Low-Dose Digital Mammography May Be Accurate

Research by Chen et al suggests that low-dose techniques for digital mammography may be feasible, as results are not substantially affected by variations in radiation dose. Their study was published in Radiology.

The researchers analyzed retrospectively a cohort of women from the American College of Radiology Imaging Network Pennsylvania 4006 trial. All patients underwent breast screening with a combination of dose protocols, including standard full-field digital mammography, low-dose digital mammography, and digital breast tomosynthesis. A total of 5832 images from 486 women were analyzed with fully automated software for quantitative estimation of density.

Clinical Breast Imaging Reporting and Data System (BI-RADS) density assessment results were also available from the trial reports. The influence of image acquisition radiation dose on quantitative breast density estimation was investigated with analysis of variance and linear regression.

Radiation dose of image acquisition did not significantly affect quantitative density measurements, with percent density demonstrating a high overall correlation between protocols. However, differences in breast percent density were observed within high BI-RADS density categories, although they were significantly correlated across the different acquisition dose levels.

The authors concluded that reproducibility of automated breast density measurements with digital mammography are not affected by variations in radiation dose; thus, the use of low-dose techniques for the purpose of density estimation may be attainable.

Tailoring Screening Mammography

Research by Trentham-Dietz et al published in the Annals of Internal Medicine recommends that frequency of screening for breast cancer should be based on well-recognized risk factors.

The researchers who were breast-cancer epidemiologists and cancer modelers combined data-collection and conducted simulation modeling using national data for incidence, breast density, and screening performance.

It is an accepted fact that screening benefits and overdiagnosis increase with breast density and relative risk (RR) while false-positive mammograms and benign results on biopsy decrease with increasing risk.

Among women with fatty breasts and an RR of 1.0 or 1.3, breast cancer deaths averted were similar for triennial versus biennial screening for both age groups (50 to 74 years, median of 3.4 to 5.1 vs. 4.1 to 6.5 deaths averted; 65 to 74 years, median of 1.5 to 2.1 vs. 1.8 to 2.6 deaths averted).

Breast cancer deaths averted increased with annual versus biennial screening for women aged 50 to 74 years at all levels of breast density and an RR of 4.0, and those aged 65 to 74 years with heterogeneously or extremely dense breasts and an RR of 4.0. However, harms were almost 2-fold higher.

Triennial screening for the average-risk subgroup and annual screening for the highest-risk subgroup cost less than $100 000 per quality-adjusted life year (QALY) gained which is a value for money of medical interventions.

The authors concluded that average-risk women older than 50 without dense breasts should undergo triennial screening while higher-risk women with very dense breasts should receive annual mammograms.  Such frequency and tailoring of screening mammography will maintain a similar or better balance of benefits and harms than average-risk women receiving annual or biennial screening.