of children, family or personal history or the intake of hormonal medication. The analysed values were those recorded through the photon counting technology which offers high precision in the parameters’ measurement. This technology allows mammography to be performed using a very low dose of radiation to the breast, approximately half that of other systems, and to measure the parameters simultaneously (without additional radiation).
The results reveal that breast density decreases with age, both in women who have been diagnosed with breast cancer and in healthy women. But regardless of age, breast density and glandular tissue volume are generally higher in women with cancer. They also indicate that glandular tissue volume could be a more important indicator than breast density when predicting the risk of breast cancer, since this parameter is the one that presented a more significant difference (on average 24% more abundant in women with cancer).
Likewise, the study authors indicate that the precision and simplicity to acquire data from photon counting technology can set the stage for future interventions to reduce breast density or glandular volume of the breast, with the ultimate goal of reducing the incidence of breast cancer.
Browne JL, Casas L, Santandreu G, Rodriguez I, Navarro B, Tresserra F, Pascual MA.
Breast Cancer Res Treat. 2019 Nov 27; doi: 10.1007/s10549-019-05502-7.