Washington: A study has indicated that women whose breasts appear dense on mammograms are at a higher risk of breast cancer and their tumours are more likely to have certain aggressive characteristics than women with less dense breasts.
Mammographic breast density--a reflection of the proportions of fat, connective tissue, and epithelial tissue in the breast--is a well-established risk factor for breast cancer.
Women with higher amounts of epithelial and stromal tissue have higher density and higher risk. However, it has not been clear whether breast density was associated with specific tumour characteristics and tumour type.
To explore this issue, Rulla M. Tamimi, Sc.D., at Harvard Medical School and Brigham and Women’s Hospital, Boston, and colleagues, compared breast density in 1,042 postmenopausal women with breast cancer and 1,794 matched control subjects.
They found that the risk of breast cancer increased progressively with increasing breast density.
The associations were stronger for larger tumours than for smaller tumours; for high-grade than for low-grade tutors; and for estrogen receptor-negative than for estrogen receptor-positive tumours.
The link between density and breast cancer also appeared to be stronger for ductal carcinoma in situ (DCIS) than for invasive tumours.
The authors concluded that higher mammographic density is associated with more aggressive tumour characteristics and also with DCIS.
“Our results suggest that breast density influences the risk of breast cancer subtypes by potentially different mechanisms,” they wrote.
“Further studies are warranted to explain underlying biological processes and elucidate the possible pathways from high breast density to the specific subtypes of breast carcinoma,” they added.
The study has been published online in the Journal of the National Cancer Institute.