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?

Abstract

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.

Evaluating the effectiveness of abbreviated breast MRI (abMRI) interpretation training for mammogram readers: a multi-centre study assessing diagnostic performance, using an enriched dataset

“…Given that breast MRI is much better at detecting high grade, aggressive cancers at a smaller size than mammography [ 2 , 3 , 45 ] and early detection of breast cancer improves survival [ 46 , 47 ], upscaling abMRI provision and augmentation of the current fpMRI interpretation workforce through the development of standardised, effective training and performance evaluation is a priority for the specialty. Prospective feasibility research to investigate current uncertainties around recall rates and rates of image-guided core biopsy, vacuum-assisted biopsy and MRI-guided biopsy will be another necessary research step to enable cost-effectiveness analysis of the use of abMRI as a screening tool and will inform decisions by policy makers about the potential introduction of abMRI into future clinical screening practice.…”

Ethnicity and the tumour characteristics of invasive breast cancer in over 116,500 women in England

“…Tumours with less favourable characteristics are more likely to be diagnosed in the interval between screens than at screening, and this could explain the lower proportion of screen-detected cancers observed in Black Caribbeans and black African women compared to the other groups in the older women. 38,39 Adjustment by screening attendance made little difference to the risks of these tumour characteristics, suggesting that there are intrinsic differences in these tumour characteristic profiles in these older women.…”

Breast MRI: an illustration of benign findings

“… 26 In comparison, only 55% of cancers detected by mammography at incident round are <1.5 cm (29943/54,068). 27 A similar pattern is seen for the proportion of incident round invasive cancers that are node negative for MRI: 10/11 91%, 3 13/14 93% 2 and 14/14 100%, 26 compared with incident round screening mammography: 75–80% node negative. 28 It is also supported by evidence that, for high risk women, screening with breast MRI reduces the incidence of late stage disease.…”