Comparison of interval breast cancer rates for two-versus single-view screening mammography: a population-based study

Considerations for Evaluating the Introduction of New Cancer Screening Technology: Use of Interval Cancers to Assess Potential Benefits and Harms

This framework focuses on the importance of the consideration of the downstream intermediate and long-term health outcomes when a change to a screening program is introduced. The authors present a methodology for utilising the relationship between screen-detected and interval cancer rates to infer the benefits and harms associated with a change to the program. A review of the previous use of these measures in the literature is presented. The framework presents other aspects to consider when utilizing this methodology, and builds upon an existing framework that helps researchers, clinicians, and policy makers to consider the impacts of changes to screening programs on health outcomes. It is hoped that this research will inform future evaluative studies to assess the benefits and harms of changes to screening programs.

Association between Screening Mammography Recall Rate and Interval Cancers in the UK Breast Cancer Service Screening Program: A Cohort Study

Purpose To determine whether low levels of recall lead to increased interval cancers and the magnitude of this effect. Materials and Methods The authors retrospectively analyzed prospectively collected data from the UK National Health Service Breast Screening Programme during a 36-month period (April 1, 2005 to March 31, 2008), with 3-year follow-up in women aged 50-70 years. Data on recall, cancers detected at screening, and interval cancers were available for each of the 84 breast screening units and for each year (n = 252). The association between interval cancers and recalls was modeled by using Poisson regression on aggregated data and according to age (5-year intervals) and screening type (prevalent vs incident). Results The authors analyzed 5 126 689 screening episodes, demonstrating an average recall to assessment rate (RAR) of 4.56% (range, 1.64%-8.42%; standard deviation, 1.15%), cancer detection rate of 8.1 per 1000 women screened, and interval cancer rate (ICR) of 3.1 per 1000 women screened. Overall, a significant negative association was found between RAR and ICR (Poisson regression coefficient: -0.039 [95% confidence interval: -0.062, -0.017]; P = .001), with approximately one fewer interval cancer for every additional 80-84 recalls. Subgroup analysis revealed similar negative correlations in women aged 50-54 years (P = .002), 60-64 years (P = .01), and 65-69 years (P = .008) as well as in incident screens (P = .001) and prevalent screens (P = .04). No significant relationship was found in women aged 55-59 years (P = .46). Conclusion There was a statistically significant negative correlation between RAR and ICR, which suggests the merit of a minimum threshold for RAR. © RSNA, 2018 Online supplemental material is available for this article.

The epidemiology, radiology and biological characteristics of interval breast cancers in population mammography screening

An interval breast cancer is a cancer that emerges following a negative mammographic screen. This overview describes the epidemiology, and the radiological and biological characteristics of interval breast cancers in population mammography screening. Notwithstanding possible differences in ascertainment of interval breast cancers, there was broad variability in reported interval breast cancer rates (range 7.0 to 49.3 per 10,000 screens) reflecting heterogeneity in underlying breast cancer rates, screening rounds (initial or repeat screens), and the length and phase of the inter-screening interval. The majority of studies (based on biennial screening) reported interval breast cancer rates in the range of 8.4 to 21.1 per 10,000 screens spanning the two-year interval with the larger proportion occurring in the second year. Despite methodological limitations inherent in radiological surveillance (retrospective mammographic review) of interval breast cancers, this form of surveillance consistently reveals that the majority of interval cancers represent either true interval or occult cancers that were not visible on the index mammographic screen; approximately 20–25% of interval breast cancers are classified as having been missed (false-negatives). The biological characteristics of interval breast cancers show that they have relatively worse tumour prognostic characteristics and biomarker profile, and also survival outcomes, than screen-detected breast cancers; however, they have similar characteristics and prognosis as breast cancers occurring in non-screened women. There was limited evidence on the effect on interval breast cancer frequency and outcomes following transition from film to digital mammography screening.

Interval cancer rates in the Irish national breast screening programme

OBJECTIVE

To compare interval cancer rates from the Irish breast screening programme, BreastCheck, for the period 2000-2007 with those from other European countries.

METHODS

Data from BreastCheck was linked to National Cancer Registry breast cancer registrations, to calculate numbers of women screened, screen-detected cancers, and interval cancers, by year of screening, in the first and second years after screening, and by initial or subsequent screen. Estimated underlying cancer incidence from the period 1996-1999 inclusive was used to calculate proportionate incidence. We calculated the interval cancer ratio as an alternative measure of the burden of interval cancers.

RESULTS

There were 372,658 screening records for 178,147 women in the period 2000-2007. The overall interval rate was 9.6 per 10,000 screens. In the first year after screening, the interval cancer rate was 5.8 per 10,000 screens and this increased to 13.4 in the second year after screening. The screen detection rate for the period was 53.6 per 10,000 screened for all screens combined. Initial screens produced a higher detection rate at 66.9 per 10,000 screened compared with subsequent screens with a screen-detected rate of 41.4 per 10,000 screens.

CONCLUSION

Interval breast cancer rates for the first years of the programme are within acceptable limits and are comparable with those in other European programmes. Nationwide roll-out together with the adoption of digital mammography may have an impact on interval cancer rates in future years.

Impact of risk factors on different interval cancer subtypes in a population-based breast cancer screening programme

Background

Interval cancers are primary breast cancers diagnosed in women after a negative screening test and before the next screening invitation. Our aim was to evaluate risk factors for interval cancer and their subtypes and to compare the risk factors identified with those associated with incident screen-detected cancers.

Methods

We analyzed data from 645,764 women participating in the Spanish breast cancer screening program from 2000–2006 and followed-up until 2009. A total of 5,309 screen-detected and 1,653 interval cancers were diagnosed. Among the latter, 1,012 could be classified on the basis of findings in screening and diagnostic mammograms, consisting of 489 true interval cancers (48.2%), 235 false-negatives (23.2%), 172 minimal-signs (17.2%) and 114 occult tumors (11.3%). Information on the screening protocol and women's characteristics were obtained from the screening program registry. Cause-specific Cox regression models were used to estimate the hazard ratios (HR) of risks factors for interval cancer and incident screen-detected cancer. A multinomial regression model, using screen-detected tumors as a reference group, was used to assess the effect of breast density and other factors on the occurrence of interval cancer subtypes.

Results

A previous false-positive was the main risk factor for interval cancer (HR = 2.71, 95%CI: 2.28–3.23); this risk was higher for false-negatives (HR = 8.79, 95%CI: 6.24–12.40) than for true interval cancer (HR = 2.26, 95%CI: 1.59–3.21). A family history of breast cancer was associated with true intervals (HR = 2.11, 95%CI: 1.60–2.78), previous benign biopsy with a false-negatives (HR = 1.83, 95%CI: 1.23–2.71). High breast density was mainly associated with occult tumors (RRR = 4.92, 95%CI: 2.58–9.38), followed by true intervals (RRR = 1.67, 95%CI: 1.18–2.36) and false-negatives (RRR = 1.58, 95%CI: 1.00–2.49).

Conclusion

The role of women's characteristics differs among interval cancer subtypes. This information could be useful to improve effectiveness of breast cancer screening programmes and to better classify subgroups of women with different risks of developing cancer.

Women's participation in breast cancer screening in France--an ethical approach

Background

Breast cancer is a major public health challenge. Organized mammography screening (OS) is considered one way to reduce breast cancer mortality. EU recommendations prone mass deployment of OS, and back in 2004, France introduced a national OS programme for women aged 50–74 years. However, in 2012, participation rate was still just 52.7%, well short of the targeted 70% objective. In an effort to re-address the (in) efficiency of the programme, the French National Cancer Institute has drafted an expert-group review of the ethical issues surrounding breast cancer mammography screening.

Discussion

Prompted by emerging debate over the efficiency of the screening scheme and its allied public information provision, we keynote the experts’ report based on analysis of epidemiological data and participation rate from the public health authorities. The low coverage of the OS scheme may be partly explained by the fact that a significant number of women undergo mammography outside OS and thus outside OS criteria. These findings call for further thinking on (i) the ethical principles of beneficence and non-malfeasance underpinning this public health initiative, (ii) the reasons behind women’s and professionals’ behavior, and (iii) the need to analyze how information provision to women and the doctor-patient relationship need to evolve in response to scientific controversy over the risks and benefits of conducting mammographic screening.

Summary

This work calls for a reappraisal of the provision of screening programme information. We advocate a move to integrate the points sparking debate over the efficiency of the screening scheme to guarantee full transparency. The perspective is to strengthen the respect for autonomy allowing women to make an informed choice in their decision on whether or not to participate.

Reduction in interval cancer rates following the introduction of two-view mammography in the UK breast screening programme

BACKGROUND

The introduction of two-view mammography at incident (subsequent) screens in the National Health Service Breast Screening Programme (NHSBSP) has led to an increased number of cancers detected at screen. However, the effect of two-view mammography on interval cancer rates has yet to be assessed.

METHODS

Routine screening and interval cancer data were collated from all screening programmes in the United Kingdom for women aged 50-64, screened between 1 April 2003 and 31 March 2005. Interval cancer rates were compared based on whether two-view mammography was in use at the last routine screen.

RESULTS

The reduction in interval cancers following screening using two-view mammography compared with one view was 0.68 per 1,000 women screened. Overall, this suggests the introduction of two-view mammography at incident screen was accompanied by a 15-20% reduction in interval cancer rates in the NHSBSP.

CONCLUSION

The introduction of two-view mammography at incident screens is associated with a reduction in incidence of interval cancers. This is consistent with previous publications on a contemporaneous increase in screen-detected cancers. The results provide further evidence of the benefit of the use of two-view mammography at incident screens.

[Classification and characteristics of interval cancers in the Principality of Asturias's Breast Cancer Screening Program]

OBJECTIVE

To review and classify the interval cancers found in the Principality of Asturias's Breast Cancer Screening Program (PDPCM). A secondary objective was to determine the histological characteristics, size, and stage of the interval cancers at the time of diagnosis.

MATERIAL AND METHODS

We included the interval cancers in the PDPCM in the period 2003-2007. Interval cancers were classified according to the breast cancer screening program protocol, with double reading without consensus, without blinding, with arbitration. Mammograms were interpreted by 10 radiologists in the PDPCM.

RESULTS

A total of 33.7% of the interval cancers could not be classified; of the interval cancers that could be classified, 40.67% were labeled true interval cancers, 31.4% were labeled false negatives on screening, 23.7% had minimal signs, and 4.23% were considered occult. A total of 70% of the interval cancers were diagnosed in the year of the period between screening examinations and 71.7% were diagnosed after subsequent screening. A total of 76.9% were invasive ductal carcinomas, 61.1% were stage II when detected, and 78.7% were larger than 10mm when detected.

CONCLUSIONS

The rate of interval cancers and the rate of false negatives in the PDPCM are higher than those recommended in the European guidelines. Interval cancers are diagnosed later than the tumors detected at screening. Studying interval cancers provides significant training for the radiologists in the PDPCM.

Overdiagnosis from non-progressive cancer detected by screening mammography: stochastic simulation study with calibration to population based registry data

OBJECTIVE

To quantify the magnitude of overdiagnosis from non-progressive disease detected by screening mammography, after adjustment for the potential for lead time bias, secular trend in the underlying risk of breast cancer, and opportunistic screening.

DESIGN

Approximate bayesian computation analysis with a stochastic simulation model designed to replicate standardised incidence rates of breast cancer. The model components included the lifetime probability of breast cancer, the natural course of breast cancer, and participation in organised and opportunistic mammography screening.

SETTING

Isère, a French administrative region with nearly 1.2 million inhabitants.

PARTICIPANTS

All women living in Isère and aged 50-69 during 1991-2006.

MAIN OUTCOME MEASURES

Overdiagnosis, defined as the proportion of non-progressive cancers among all cases of invasive cancer and carcinoma in situ detected 1991-2006.

RESULTS

In 1991-2006, overdiagnosis from non-progressive disease accounted for 1.5% of all cases of invasive cancer (95% credibility interval 0.3% to 2.9%) and 28.0% of all cases of carcinoma in situ (2.2% to 59.8%) detected either clinically or by screening mammography in Isère. When analysis was restricted to the cancers detected by screening mammography only, the estimates of overdiagnosis were 3.3% (0.7% to 6.5%) and 31.9% (2.9% to 62.3%) for invasive cancer and carcinomas in situ, respectively.

CONCLUSION

Overdiagnosis from the detection of non-progressive disease by screening mammography was limited in 1991-2006 in Isère. Because carcinoma in situ accounted for less than 15% of all incident breast cancer cases, its contribution to overdiagnosis was relatively limited and imprecise.