Saturday, 7 August 2010

Is Mammographic Breast Density a Breast Cancer Risk Factor in Women With BRCA Mutations?

In a paper from Sunnybrook in Toronto, Canada in this month's Journal of Clinical Oncology, researchers found that women with increased breast density who were also BRCA gene mutation carriers did not have an increased risk of breast cancer.

Is Mammographic Breast Density a Breast Cancer Risk Factor in Women With BRCA Mutations?
Kavitha Passaperuma, Ellen Warner, Kimberley A. Hill, Anoma Gunasekara, Martin J. Yaffe
Journal of Clinical Oncology, Vol 28, No 23 (August 10), 2010: pp. 3779-3783

Link to Journal  -

Their purpose of the study was based on the knowledge that Increased mammographic breast density is a well recognized as a breast cancer risk factor in the general population. However, it is unclear whether it is a risk factor in women with BRCA mutations. They present the results of a nested case-control screening study investigating the relationship between breast density and breast cancer incidence in this population.

Between November 1997 and March 2008, 462 women (mean age, 44 years; 245 BRCA1 and 217 BRCA2) were screened and 50 breast cancers were diagnosed (38 invasive, 12 ductal carcinoma in situ [DCIS]). Density was not measured in 40 women of whom four developed cancer (three invasive, one DCIS). Mean PD (± standard deviation [SD]) for 376 women who did not develop breast cancer was 34% (23) compared with 31% (21) for 46 women with cancer (P = .51). Logistic regression model of breast cancer incidence and PD revealed an odds ratio of 0.99 (± 0.01 SD) for a one-unit increase in PD (P = .44). Results remained nonsignificant in multivariate analysis, as well as when women with pure DCIS were excluded.

Their conclusion was that ncreased mammographic breast density in "two-dimensional" breast imaging is not associated with higher breast cancer incidence in women with BRCA mutations.

On the basis of these findings, density should not be considered a factor for these women in decision making regarding prophylactic surgery or chemoprevention.

Some pointers they make are that what they call 3D breast imaging like Digital mammography and MRI may give a better reflection of true breast density (compared with conventional mammography (SFM) which tends to over-estimate breast density, may give different results, therefore the study should be repeated with current mammographic techniques using FFDM or using MRI.