Examining the impact of COVID-19 disruptions on population-based breast cancer screening in Ireland

OBJECTIVE

Many population-based breast screening programmes temporarily suspended routine screening following the COVID-19 pandemic onset. This study aimed to describe screening mammography utilisation and the pattern of screen-detected breast cancer diagnoses following COVID-19-related screening disruptions in Ireland.

METHODS

Using anonymous aggregate data from women invited for routine screening, three time periods were examined: (1) January-December 2019, (2) January-December 2020, and (3) January-December 2021. Descriptive statistics were conducted and comparisons between groups were performed using chi-square tests.

RESULTS

In 2020, screening mammography capacity fell by 67.1% compared to 2019; recovering to 75% of mammograms performed in 2019, during 2021. Compared to 2019, for screen-detected invasive breast cancers, a reduction in Grade 1 (14.2% vs. 17.2%) and Grade 2 tumours (53.4% vs. 58.0%) and an increase in Grade 3 tumours (32.4% vs. 24.8%) was observed in 2020 (p = 0.03); whereas an increase in Grade 2 tumours (63.3% vs. 58.0%) and a reduction in Grade 3 tumours (19.6% vs. 24.8%) was found in 2021 (p = 0.02). No changes in oestrogen receptor-positive or nodal-positive diagnoses were observed; however the proportion of oestrogen/progesterone receptor-positive breast cancers significantly increased in 2020 (76.2%; p < 0.01) and 2021 (78.7%; p < 0.001) compared to 2019 (67.8%).

CONCLUSION

These findings demonstrate signs of a grade change for screen-detected invasive breast cancers early in the pandemic, with recovery evident in 2021, and without an increase in nodal positivity. Future studies are needed to determine the COVID-19 impact on long-term breast cancer outcomes including mortality.

Interval cancer audit and disclosure in breast screening programmes: An international survey

OBJECTIVE AND SETTING

Accurate monitoring of interval cancers is important both for quality improvement and education and is a key parameter of breast screening quality assurance. Issues in relation to communication regarding interval cervical cancer in the Irish cervical screening programme were found, prompting interval cancer process review in all cancer screening programmes. An international survey to examine international consensus on interval breast cancer audit processes was conducted to inform Irish processes.

METHODS

A survey of 24 international population-based breast screening programmes was done to determine which undertook audit of interval breast cancer; if yes, they were asked (1) how they undertake audit, (2) if they obtain individual consent for audit and inform women of audit results, and (3) if disclosure of audit results occurs.

RESULTS

Response was 71% (17/24). Of these, 71% (12/17) have a programmatic audit process to calculate the interval cancer rate (ICR). Of these, ten also carry out radiological reviews, three using a blinded review. Two inform patients that audit is taking place; two provide choice to be in the audit; nine state that routine screening consent covers audit. For two of the five that have an open disclosure policy for medical incidents, this policy applies to screening interval cancers. One other country/region has an open disclosure policy for category 3 interval cancers only. Five have legal protection for interval cancers arising in the screened population.

CONCLUSION

While consistency in providing aggregate programmatic audits exists, there is no consistent approach to individual interval cancer reviews or results disclosure.

Screen-detected ductal carcinoma in situ, 2008-2020: An observational study

OBJECTIVES

The purpose of this study was to evaluate the grade distribution of screen-detected ductal carcinoma in situ (DCIS) diagnosed in Ireland, in the context of the clinical trials currently underway to determine if active surveillance is a feasible management option for low-risk DCIS.

SETTING

BreastCheck is the national breast screening programme in Ireland, offering screening to women aged 50 to 69 every two years.

METHODS

This study was a secondary analysis of data collected by BreastCheck on all screen-detected DCIS diagnosed in the 12 years of nationwide screening. Incidence and detection rates were calculated. Descriptive analysis of the cases was performed and, for comparative analysis, grade of DCIS was analysed as a binary variable (high vs. low/intermediate) in keeping with the inclusion criteria for active surveillance trials. Analysis was performed in IBM Statistical Package for Social Sciences, version 26.

RESULTS

Between 2008 and 2020, 2240 women were diagnosed with DCIS through BreastCheck; 876 (39.1%) were low/intermediate-grade. The overall incidence rate has remained relatively stable during this period. Women with low/intermediate-grade DCIS were younger than women with high-grade DCIS (56 (interquartile range: 56-61) years v 57 (interquartile range: 53-61) years; p < 0.001). They were also more likely to have been diagnosed at an initial screening episode compared with those who had high-grade lesions (42.5% v 29.0%; p < 0.001).

CONCLUSION

If current clinical trials recommend active surveillance as a feasible option for DCIS, up to 40% of women with screen-detected DCIS may be eligible. These women are younger and often diagnosed on initial screening episode, so may require longer active follow-up.

Ductal Carcinoma in Situ in Ireland, 2008-2020: Screening Data related to Low-Risk Management Trials

Background

Four clinical trials are on-going to determine if active surveillance is a feasible management option for patients with low-risk ductal carcinoma in situ (DCIS), in response to concerns that breast cancer screening programmes have increased the incidence of DCIS, some of which may never progress to invasive cancer. This study aimed to describe the epidemiology of screen-detected DCIS in Ireland through the BreastCheck, the national breast screening programme in Ireland (commenced 2000 but fully national since 2008).

Methods

This was a cross-sectional analysis of anonymised BreastCheck data provided by the National Screening Service, including all cases of screen-detected DCIS between 2008 and 2020. Statistical tests included Mann-Whitney U, Chi square, and multivariable logistic regression.

Results

2,240 women were diagnosed with DCIS through BreastCheck between 2008 and 2020 (1353 (60.4%) high-grade and 876 (39.1%) low/intermediate grade). The overall rate of screen-detected DCIS incidence has remained relatively stable during this time. Women with high- grade DCIS were older than women with low/intermediate DCIS (57 (IQR 53-61) years v 56 (IQR 56-61) years; p &lt; 0.001). They were also more likely to have been diagnosed at a subsequent screening episode than at an initial episode (71.0% v 57.5%; p &lt; 0.001). After adjustment (deprivation score, screening unit and year) the odds ratio for high-grade was 1.62 (95% CI 1.30-2.03; p &lt; 0.001) for subsequent compared with initial screening episode.

Conclusions

When trial results are available, these data will assist with service planning should active surveillance be approved as a management option. Based on trial inclusion criteria, up to 40% of women diagnosed with DCIS through BreastCheck may be eligible for consideration for active surveillance. These women are younger and often diagnosed on initial screening episode, so may require longer active follow-up.

Key messages

Majority of DCIS in national screening programme is high grade. Randomised controlled trial evidence will provide guidance on management of low-risk DCIS.

Evolution of the National Breast Screening Programme in Ireland: Two-year interval analysis (2004–2013) of BreastCheck

Objective

Monitoring breast screening programmes is essential to ensure quality. BreastCheck, the national breast screening programme in the Republic of Ireland, commenced screening in 2000, with full national expansion in 2007, and digital mammography introduced in 2008. We aimed to review the performance of BreastCheck from 1 January 2004 to 31 December 2013.

Methods

Using the customised clinical and administrative database, performance indicator data were collected from BreastCheck and compared with programme and European guideline standards.

Results

Over the decade, 972,236 screening examinations were performed. Uptake initially rose following national expansion, but fell in the subsequent years to <70% in 2012–2013. Following the introduction of digital mammography, initial recall rates increased from 5.2% in 2004–2005 to 8.1% in 2012–2013. Subsequent recall rates remained within the target of <3%. On average, invasive cancer detection rates were 6.6/1000 for initial and 4.5/1000 for subsequent women. Small cancer detection rates were for <15 mm 43.4% (initial women) and 51.7% (subsequent) and for ≤10 mm 24.0% (initial) and 29.5% (subsequent). Ductal carcinoma in situ detection as a percentage of all cancers averaged 21.2% for initial and 20.0% for subsequent women. The majority were intermediate or high-grade ductal carcinoma in situ. The positive predictive value was 11.9% for initial and 21.8% for subsequent women. Standardized detection ratios remained above the programme target.

Conclusion

Revised indicators to reflect the digital mammography era are anticipated in revised European Guidelines on breast cancer screening.

Abstract P5-02-06: The impact of the introduction of breast cancer screening on a symptomatic breast cancer unit

This abstract was not presented at the symposium.

Comparison of the clinical performance of three digital mammography systems in a breast cancer screening programme

This study compares the clinical performance of three digital mammography system types in a breast cancer screening programme. 28 digital mammography systems from three different vendors were included in the study. The retrospective analysis included 238 182 screening examinations of females aged between 50 and 64 years over a 3-year period. All images were double read and assigned a result according to a 5-point rating scale to indicate the probability of cancer. Females with a positive result were recalled for further assessment imaging and biopsy if necessary. Clinical performance in terms of cancer detection rate was analysed and the results presented. No statistically significant difference was found between the three different mammography systems in a population-based screening programme, in terms of the overall cancer detection rate or in the detection of invasive cancer and ductal carcinoma in situ. This was shown in both prevalent and subsequent screening examination categories. The results demonstrate comparable cancer detection performance for the three imaging system types operational in the screening programme.

High malignancy yield in core needle biopsy of BIRADS 3 breast lesions with calcification

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Background: Breast cancer screening programmes reduce mortality but result in increased numbers of breast biopsies. Stereotactic and ultrasound-guided core needle biopsy yield similar results to each other and to open biopsy. Study: Analysis of prospectively-acquired data relating to 174,338 screening mammograms performed in BreastCheck between Jan 2001 to Oct 2004. Relative use of ultrasound and stereotactic guidance for core needle biopsy is ascertained, and malignancy yields analysed. Results: In this time period, 174,338 screening mammograms discovered a total of 2782 lesions requiring further assessment. Of 2760 complete records, 1066 were BiRads R3–5 (39%) and 1033 of these (97%) had CNB. Guidance was provided exclusively by ultrasound in 737 (71%), and by stereotaxis in 270 (26%) of cases. There were no differences in malignancy yield of ultrasound versus sterotactically-guided CNB of R4 and R5 lesions (approximately 50% and 90% respectively). The malignancy yield in R3 lesions was significantly higher when performed with stereotactic guidance (12%) than when performed with ultrasound-guidance (5%) and both were significantly higher than R3 biopsy malignancy yields reported in the literature. Conclusion: Almost all BIRADS 3, 4 and 5 lesions are biopsied. The relatively high malignancy yield in R3 biopsies, particularly those with calcification, supports current practice.

No significant financial relationships to disclose.