Review: Association between breast cancer, breast density, and body adiposity evaluated by MRI
W. Zhu, P. Huang, K.J. Macura, D. Artemov 2015
This study investigated the relationship between age, body adiposity and breast density as assessed from retrospectively obtained 3D MRI images. Adiposity was measured as the upper layer of abdominal adipose tissue; this and age were correlated to incidence of invasive carcicoma (IC) or ductal carcicoma in situ (DCIS).
The chief finding—that breast density not being a predictive factor of breast cancer—is in conflict with previous studies. However, this may be explained by the subject selection in the current study. Due to insurance limitations in the US, MRI scans are only offered to women at high risk of breast cancer. Therefore, the only subjects included had a family history of the disease, carried a high risk mutation (BRCA1/2) or displayed benign breast lesions. These are strong risk factors that could be dominant drivers of disease development in the study cohort; however, they are only present in a minority of people and this calls into question the applicability of these findings to the general population. This, in combination with a lack of indication of how risk factors were distributed between the cases and controls could lead to a limitations in analysis.
A point of interest in this investigation was the use of a direct measure of body adiposity. While BMI is often used as a surrogate measure of adiposity, it is confounded by other factors (such as muscle mass). This move away from BMI could mark an interesting change in terms of using direct measures of fat to predict breast cancer risk.