Population Breast Screening Research Articles

Impact of a risk based breast screening decision aid on understanding, acceptance and decision making

Internationally, population breast cancer screening is moving towards a risk-stratified approach and requires engagement and acceptance from current and future screening clients. A decision aid (www.defineau.org) was developed based on women’s views, values, and knowledge regarding risk-stratified breast cancer screening. This study aims to evaluate the impact of the decision aid on women’s knowledge, risk perception, acceptance of risk assessment and change of screening frequency, and decision-making. Here we report the results of a pre and post-survey in which women who are clients of BreastScreen Victoria were invited to complete an online questionnaire before and after viewing the decision aid. 3200 potential participants were invited, 242 responded with 127 participants completing both surveys. After reviewing the decision aid there was a significant change in knowledge, acceptance of risk-stratified breast cancer screening and of decreased frequency screening for lower risk. High levels of acceptance of risk stratification, genetic testing and broad support for tailored screening persisted pre and post review. The DEFINE decision aid has a positive impact on acceptance of lower frequency screening, a major barrier to the success of a risk-stratified program and may contribute to facilitating change to the population breast screening program in Australia.

Can population breast screening programs be leveraged to reduce the burden of breast cancer?

Breast cancer (BC) is the most common cancer in women. A study of the temporal trends (1998–2012) in the age-standardised incidence rate in 41 countries showed that increased BC incidence rates had occurred in pre- and post-menopausal women [[1]Heer E. Harper A. Escandor N. Sung H. McCormack V. Fidler-Benaoudia M.M. Global burden and trends in premenopausal and postmenopausal breast cancer: a population-based study.Lancet Global Health. 2020; 8: e1027-e1037Abstract Full Text Full Text PDF PubMed Scopus (207) Google Scholar]. However, increases exclusively in premenopausal ages were observed mainly in high-income countries, whereas the largest increases in the incidence of postmenopausal BC were observed predominantly in countries undergoing socioeconomic transitions. These findings probably reflect changes in the prevalence of various lifestyle factors that are known to increase BC risk, many of which are inherent in the social and economic circumstances of a population. Although many of these factors, such as reproductive history, alcohol, and (lack of) physical activity, are associated with BC risk across the lifespan, some, for example body fat/obesity and weight gain in adulthood, are associated with post-menopausal BC [[2]World Cancer Research Fund/American Institute for Cancer ResearchDiet, nutrition, physical activity and cancer: a global perspective. Continuous update project expert report 2018.2018Google Scholar]. Mammography screening reduces the risk of BC death through detection and treatment of early-stage disease. Population-based programs have been providing mammography screening to women aged ≥40 years for decades, but screening represents secondary prevention so cannot curb the growing incidence of BC. The interplay of BC risk factors throughout an individual's lifetime renders primary prevention difficult at a population level. Therefore, prevention efforts have focused on subgroups at substantially increased BC risk in whom effective strategies, such as risk-reducing surgery or chemoprevention, may be appropriate. Neither of these strategies can be recommended to the majority of women who are at average BC risk or thereabouts, who routinely present for screening. Contemplation of a new approach to screening, namely risk-stratified screening, has progressed to formal trialling and includes an element of prevention for those at increased BC risk [[3]Pashayan N. Antoniou A.C. Ivanus U. et al.Personalized early detection and prevention of breast cancer: ENVISION consensus statement.Nat Rev Clin Oncol. 2020; 17: 687-705Crossref PubMed Scopus (76) Google Scholar,[4]Esserman L.J. WISDOM Study and Athena InvestigatorsThe WISDOM Study: breaking the deadlock in the breast cancer screening debate.NPJ Breast Cancer. 2017; 3: 34Crossref PubMed Google Scholar]. While results from risk-stratified screening trials are awaited, BC screening programs could be leveraged from now to explore primary prevention in the broader female population participating at periodic intervals and starting screening at an age potentially amenable to lifestyle-related prevention. The development, evaluation, and uptake of lifestyle-related (prevention) interventions will prove to be challenging and would require additional investments to be integrated into existing screening programs, however this approach has the potential to be offered to all screening program participants. Most BC screening programs have data collection and follow-up processes to monitor outcomes which could be expanded to capture data on lifestyle-related risk factors (eg BMI). Program-embedded pilot studies could be established as a first step to investigate the feasibility of integrating primary prevention strategies alongside mammography screening and to assess specific interventions. Consensus on meaningful surrogate outcomes would be needed because changes in incidence, or mortality outcomes, require 10–20 years or longer to be observed. Essential to this proposed approach is funding and a broadly collaborative approach between population screening programs, BC stakeholders including consumers and researchers, and co-designed interventions to ensure acceptability to women and cultural appropriateness. None to declare. I receive research funding via the NBCF Chair in Breast Cancer Prevention (grant #EC-21-001).

Factors associated with attendance at screening for breast cancer: a systematic review and meta-analysis

ObjectiveAttendance at population-based breast cancer (mammographic) screening varies. This comprehensive systematic review and meta-analysis assesses all identified patient-level factors associated with routine population breast screening attendance.DesignCINAHL, Cochrane Library, Embase, Medline,...

Screening detects a myriad of breast disease - refining practice will increase effectiveness and reduce harm.

For many individuals, the term 'cancer' equates to a disease that if untreated will progress, spread from the area initially affected and ultimately cause death. 'Breast cancer', however, is a diverse of range of pathological entities, incorporating indolent to fast-growing and aggressive lesions, with varying histological patterns, clinical presentations, treatment responses and outcomes. Screening for malignancy is based on the assumption that cancer has a gradual, orderly progression and that detecting lesions earlier in their natural history, and intervening, will reduce mortality. The natural history of epithelial atypia, ductal carcinoma in situ and even invasive breast cancer is poorly understood, but widely variable. We believe that population breast screening methodology needs to change to focus on diagnosis of lesions of greatest clinical relevance.

Effect of population breast screening on breast cancer mortality to 2005 in England and Wales: A nested case-control study within a cohort of one million women.

Objectives To evaluate the effectiveness of the NHS breast screening programme (NHSBSP) on breast cancer mortality in England and Wales and to compare findings with a cohort analysis of the same underlying population. Methods A nested case-control study within a cohort of 959,738 women in England and Wales aged 49-64 who were eligible for routine NHSBSP screening during 1991-2005. Cases who died from breast cancer in 1991-2005 were matched to controls without breast cancer at the case diagnosis date and alive when the case died. Risk of breast cancer mortality associated with intention to screen (ITS) (7047 cases/28,188 controls) and screening attendance (4707 cases/9413 controls) was examined. Bias was minimised in accordance with currently advocated best practice. Odds ratios (ORs) were calculated using conditional logistic regression. Results were compared with findings from an incidence-based breast cancer mortality cohort analysis. Results ITS was associated with a 21% breast cancer mortality reduction (OR = 0.79, 95% confidence interval [CI]: 0.71-0.88, P < 0.001). Attendance ≤5 years before diagnosis was associated with a 47% reduction in breast cancer mortality after self-selection correction (OR = 0.53, 95% CI: 0.46-0.62, P < 0.001). Breast cancer mortality reduction associated with ITS was 21% in both the case-control and cohort analyses, but the impact of attendance was marginally greater in the case-control analysis (36% vs. 32%). Conclusions Case-control studies designed and analysed according to current best practice guidelines offer an effective means of evaluating population breast screening.

Comment on ‘Effect of population breast screening on breast cancer mortality up to 2005 in England and Wales: an individual-level cohort study’

Comment on ‘Effect of population breast screening on breast cancer mortality up to 2005 in England and Wales: an individual-level cohort study’

Overdiagnosis of breast cancer in population screening: does it make breast screening worthless?

The risk of breast cancer (BC) overdiagnosis attributed to mammography screening is an unresolved issue, complicated by heterogeneity in the methodology of quantifying its magnitude, and both political and scientific elements surrounding interpretation of the evidence on this phenomenon. Evidence from randomized trials and also from observational studies shows that mammography screening reduces the risk of BC death; similarly, these studies provide sufficient evidence that overdiagnosis represents a serious harm from population breast screening. For both these outcomes of screening, BC mortality reduction and overdiagnosis, estimates of magnitude vary between studies however overdiagnosis estimates are associated with substantial uncertainty. The trade-off between the benefit and the collective harms of BC screening, including false-positives and overdiagnosis, is more finely balanced than initially recognized, however the snapshot of evidence presented on overdiagnosis does not mean that breast screening is worthless. Future efforts should be directed towards (a) ensuring that any changes in the implementation of BC screening optimize the balance between benefit and harms, including assessing how planned or actual changes modify the risk of overdiagnosis; (b) informing women of all the outcomes that may affect them when they participate in screening using well-crafted and balanced information; and (c) investing in research that will help define and reduce the ensuing overtreatment of screen-detected BC.

Effect of population breast screening on breast cancer mortality up to 2005 in England and Wales: an individual-level cohort study

Background:Population breast screening has been implemented in the UK for over 25 years, but the size of benefit attributable to such programmes remains controversial. We have conducted the first individual-based cohort evaluation of population breast screening in the UK, to estimate the impact of the NHS breast screening programme (NHSBSP) on breast cancer mortality.Methods:We followed 988 090 women aged 49–64 years in 1991 resident in England and Wales, who because of the staggered implementation of the NHSBSP, included both invited subjects and an uninvited control group. Individual-level breast screening histories were linked to individual-level mortality and breast cancer incidence data from national registers. Risk of death from breast cancer was investigated by incidence-based mortality analyses in relation to intention to screen and first round attendance. Overdiagnosis of breast cancer following a single screening round was also investigated.Results:Invitation to NHSBSP screening was associated with a reduction in breast cancer mortality in 1991–2005 of 21% (RR=0.79, 95% CI: 0.73–0.84, P<0·001) after adjustment for age, socioeconomic status and lead-time. Breast cancer deaths among first invitation attenders were 46% lower than among non-attenders (RR=0.54, 95% CI: 0.51–0·57, P<0.001) and 32% lower following adjustment for age, socioeconomic status and self-selection bias (RR=0.68, 95% CI: 0.63–0·73, P<0.001). There was little evidence of overdiagnosis associated with invitation to first screen.Conclusions:The results indicate a substantial, statistically significant reduction in breast cancer mortality between 1991 and 2005 associated with NHSBSP activity. This is important in public health terms.

A comparison of two digital mammography systems: are there any differences?

To compare the performance of two newly introduced digital mammography technologies (Sectra and Hologic) to the Welsh breast-screening service; specifically, whether there are differences in the number, type, size, and grade of tumour identified. This was a retrospective study of a prospectively collected database of 50,000 consecutive screening episodes from 2012; clients were aged 49-88 years (mean 61.9 years). All studies were double-blind read by two readers. All tumours identified in the two arms of the study were detailed and compared specifically with regards to type (ductal or lobular) size, grade, and whether invasive or non-invasive. Performance was analysed for any statistically significant differences. Twenty-five thousand consecutive women were screened with Hologic (recall rate 5.9% of which 18% were cancer) and 25,000 were screened with Sectra digital mammography (recall rate 4.3% and 22% were cancer). Five hundred tumours were found with no significant difference in invasive cancer detection or between ductal or lobular subtypes. The Hologic system detected 267 tumours; of which 81 (30.33%) were non-invasive (3.24 per 1000), compared to the Sectra system with 233 cancers overall including 36 non-invasive (15.45%, 1.44 per 1000). The difference in non-invasive lesions (mainly ductal carcinoma in situ [DCIS]) detection was significant (p<0.001); 38% of which were high nuclear grade (HNG) using Hologic and 50% HNG lesions using Sectra. There was no significant difference in non-invasive size between the two technologies. The mean glandular dose received using the Sectra system was significantly less (0.7mGy) compared to the Hologic system (1.6mGy) for a 50-60mm breast thickness. Population breast screening is frequently criticised for identifying lesions irrelevant to long-term outcomes or life expectancy and although the two systems seem comparable in terms of invasive cancer detection, a statistically significant difference in the detection of non-invasive lesions was seen, not reported in previous studies. This is a contentious issue, as identifying more DCIS has the potential to over-diagnose screened women leading to increased morbidity, higher "cancer detection rates", longer cancer waiting times, and reduced patient psychological wellbeing. The Sectra system is able to deliver a similar invasive detection cancer delivering a much lower dose mammogram, which is important in limiting overall population radiation dose. Further study as to whether the differences in tumour detection rates are clinically significant long term are now required.

Effect of integrating 3D-mammography (digital breast tomosynthesis) with 2D-mammography on radiologists’ true-positive and false-positive detection in a population breast screening trial

ObjectiveWe investigated the effect of integrating three-dimensional (3D)-mammography with 2D-mammography on radiologists’ detection measures in the ‘screening with tomosynthesis or standard mammography’ (STORM) trial. MethodsSTORM, a prospective population-based trial (Trento and Verona breast screening services) compared sequential screen-reading: 2D-mammography alone and integrated 2D/3D-mammography. Radiologist-specific detection measures were calculated for each screen-reading phase for eight radiologists: number of detected cancers, proportion of true-positive (TP) detection, and number and rate of false-positive (FP) recalls (FPR). We estimated the incremental cancer detection rate (CDR). ResultsThere were 59 cancers and 395 false recalls amongst 7292 screening participants. At 2D-mammography screening, radiologist-specific TP detection ranged between 38% and 83% (median 63%; mean 60% and sd 15.4%); at integrated 2D/3D-mammography, TP detection ranged between 78% and 93% (median 87%; mean 87% and sd 5.2%). For all but one radiologist, 2D/3D-mammography improved breast cancer detection (relative to 2D-mammography) ranging between 0% and 54% (median 29%; mean 27% and sd 16.2%) increase in the proportion of detected cancers. Incremental CDR attributable to integrating 3D-mammography in screening varied between 0/1000 and 5.3/1000 screens (median 1.8/1000; mean 2.3/1000 and sd 1.6/1000). Radiologist-specific FPR for 2D-mammography ranged between 1.5% and 4.2% (median 3.1%; mean 2.9% and sd 0.87%), and FPR based on the integrated 2D/3D-mammography read ranged between 1.0% and 3.3% (median 2.4%; mean 2.2% and sd 0.72%). Integrated 2D/3D-mammography screening, relative to 2D-mammography, had the effect of reducing FP and increasing TP detection for most radiologists. ConclusionThere was broad variability in radiologist-specific TP detection at 2D-mammography and hence in the additional TP detection and incremental CDR attributable to integrated 2D/3D-mammography; more consistent (less variable) TP-detection estimates were observed for the integrated screen-read. Integrating 3D-mammography with 2D-mammography improves radiologists’ screen-reading through improved cancer detection and/or reduced FPR, with most readers achieving both using integrated 2D/3D mammography.

Radiographer gender in a population breast screening programme -would it matter?

Radiographer gender in a population breast screening programme -would it matter?

Two-view mammography: the Welsh experience and overview

In Wales, population breast screening using mammography, within the National Health Service Breast Screening Programme (NHSBSP), commenced in February 1989. It was gradually rolled out across the Principality over the next 3 years by Breast Test Wales with the prevalent screening round completing in 1995. From its inception, two-view mammography was the standard for all prevalent round screens in Wales, unlike many other screening programmes that relied on a single view. This resulted in higher than expected cancer detection rates as compared with the Swedish Two County trial and other NHSBSP results. In Wales 9.2 breast cancers per 1000 women screened were found compared with an average of 6.3 per 1000 in the rest of the UK in the prevalent round. For incident round screens, it was decided that single-view mammography was appropriate. The results were less impressive, with cancer detection dropping to standardised detection ratio values of less than one. There may be several reasons for this anomaly, not least of which is the possibility that more subtle cancers, including those only visible on the cranio-caudal view, had been identified at the prevalent screen and were thus not present to be picked up at subsequent incident rounds. In 2000, when the National Assembly for Wales made monies available to extend screening up to the age of 70 years, it was decided that, firstly, the programme should revert to two-view screening, but this time for all rounds. The results of these first two-view incident round figures will be presented. There has been an increase in cancer detection of around 39%, similar to that predicted by Blanks and Moss in their studies. The first 18 months of two-view incident round screening increased the cancer detection rate in these women from 5.38 to 7.5 per 1000 screened. This included an increase in the small cancers detected from 2.30 to 3.30 per 1000. The recall to assessment figures also rose, surprisingly from 3.8% to 4.5%, although the rise has not been sustained more recently. In some areas the first incident two-view round has been completed; data on this will be presented. It is, however, unlikely that this increase in cancer detection will persist in subsequent incident rounds and a steady state will be reached, but at a higher level of cancer detection than with single-view incident screening. It is hoped that, in contrast, the interval cancer rate will drop accordingly. Early data on interval cancers will also be presented.

Ductal carcinoma in situ (DCIS): are we overtreating it?

DCIS continues to increase in incidence as the number of women invited to population breast screening programmes increases. This means that more women are treated every year for DCIS. More women diagnosed with DCIS currently receive some form of treatment and the issue is whether this treatment is necessary and appropriate. There are few data on the natural history of untreated DCIS. Studies from Nashville by Page [1] show 28% of patients with low grade DCIS develop invasive disease by 6 years and 40% have developed invasive disease by 30 years. Data from Van Nuys [2] suggest that the rate of progression in high grade DCIS is much higher, with 60% of women with incompletely excised high grade disease developing progression or invasive cancer by 5 years. The results of studies on treatment of DCIS can be summarised as follows: • Excision alone is associated with a high rate of local recurrence in approximately 3.8% per year, of which 1.6% per year is invasive disease. • Radiotherapy reduces the recurrence rate in the progression to invasive cancer by between 50 and 60%. • Recurrence rates are lower when radiotherapy is given to patients whose lesion is completely excised with clear margins. The evidence that wider margins is associated with better local control rates does not stand up to scrutiny. Surgeons in the UK are divided as to what they consider to be an adequate clear margin width. • Tamoxifen reduces recurrence rates in oestrogen receptor-positive DCIS but not oestrogen receptor-negative DCIS. • No patients with localised DCIS should have axillary surgery. As the numbers of patients with DCIS increases, so the number of women being treated by breast-conserving surgery and mastectomy increases. The challenge is to limit the surgery so as to reduce morbidity and select those patients who will have most to gain from radiotherapy and tamoxifen.

Computer-assisted mammographic imaging.

Computer-assisted mammography imaging comprises computer-based analysis of digitized images resulting in prompts aiding mammographic interpretation and computerized stereotactic localization devices which improve location accuracy. The commercial prompting systems available are designed to draw attention to mammographic abnormalities detected by algorithms based on symptomatic practise in North America. High sensitivity rates are important commercially but result in increased false prompt rates, which are known to distract radiologists. A national shortage of breast radiologists in the UK necessitates evaluation of such systems in a population breast screening programme to determine effectiveness in increasing cancer detection and feasibility of implementation.