Supplemental Breast Cancer Screening: A Density Conundrum

Supplemental Screening for Patients at Intermediate and High Risk for Breast Cancer

The sensitivity of mammography is more limited in patients with dense breasts and some patients at higher risk for breast cancer. Patients with intermediate or high risk for breast cancer may begin screening earlier and benefit from supplemental screening techniques beyond standard 2-dimensional mammography. A patient's individual risk factors for developing breast cancer, their breast density, and the evidence supporting specific modalities for a given clinical scenario help to determine the need for supplemental screening and the modality chosen. Additional factors include the availability of supplemental screening techniques at an individual institution, cost, insurance coverage, and state-specific breast density legislation.

An analysis of screen-detected invasive cancers by grade in the English breast cancer screening programme: are we failing to detect sufficient small grade 3 cancers?

OBJECTIVE

Randomised controlled trials have shown a reduction in breast cancer mortality from mammography screening and it is the detection of high-grade invasive cancers that is responsible for much of this effect. We determined the detection rates of invasive cancers by grade, size and type of screen and estimated relative sensitivities with emphasis on grade 3 detection.

METHODS

This observational study analysed data from over 11 million screening episodes (67,681 invasive cancers) from the English NHS breast screening programme over seven screening years 2009/2010 to 2015/2016 for women aged 45-70.

RESULTS

At prevalent (first) screens (which are unaffected by screening interval), the detection rate of small (< 15 mm) invasive cancers was 0.95 per 1000 for grade 1, but for grade 3 only 0.30 per 1000. The ratio of small (< 15 mm) to large (≥ 15 mm) cancers was 1.8:1 for grade 1 but reversed to 0.5:1 for grade 3. We estimated that the relative sensitivity for grade 3 invasive cancers was 52% of that for grade 1 and the relative sensitivity for small (< 15 mm) grade 3 only 26% of that for small (< 15 mm) grade 1 invasive cancers.

CONCLUSIONS

Sensitivity for small grade 3 invasive cancers is poor compared with that for grade 1 and 2 invasive cancers and larger grade 3 malignancies. This observation is likely a limitation of the current technology related to the absence of identifiable mammographic features for small high-grade cancers. Future work should focus on technologies and strategies to improve detection of these clinically most significant cancers.

KEY POINTS

• The detection of small high-grade invasive cancers is vital to reduce breast cancer mortality. • We estimate the sensitivity for small grade 3 invasive cancers may be only 26% of that of small grade 1 invasive cancers. This is likely to be associated with the non-specific mammographic features for these cancers. • New technologies and appropriate strategies using current technology are required to maximise the detection of small grade 3 invasive cancers.

Between-Race Differences in Supplemental Breast Cancer Screening Before and After Breast Density Notification Law

Guidelines recommend supplemental breast cancer screening for women at increased breast cancer risk; however, the passage of breast density notification laws may lead to supplemental screening that is incongruent with women's risk. We examined supplemental screening (ie, MRI, ultrasound, or tomosynthesis within 6 months of screening mammogram) among a sample of 2,764 African American (AA) and 691 European American (EA) women with negative or benign screening mammograms for whom we had data from both before and after implementation of breast density notification laws in the state of Michigan. Results indicated a 5-fold increase (from 0.14% to 0.7% of women) in supplemental screening among screen-negative women after passage of the law, driven in large part by an increase in supplemental screening among AA women. Breast density was more predictive of supplemental screening and had a marginally greater explanatory role in between-race differences in supplemental screening after passage of the law. Subgroup analyses (n = 250) indicated that whereas 5-year breast cancer risk was positively associated with supplemental screening before the law and negatively associated after the law for EA women, 5-year risk was not associated with supplemental screening either before or after passage of the law for AA women. Our findings suggest that whereas passage of the breast density notification laws may have motivated supplemental screening among AA women in particular, it lessened the consideration of breast cancer risk in supplemental screening decision making.