Clinical and epidemiological issues in mammographic density

Abstract

High mammographic density is associated with an increased risk of breast cancer, and of all known breast cancer risk factors has the greatest attributable fraction. Mammographic density is estimated to account for 16% of all breast cancers, but can be altered by endogenous and exogenous hormonal factors, and generally declines with age. Confounding factors such as age, parity, menopausal status and BMI make the interpretation of mammographic density particularly challenging. Furthermore, none of the established means of measuring mammographic density are entirely satisfactory because they are time consuming or subjective. It is hoped that by adding information regarding mammographic density to existing models of breast cancer risk assessment, the accuracy of individual risk assessments can be improved. Although mammographic density has clearly been shown to be a powerful factor for predicting the risk of developing breast cancer, its potential role in assessing hormonal preventive regimens and helping to tailor screening algorithms cannot be fully realized until we have more-precise, simple and reproducible density measures.

Genome wide association study identifies a novel putative mammographic density locus at 1q12‐q21

“…In fact, BMI, a measurement closely related with height, is also associated with MD. 26,27 Another study 28 found that rs11205277 was associated with two stages of height growth, the peak height velocities in infancy (PHV1) and the puberty (PHV2). Moreover Lei et al 29 confirmed the association of this SNP with stature.…”

“…42 The measurement of density was performed visually by a single radiologist using categorical scales and might be considered a limitation. While the use of quantitative methods has been recommended, 27 they are not immune from subjectivity, have been only validated for analog mammograms and underestimate the percentage of density in digital mammograms. 27,43 In our study, three of the seven screening centers used full-field digital images.…”

“…While the use of quantitative methods has been recommended, 27 they are not immune from subjectivity, have been only validated for analog mammograms and underestimate the percentage of density in digital mammograms. 27,43 In our study, three of the seven screening centers used full-field digital images. Furthermore, the use of a single radiologist, with a good intra-observed reproducibility, 19 minimized the measurement error in our study.…”

“…While visual reading evaluates the image as a whole and may overestimate MD, semi-automatic methods compute the percentage of dense tissue taking the whole area limited by the skin into account, including the subcutaneous fat tissue that is not part of the mammary gland. 26,27 This, in turn, may imply a greater agreement between visual assessment and the absolute dense area that is not influenced by the amount of subcutaneous fat.…”

A case‐control study to assess the impact of mammographic density on breast cancer risk in women aged 40–49 at intermediate familial risk

“…Women with a moderate family history of breast cancer may be offered annual mammography from age 40 to 49. 6,7 Mammographic density (MD) is a strong risk factor for breast cancer, both in terms of relative and attributable risk, [10][11][12] in pre-and postmenopausal women. 13 MD reporting using the BI-RADS system is mandatory in many parts of the United States.…”