A remarkable reduction of breast cancer deaths in screened versus unscreened women: a case-referent study

Breast cancer outcomes based on method of detection in community-based breast cancer registry

PURPOSE

The impact of opportunistic screening mammography in the United States is difficult to quantify, partially due to lack of inclusion regarding method of detection (MOD) in national registries. This study sought to determine the feasibility of MOD collection in a multicenter community registry and to compare outcomes and characteristics of breast cancer based on MOD.

METHODS

We conducted a retrospective study of breast cancer patients from a multicenter tumor registry in Missouri from January 2004 - December 2018. Registry data were extracted by certified tumor registrars and included MOD, clinicopathologic information, and treatment. MOD was assigned as screen-detected or clinically detected. Data were analyzed at the patient level. Chi-squared tests were used for categorical variable comparison and Mann-Whitney-U test was used for numerical variable comparison.

RESULTS

5351 women (median age, 63 years; interquartile range, 53-73 years) were included. Screen-detected cancers were smaller than clinically detected cancers (median size 12 mm vs. 25 mm; P < .001) and more likely node-negative (81% vs. 54%; P < .001), lower grade (P < .001), and lower stage (P < .001). Screen-detected cancers were more likely treated with lumpectomy vs. mastectomy (73% vs. 41%; P < .001) and less likely to require chemotherapy (24% vs. 52%; P < .001). Overall survival for patients with invasive breast cancer was higher for screen-detected cancers (89% vs. 74%, P < .0001).

CONCLUSION

MOD can be routinely collected and linked to breast cancer outcomes through tumor registries, with demonstration of significant differences in outcome and characteristics of breast cancers based on MOD. Routine inclusion of MOD in US tumor registries would help quantify the impact of opportunistic screening mammography in the US.

Cone-beam breast CT-guided surface location facilitates breast-conserving surgery in breast cancer patients with extensive calcifications: A pilot study

Background

Extensive malignant-appearing calcifications have traditionally been considered a contraindication for breast-conserving surgery. The evaluation of calcifications largely depends on mammography, which is limited by tissue superimposition and is unable to reveal spatial information about extensive calcifications. Three-dimensional imaging modality is needed to reveal the architecture of extensive calcifications. In the present study, a novel cone-beam breast CT-guided surface location technique was investigated to facilitate breast-conserving surgery in breast cancer patients with extensive malignant breast calcifications.

Methods

Biopsy-proved early breast cancer patients with extensive malignant-appearing breast calcifications were included. A patient will be considered suitable for breast-conserving surgery if the spatial segmental distribution of calcifications is found by 3D images of cone-beam breast CT. Then, the margins of the calcifications were located in contrast-enhanced cone-beam breast CT images. Next, skin markers were located using radiopaque materials, and cone-beam breast CT was reperformed to confirm the accuracy of surface location. During breast-conserving surgery, lumpectomy was performed according to the previous surface location, and an intraoperative specimen x-ray was applied to double-check that the entire lesion was removed. Margin assessment was made for both intraoperative frozen section and postoperative pathology examination.

Results

From May 2019 to Jun 2022, 11 eligible breast cancer patients in our institution were included. Breast-conserving surgery was performed successfully in all patients using the surface location approach mentioned before. All patients achieved negative margins and satisfied cosmetic results.

Conclusion

This study proved the feasibility of cone-beam breast CT-guided surface location for facilitating breast-conserving surgery in breast cancer patients with extensive malignant breast calcifications.

The effect of the Flemish breast cancer screening program on breast cancer-specific mortality: A case-referent study

BACKGROUND

Breast cancer screening programs were introduced in many countries worldwide following randomized controlled trials in the 1980s showing a reduction in breast cancer-specific mortality. However, their effectiveness remains debated and estimates vary. A breast cancer screening program was introduced in 2001 in Flanders, Belgium where high levels of opportunistic screening practices are observed. The effectiveness of this program was estimated by measuring its effect on breast cancer-specific mortality.

METHODS

We performed a case-referent study to investigate the effect of participation in the Flemish population-based mammography screening program (PMSP) on breast cancer-specific mortality from 2005 to 2017. A multiple logistic regression model assessed the association between breast cancer-specific death and screening program participation status in the four years prior to (pseudo)diagnosis (yes/no), with adjustment for potential confounders (individual socio-economic position and calendar year of diagnosis) and stratified for age. In addition, we performed different sensitivity analyses.

RESULTS

We identified 1571 cases and randomly selected 6284 referents. After adjustment, women who participated in PMSP had a 51 % lower risk of breast cancer-specific mortality compared to those who did not (adjusted odds ratio [aOR] =0.49, 95 % CI: 0.44-0.55). Sensitivity analyses did not markedly change the estimated associations. Correction for self-selection bias reduced the effect size, but the estimate remained significant.

CONCLUSION

Our results indicate that in a context of high opportunistic screening rates, participation in breast cancer screening program substantially reduces breast cancer-specific mortality. For policy, these results should be balanced against the potential harms of screening, including overdiagnosis and overtreatment.

Misinformation and Facts about Breast Cancer Screening

Quality medical practice is based on science and evidence. For over a half-century, the efficacy of breast cancer screening has been challenged, particularly for women aged 40-49. As each false claim has been raised, it has been addressed and refuted based on science and evidence. Nevertheless, misinformation continues to be promoted, resulting in confusion for women and their physicians. Early detection has been proven to save lives for women aged 40-74 in randomized controlled trials of mammography screening. Observational studies, failure analyses, and incidence of death studies have provided evidence that there is a major benefit when screening is introduced to the general population. In large part due to screening, there has been an over 40% decline in deaths from breast cancer since 1990. Nevertheless, misinformation about screening continues to be promoted, adding to the confusion. Despite claims to the contrary, a careful reading of the guidelines issued by major groups such as the U.S. Preventive Services Task Force and the American College of Physicians shows that they all agree that most lives are saved by screening starting at the age of 40. There is no scientific support for using the age of 50 as a threshold for screening. All women should be provided with the facts and not false information about breast cancer screening so that they can make "informed decisions" for themselves about whether to participate.

Design, implementation, and pitfalls of TMIST

The early detection of breast cancer has been shown to reduce deaths through randomized, controlled trials. Numerous observational studies, failure analyses, and "incidence of death" studies have confirmed that screening reduces deaths in the general population. Digital Breast Tomosynthesis (DBT) which collects mammographic images from different angles and uses them to synthesize planes through the breast is simply another advance in mammography among others that have been made over the years. DBT "absolutely" detects more cancers at a time when cure is more likely while also having the advantage of reducing recall rates. The Tomosynthesis Mammographic Imaging Screening Trial (TMIST) has been designed to compare DBT with 2-Dimensional Full Field Digital Mammography (FFDM), but it's major design issues may provide misleading results. Instead of using a reduction in deaths as the endpoint, benefit in TMIST is predicated on a reduction in advanced cancers in the DBT group. This is a questionable "endpoint" (a reduction in advanced cancers is not necessary as proof of benefit). In addition, the trial may be underpowered so that even if DBT shows a benefit it may not be able to achieve "statistical significance". The six CISNET models of the National Cancer Institute have shown that annual mammography beginning at the age of 40 will save the most lives. Yet TMIST will only include women ages 45 and over and will screen postmenopausal women every two years instead of annually. Consequently, TMIST results may be used, inappropriately, to limit access to breast cancer screening starting at the age of 45, and only offer biennial screening for post-menopausal women.

The wisdom trial is based on faulty reasoning and has major design and execution problems

PURPOSE

To evaluate the design and plan of execution of the "WISDOM" trial.

METHODS

The rationale and reasoning behind the WISDOM Trial were reviewed and analyzed. The published parameters of the trial were reviewed.

RESULTS

The study is based on a failed understanding of the available data about breast cancer screening and is based on faulty assumptions, false reasoning, a scientifically unsupportable study design, ignoring advances in screening, a questionable endpoint, the likely lacking of power to answer the primary question, and support by insurance companies whose primary goal is almost certainly to reduce their costs.

CONCLUSION

A major part of the premise is that there is a "debate" about the efficacy of screening. WISDOM ignores the fact that the "debate" has been manufactured and is not science-based. The results of the WISDOM Trial may be misleading.

Comparison of Call-Back Rates between Digital Mammography and Digital Breast Tomosynthesis

The effect of mammographic screening on the natural history and evolution of breast cancer treatment cannot be overstated; however, despite intensive and resource consuming screening, advanced breast cancer is still diagnosed frequently. The development of three-dimensional mammography or digital breast tomosynthesis (DBT) has already demonstrated greater sensitivity in the diagnosis of breast pathology and effectiveness in identifying early breast cancers. In addition to being a more sensitive screening tool, other studies indicate DBT has a lower call-back rate when compared with traditional DM. This study compares call-back rates between these two screening tools. A single institution, retrospective review was conducted of almost 20,000 patient records who underwent digital mammography or DBTin the years 2016 to 2018. These charts were analyzed for documentation of imaging type, Breast Imaging Reporting and Data System 0 status, call-back status, and type of further imaging that was required. Charts for 19,863 patients were reviewed, 17,899 digital mammography examinations were conducted compared with 11,331 DBT examinations resulting in 1,066 and 689 Breast Imaging Reporting and Data System 0 studies, respectively. Of the DM call-backs, 82.08 per cent were recommended for additional radiographic imaging and 17.82 per cent for ultrasound imaging. In the DBT group, only 39.77 per cent of callbacks were recommended for additional radiographic imaging and 60.09 per cent for ultrasound imaging. Our data suggest that DBT results in less call-back for additional mammographic images as compared with digital mammography. DBT may offer benefits over DM, including less imaging before biopsy, less time before biopsy, quicker diagnosis, and improved patient satisfaction.

Dedicated Breast Computed Tomography With a Photon-Counting Detector: Initial Results of Clinical In Vivo Imaging

OBJECTIVES

The purpose of this work is to present the data obtained from the first clinical in vivo application of a new dedicated spiral breast computed tomography (B-CT) equipped with a photon-counting detector.

MATERIALS AND METHODS

The institutional review board approved this retrospective study. Twelve women referred for breast cancer screening were included and underwent bilateral spiral B-CT acquired in prone position. Additional sonography was performed in case of dense breast tissue or any B-CT findings. In 3 women, previous mammography was available for comparison. Soft tissue (ST) and high-resolution (HR) images were reconstructed. Two independent radiologists performed separately the readout for subjective image quality and for imaging findings detection. Objective image quality evaluation was performed in consensus and included spatial resolution, contrast resolution, signal-to-noise ratio (SNR), and contrast-to-noise ratio. All women were asked to report about positioning comfort and overall comfort during data acquisition.

RESULTS

The major pectoral muscle was included in 15 breast CT scans (62.5%); glandular component was partially missing in 2 (8.3%) of the 24 scanned breasts. A thin "ring artifact" was present in all scans but had no influence on image interpretations; no other artifacts were present. Subjective image quality assessment showed excellent agreement between the 2 readers (κ = 1). Three masses were depicted in B-CT and were confirmed as simple cysts in sonography. Additional 5 simple cysts and 2 solid benign lesions were identified only in sonography. A total of 12 calcifications were depicted with a median size of 1.1 mm (interquartile range, 0.7-1.7 mm) on HR and 1.4 mm (interquartile range, 1.1-1.8 mm) on ST images. Median SNRgl, SNRfat, and contrast-to-noise ratio were significantly higher in ST than in HR reconstructions (each, P < 0.001). A mild discomfort due to positioning of the rib cage on the table was reported by 2 women (16.7%); otherwise, no discomfort was reported.

CONCLUSIONS

The new dedicated B-CT equipped with a photon-counting detector provides high-quality images with potential for screening of breast cancer along with minor patient discomfort.

Antecedents: A Half-Century of Imaging the Breast

The field of Breast Imaging evolved because a fairly small number of dedicated individuals realized the lifesaving potential of detecting breast cancer earlier. They persevered despite persistent efforts to curtail screening. From the first attempts to produce X-ray images of the breast to magnetic resonance and digital breast tomosynthesis, investigators have worked continuously to develop better ways to detect breast cancer at a time when cure is possible, while working continuously to preserve access for women to screening. Consequently, the death rate from breast cancer has declined by more than 40%. Therapy has improved, but therapy saves lives when breast cancers are treated early.

The breast surgeons' approach to mastectomy and prepectoral breast reconstruction

The purpose of this review article is to discuss and highlight the data, techniques and our experience performing mastectomies in the setting of prepectoral breast reconstruction. Using a systematic review of the approach to mastectomy in the oncologic setting encompassing patient selection, safety, anatomy and methods including a literature review of mastectomy trends, safety data and outcomes, anatomy and our experience, we are able to illustrate the safety and utility of this technique. The literature strongly supports the oncologic safety of these methods. This review also supports the use of these techniques as a surgical approach to any mastectomy, with or without reconstruction, and addresses many of the factors involved in improving and maximizing outcomes. While, there are multiple and equally efficacious approaches to mastectomy, several surgical techniques can be used to improve outcomes and ensure optimal flap viability.

Precision biopsy of breast microcalcifications: An improvement in surgical excision

The aim of the present study was to improve the conventional wire-guided localization biopsy (WGLB) of breast microcalcifications to overcome disadvantages associated with the procedure, including inaccurate localization and large specimen volume. The novel approach described in the present study was termed double wire-guided localization and rotary cutting biopsy (DWGLB). Prior to surgery, the precise localization of the lesions was assessed using two wires under the assistance of mammography X-ray and ultrasound, followed by complete excision of the lesions using a novel rotary cutting tool. The cylindrical specimen was placed on a scaled specimen holder for pathological examination. DWGLB was performed in 108 patients with the classification of as Breast Imaging Reporting and Data System score 4A. Percutaneous localization of the lesions guided by a mammography X-ray and ultrasound were successful in all 108 lesions (100%) with one puncture attempt. The lesions were precisely excised in all of 108 patients, and included 13 malignant lesions (DCIS of breast in 7 cases, DCIS with focal invasive carcinoma in 3 cases and invasive ductal carcinoma in 3 cases). The average distance of the BARD Dualok to the lesion was 4.1 mm; the average weight of specimens was 8.5 g. Compared with WGLB, DWGLB offers several advantages, including more accurate localization of lesions, a more standardized biopsy method and a smaller specimen volume. DWGLB can also provide the precise position of lesions in the specimen for further pathological examination.

Stereoscopic digital mammogram: Usefulness in daily practice

OBJECTIVES

To assess the benefit of stereoscopic digital mammography in daily practice.

METHODS

Stereoscopic digital (SD) mammography allows a fused 3D view of mammogram. A 4-degree cranio-caudal (CC) angle view matched with a regular CC view allows generating a stereoscopic view. Three breast radiologists reviewed retrospectively 1110 stereoscopic digital mammograms (1075 women) performed between November 2011 and February 2013 with the following sequence: each evaluated firstly conventional mammogram alone, and then integrated SD mammograms. The benefit was quoted in 3-grade scale: 0 for no benefit, 1 moderate and 2 excellent. The concordance between radiologists was evaluated by the W Randall coefficient. Subgroup analysis according to the BI-RADS classification, breast density and type of abnormalities were performed by calculating odds-ratio.

RESULTS

The readers had the same opinion regarding the value of stereoscopic digital mammograms in 87% of cases (962/1110). Benefit was null, moderate and excellent in 8, 52 and 26% respectively. The concordance of radiologists was excellent with a W coefficient above 0.89.

CONCLUSIONS

SD mammogram improved interpretation of abnormal mammograms. This potentially interesting and promising complementary tool might be beneficial in daily breast imaging practice.

Comparison and Combination of Strain and Shear Wave Elastography of Breast Masses for Differentiation of Benign and Malignant Lesions by Quantitative Assessment: Preliminary Study

OBJECTIVES

To compare the diagnostic performance of strain and shear wave elastography of breast masses for quantitative assessment in differentiating benign and malignant lesions and to evaluate the diagnostic accuracy of combined strain and shear wave elastography.

METHODS

Between January and February 2016, 37 women with 45 breast masses underwent both strain and shear wave ultrasound (US) elastographic examinations. The American College of Radiology Breast Imaging Reporting and Data System (BI-RADS) final assessment on B-mode US imaging was assessed. We calculated strain ratios for strain elastography and the mean elasticity value and elasticity ratio of the lesion to fat for shear wave elastography. Diagnostic performances were compared by using the area under the receiver operating characteristic curve (AUC).

RESULTS

The 37 women had a mean age of 47.4 years (range, 20-79 years). Of the 45 lesions, 20 were malignant, and 25 were benign. The AUCs for elasticity values on strain and shear wave elastography showed no significant differences (strain ratio, 0.929; mean elasticity, 0.898; and elasticity ratio, 0.868; P > .05). After selectively downgrading BI-RADS category 4a lesions based on strain and shear wave elastographic cutoffs, the AUCs for the combined sets of B-mode US and elastography were improved (B-mode + strain, 0.940; B-mode + shear wave; 0.964; and B-mode, 0.724; P < .001). Combined strain and shear wave elastography showed significantly higher diagnostic accuracy than each individual elastographic modality (P = .031).

CONCLUSIONS

These preliminary results showed that strain and shear wave elastography had similar diagnostic performance. The addition of strain and shear wave elastography to B-mode US improved diagnostic performance. The combination of strain and shear wave elastography results in a higher diagnostic yield than each individual elastographic modality.

Breast cancer screening: Where have we been and where are we going? A personal perspective based on history, data and experience

It is important to understand the history of breast cancer screening to better understand the continuing effort to reduce access to screening. Since the randomized, controlled trials have shown a statistically significant mortality reduction for women ages 40-74, the appropriate threshold for initiating screening is age 40 with no data to support the use of the age of 50 as a threshold for screening. All women are at risk for developing breast cancer and all women should have access to screening.

Mammography screening: A major issue in medicine

Breast cancer mortality is declining in most high-income countries. The role of mammography screening in these declines is much debated. Screening impacts cancer mortality through decreasing the incidence of number of advanced cancers with poor prognosis, while therapies and patient management impact cancer mortality through decreasing the fatality of cancers. The effectiveness of cancer screening is the ability of a screening method to curb the incidence of advanced cancers in populations. Methods for evaluating cancer screening effectiveness are based on the monitoring of age-adjusted incidence rates of advanced cancers that should decrease after the introduction of screening. Likewise, cancer-specific mortality rates should decline more rapidly in areas with screening than in areas without or with lower levels of screening but where patient management is similar. These two criteria have provided evidence that screening for colorectal and cervical cancer contributes to decreasing the mortality associated with these two cancers. In contrast, screening for neuroblastoma in children was discontinued in the early 2000s because these two criteria were not met. In addition, overdiagnosis - i.e. the detection of non-progressing occult neuroblastoma that would not have been life-threatening during the subject's lifetime - is a major undesirable consequence of screening. Accumulating epidemiological data show that in populations where mammography screening has been widespread for a long time, there has been no or only a modest decline in the incidence of advanced cancers, including that of de novo metastatic (stage IV) cancers at diagnosis. Moreover, breast cancer mortality reductions are similar in areas with early introduction and high penetration of screening and in areas with late introduction and low penetration of screening. Overdiagnosis is commonplace, representing 20% or more of all breast cancers among women invited to screening and 30-50% of screen-detected cancers. Overdiagnosis leads to overtreatment and inflicts considerable physical, psychological and economic harm on many women. Overdiagnosis has also exerted considerable disruptive effects on the interpretation of clinical outcomes expressed in percentages (instead of rates) or as overall survival (instead of mortality rates or stage-specific survival). Rates of radical mastectomies have not decreased following the introduction of screening and keep rising in some countries (e.g. the United States of America (USA)). Hence, the epidemiological picture of mammography screening closely resembles that of screening for neuroblastoma. Reappraisals of Swedish mammography trials demonstrate that the design and statistical analysis of these trials were different from those of all trials on screening for cancers other than breast cancer. We found compelling indications that these trials overestimated reductions in breast cancer mortality associated with screening, in part because of the statistical analyses themselves, in part because of improved therapies and underreporting of breast cancer as the underlying cause of death in screening groups. In this regard, Swedish trials should publish the stage-specific breast cancer mortality rates for the screening and control groups separately. Results of the Greater New York Health Insurance Plan trial are biased because of the underreporting of breast cancer cases and deaths that occurred in women who did not participate in screening. After 17 years of follow-up, the United Kingdom (UK) Age Trial showed no benefit from mammography screening starting at age 39-41. Until around 2005, most proponents of breast screening backed the monitoring of changes in advanced cancer incidence and comparative studies on breast cancer mortality for the evaluation of breast screening effectiveness. However, in an attempt to mitigate the contradictions between results of mammography trials and population data, breast-screening proponents have elected to change the criteria for the evaluation of cancer screening effectiveness, giving precedence to incidence-based mortality (IBM) and case-control studies. But practically all IBM studies on mammography screening have a strong ecological component in their design. The two IBM studies done in Norway that meet all methodological requirements do not document significant reductions in breast cancer mortality associated with mammography screening. Because of their propensity to exaggerate the health benefits of screening, case-control studies may demonstrate that mammography screening could reduce the risk of death from diseases other than breast cancer. Numerous statistical model approaches have been conducted for estimating the contributions of screening and of patient management to reductions in breast cancer mortality. Unverified assumptions are needed for running these models. For instance, many models assume that if screening had not occurred, the majority of screen-detected asymptomatic cancers would have progressed to symptomatic advanced cancers. This assumption is not grounded in evidence because a large proportion of screen-detected breast cancers represent overdiagnosis and hence non-progressing tumours. The accumulation of population data in well-screened populations diminishes the relevance of model approaches. The comparison of the performance of different screening modalities - e.g. mammography, digital mammography, ultrasonography, magnetic resonance imaging (MRI), three-dimensional tomosynthesis (TDT) - concentrates on detection rates, which is the ability of a technique to detect more cancers than other techniques. However, a greater detection rate tells little about the capacity to prevent interval and advanced cancers and could just reflect additional overdiagnosis. Studies based on the incidence of advanced cancers and on the evaluation of overdiagnosis should be conducted before marketing new breast-imaging technologies. Women at high risk of breast cancer (i.e. 30% lifetime risk and more), such as women with BRCA1/2 mutations, require a close breast surveillance. MRI is the preferred imaging method until more radical risk-reduction options are eventually adopted. For women with an intermediate risk of breast cancer (i.e. 10-29% lifetime risk), including women with extremely dense breast at mammography, there is no evidence that more frequent mammography screening or screening with other modalities actually reduces the risk of breast cancer death. A plethora of epidemiological data shows that, since 1985, progress in the management of breast cancer patients has led to marked reductions in stage-specific breast cancer mortality, even for patients with disseminated disease (i.e. stage IV cancer) at diagnosis. In contrast, the epidemiological data point to a marginal contribution of mammography screening in the decline in breast cancer mortality. Moreover, the more effective the treatments, the less favourable are the harm-benefit balance of screening mammography. New, effective methods for breast screening are needed, as well as research on risk-based screening strategies.

The Breast Cancer Screening "Arcade" and the "Whack-A-Mole" Efforts to Reduce Access to Screening

The effort to reduce access to breast cancer screening has been going on for decades. As each piece of misinformation has been published, scientific responses have exposed the fallacies, but then new "alternative facts" are generated. The effort has been compared to the arcade game "Whack-a-Mole" in which one false argument is addressed only to have a new one "pop up" to replace it. This has ranged from the false claim that early detection would have no effect on breast cancer, to the fallacious idea that early detection was leading to early deaths among young women, to the more recent false suggestion that tens of thousands of breast cancers found by mammography would disappear if left undetected. The following is a short review of a number of nonscientifically derived "Moles" that have been "Whacked" by science.

The Canadian National Breast Screening Studies are compromised and their results are unreliable. They should not factor into decisions about breast cancer screening

The Canadian National Breast Screening Studies were compromised by an unblinded allocation process and poor quality mammography. Contrary to the requirement that allocation in a randomized controlled trial (RCT) be blinded to avoid any possible intentional or unintentional subversion of a random allocation, all women in the CNBSS trials underwent a clinical breast examination prior to assignment to the study arm or the usual care arm. Women with abnormal clinical breast examinations were identified, and this information was available to the coordinators who then assigned the women on open lists. It was, therefore, possible to assign women to whichever arm the coordinator chose. Although subversion was likely unintended, a significant number of women with four or more positive axillary lymph nodes were assigned to the screening arm of CNBSS1. This explains why there were more breast cancer deaths among the screened women in the first ten years of the trial and why the 5 year survival of the control women was better than 90% when the background survival in Canada at the time was only 75%. The trials were further compromised by the poor quality of the mammography which was confirmed by a review conducted by the trials' organizers. These fundamental problems compromise the CNBSS and make their results, which are major outliers in the RCT's of breast cancer screening, unreliable. Consequently, they should not be used to establish guidelines for breast cancer screening.

More misinformation on breast cancer screening

Unfortunately, a great deal of misinformation has accumulated in the breast cancer screening literature that is based on flawed analyses in an effort to reduce access to screening. Quite remarkably, much of this has come from publications in previously highly respected medical journals. In several papers the intervention (mammography screening) is faulted yet the analyses provided no data on who participated in mammography screening, and which cancers were detected by mammography screening. It is remarkable that a highly respected journal can fault an intervention with no data on the intervention. Claims of massive over diagnosis of invasive breast cancer due to breast cancer screening have been made using "guesses" that have no scientific basis. No one has ever seen a mammographically detected, invasive breast cancer, disappear on its own, yet analysts have claimed that this occurs thousands of times each year. In fact, the" miraculous" resolution, without intervention, of a handful of breast cancers have all been palpable cancers, yet there is no suggestion to stop treating palpable cancers. A review of several publications in the New England Journal of Medicine shows some of the flaws in these analyses. There is clearly a problem with peer review that is allowing scientifically unsupportable material, which is misleading women and their physicians, to be published in prestigious journals.

Addition of Digital Breast Tomosynthesis to Full-Field Digital Mammography in the Diagnostic Setting: Additional Value and Cancer Detectability

Purpose

The purpose of this study was to assess the value of adding digital breast tomosynthesis (DBT) to full-field digital mammography (FFDM) in the diagnostic workup of breast cancer and to determine which lesion variables affect cancer detectability in the combined modality.

Methods

Between March and May 2012, paired FFDM and DBT images were obtained from 203 women as part of a diagnostic workup for breast cancer. Images from FFDM alone, DBT alone, and DBT combined with FFDM were reviewed in separate sessions by six blinded readers. Jackknife alternative free-response receiver operating characteristic (JAFROC) figure of merit (FOM), sensitivity, and specificity were compared between the modalities. Lesion characteristics affecting the cancer detection rate when using the combined modality were also analyzed.

Results

Among the 203 women, 126 women had a total of 129 malignancies and 77 women had total of 77 benign lesions. The overall JAFROC FOM of the combined modality was higher than that of FFDM alone (0.827 vs. 0.775, p<0.001) and that of DBT alone was higher than that of FFDM alone (0.807 vs. 0.775, p=0.027). The overall sensitivity of the combined modality was higher than that of FFDM alone (80.0% vs. 73.2%, p<0.001) and that of DBT alone was higher than that of FFDM alone (78.3% vs. 73.2%, p=0.007). Compared to FFDM alone, the combined modality detected an additional 48 cancers. Using the combined modality, the presence of masses or microcalcifications was significantly associated with the cancer detection rate (p<0.001).

Conclusion

The combination of DBT with FFDM results in a higher diagnostic yield than FFDM alone. Additionally, DBT alone performs better than FFDM alone. However, even when DBT is combined with FFDM, breast cancers with no discernible masses and those lacking calcifications are difficult to detect.

Recent changes in breast cancer incidence and mortality in Estonia: Transition to the west

Background The aim of this study was to examine breast cancer (BC) incidence and mortality trends in Estonia during recent decades and to compare the pattern of these trends with other selected European countries and regions. We attempt to explain the findings in relation to changes in Estonian society and healthcare system. Methods BC incidence (1985-2012) and mortality (1985-2013) data for Estonia were obtained from the Estonian Cancer Registry and Statistics Estonia. Data for selected European countries were obtained from the EUREG database. Joinpoint regression was used to analyze age-standardized rates in Estonia by age. For international comparison of incidence and mortality rates, we used scatterplot with 95% confidence ellipses and the mortality to incidence ratio. Results The overall BC incidence continues to increase in Estonia, while mortality has been in decline since 2000. Both incidence and mortality trends varied considerably across age groups. Among women aged 60 years and older, BC incidence increased at a rate of nearly 3% per year. Significant decrease in mortality was seen only among women aged 50-59 years. Comparison of scatterplots between countries and regions revealed two clusters in Europe separated along the incidence axis. The correlation between incidence and mortality in Estonia changed its direction in the mid-1990s. Conclusion In recent years, the dynamics of BC burden in Estonia has transitioned towards the high incidence-low mortality type model, which is characteristic to Western, Northern and Southern Europe. Although overall BC incidence is much lower in Estonia than in more affluent European countries, mortality from BC is still relatively high, particularly among elderly women.

Impact of organised mammography screening on breast cancer mortality in a case-control and cohort study

BACKGROUND

The usefulness of case-control studies has been questioned. Our aim was to evaluate the long-term effect of screening on breast cancer mortality within the population-based mammography programme in Finland using a case-control design, and to compare the analyses with the earlier cohort study.

METHODS

The cases were women invited to screening, diagnosed and died from breast cancer in 1992-2011 while being 50-84 years at death. We chose 10 controls for each case with non-restrictive eligibility criteria. Our data included 1907 cases and 18 978 matched controls. We analysed associations between the screening participation and the risk of breast cancer death using the conditional Cox proportional hazards model. The effect estimates were corrected for self-selection bias.

RESULTS

An overall effect of screening was 0.67 (95% confidence interval (CI): 0.49-0.90), and that remained unchanged over time. Analyses with matching criteria comparable to the cohort study yielded an effect (0.70, 95% CI: 0.49-1.00) in 1992-2003 similar to that of the previous cohort analysis (0.72, 95% CI: 0.56-0.88).

CONCLUSIONS

Organised mammography screening decreases mortality from breast cancer by 33% among the participants. If made comparable, a case-cohort study can yield effect estimates similar to a cohort study.

Breast cancer screening panels continue to confuse the facts and inject their own biases

Additional confusion has been added to the “debate” about breast cancer. [...]

Increased Cancer Detection Rate and Variations in the Recall Rate Resulting from Implementation of 3D Digital Breast Tomosynthesis into a Population-based Screening Program

PURPOSE

To compare the recall and cancer detection rates (CDRs) at screening with digital breast tomosynthesis (DBT) with those at screening with two-dimensional (2D) mammography and to evaluate variations in the recall rate (RR) according to patient age, risk factors, and breast density and among individual radiologists at a single U.S. academic medical center.

MATERIALS AND METHODS

This institutional review board-approved, HIPAA-compliant prospective study with a retrospective cohort included 85 852 asymptomatic women who presented for breast cancer screening over a 3-year period beginning in 2011. A DBT unit was introduced into the existing 2D mammography screening program, and patients were assigned to the first available machine. Ten breast-subspecialized radiologists interpreted approximately 90% of the examinations. RRs were calculated overall and according to patient age, breast density, and individual radiologist. CDRs were calculated. Single and multiple mixed-effect logistic regression analyses, χ(2) tests, and Bonferroni correction were utilized, as appropriate.

RESULTS

The study included 5703 (6.6%) DBT examinations and 80 149 (93.4%) 2D mammography examinations. The DBT subgroup contained a higher proportion of patients with risk factors for breast cancer and baseline examinations. DBT was used to detect 54.3% more carcinomas (+1.9 per 1000, P < .0018) than 2D mammography. The RR was 7.51% for 2D mammography and 6.10% for DBT (absolute change, 1.41%; relative change, -18.8%; P < .0001). The DBT subgroup demonstrated a significantly lower RR for patients with extremely or heterogeneously dense breasts and for patients in their 5th and 7th decades.

CONCLUSION

Implementing DBT into a U.S. breast cancer screening program significantly decreased the screening RR overall and for certain patient subgroups, while significantly increasing the CDR. These findings may encourage more widespread adoption and reimbursement of DBT and facilitate improved patient selection.

An open letter to panels that are deciding guidelines for breast cancer screening

Panels are presently reviewing breast cancer screening guidelines. It is critical that they understand which publications are scientifically valid, and which analyses are methodologically flawed and not valid. The scientific evidence clearly supports annual mammography screening beginning at the age of 40. The analyses that suggest that screening leads to overdiagnosis of invasive breast cancers are flawed and incorrect. There is little if any overdiagnosis of these cancers. The vast majority of breast cancers occur in women who are not at elevated risk so that excluding them from screening and only screening high risk women will deny the benefits of early detection to most women who develop breast cancer. Guidelines panels should not make decisions that exclude women from screening. Women should be provided with accurate information so that they can make informed decisions and have unimpeded access to screening if that is their preference.

Breast cancer in European Union: an update of screening programmes as of March 2014 (review)

Breast cancer, a major cause of female morbidity and mortality, is a global health problem; 2008 data show an incidence of ~450,000 new cases and 140,000 deaths (mean incidence rate 70.7 and mortality rate 16.7, world age-standardized rate per 100,000 women) in European Union Member States. Incidence rates in Western Europe are among the highest in the world. We review the situation of BC screening programmes in European Union. Up to date information on active BC screening programmes was obtained by reviewing the literature and searching national health ministries and cancer service websites. Although BC screening programmes are in place in nearly all European Union countries there are still considerable differences in target population coverage and age and in the techniques deployed. Screening is a mainstay of early BC detection whose main weakness is the rate of participation of the target population. National policies and healthcare planning should aim at maximizing participation in controlled organized screening programmes by identifying and lowering any barriers to adhesion, also with a view to reducing healthcare costs.

Influence of service characteristics on high priority performance indicators and standards in the BreastScreen Australia program

BACKGROUND

Data from BreastScreen Australia Screening and Assessment Services (SAS) for 2002-2010 were analysed to determine whether some SAS characteristics were more conducive that others to high screening performance, as indicated by high priority performance indicators and standards.

MATERIALS AND METHODS

Indicators investigated related to: numbers of benign open biopsies, screen-detected invasive cancers, and interval cancers, and wait times between screening and assessment. Multivariate Poisson regression was undertaken using as candidate predictors of performance, SAS size (screening volume), urban or rural location, year of screening, accreditation status, and percentages of clients from culturally and linguistically diverse backgrounds, rural and remote areas, and socio-economically disadvantaged areas.

RESULTS

Performance standards for benign biopsies and invasive cancer detection were uniformly met irrespective of SAS location and size. The interval cancer standard was also met, except in 2003 when the 95% confidence interval of the rate still incorporated the national standard. Performance indicators improved over time for: benign open biopsy for second or subsequent screening rounds; rates of invasive breast cancer detection for second or subsequent screening rounds; and rates of small cancer detection. No differences were found over time in interval cancer rates. Interval cancer rates did not differ between non-metropolitan and metropolitan SAS, although state-wide SAS had lower rates. The standard for wait time between screening and assessment (being assessed <28 days) was mostly unmet and this applied in particular to SAS with high percentages of culturally and linguistically diverse women in their screening populations.

CONCLUSIONS

Gains in performance were observed, and all performance standards were met irrespective of SAS characteristics, except wait times to assessment. Additional descriptive data should be collected on SAS characteristics, and their associations with favourable screening performance, as these may be important when deciding on SAS design.

Screening mammography benefit controversies: sorting the evidence

Numerous clinical studies have confirmed that screening women age 40 years and older reduces breast cancer mortality by 30% to 50%. Several factors including faster breast cancer growth rates and lower breast cancer incidence among younger women, as well as shorter life expectancy and more comorbid conditions among older women, should also be considered in screening guidelines. Annual screening beginning at age 40 years and continuing with no upper age limit, as long as a woman has a life expectancy of at least 5 years and no significant comorbid conditions, is currently recommended.

Breast cancer screening halves the risk of breast cancer death: a case-referent study

Large-scale epidemiologic studies have consistently demonstrated the effectiveness of mammographic screening programs, however the benefits are still subject to debate. We estimated the effect of the Dutch screening program on breast cancer mortality. In a large multi-region case-referent study, we identified all breast cancer deaths in 2004 and 2005 in women aged 50-75 who had been invited for screening (cases). Cases were individually matched to referents from the population invited to screening. Conditional logistic regression was used to estimate the odds ratio (OR) of breast cancer death according to individual screening history. The OR was adjusted for self-selection bias using regional correction factors for the difference in baseline risk for breast cancer death between screened and unscreened women. A total of 1233 cases and 2090 referents were included in this study. We found a 58% reduction in breast cancer mortality in screened versus unscreened women (adjusted OR = 0.42, 95% CI 0.33-0.53). Screening, i.e. early detection and treatment, has resulted in a substantial reduction in breast cancer mortality, indicating that the Dutch breast cancer screening program is highly effective.

Type of breast cancer diagnosis, screening, and survival

INTRODUCTION

Breast cancer screening is known to reduce mortality. In the present study, we analyzed the prevalence of breast cancers detected through screening, before and after introduction of an organized screening, and we evaluated the overall survival of these patients in comparison with women with an extrascreening imaging-detected breast cancer or those with palpable breast cancers.

MATERIALS AND METHODS

We collected data about all women who underwent a breast operation for cancer in our department between 2001 and 2008, focusing on type of tumor diagnosis, tumor characteristics, therapies administered, and patient outcome in terms of overall survival, and recurrences. Data was analyzed by R (version 2.15.2), and P < .05 was considered significant.

RESULTS

Among the 2070 cases of invasive breast cancer we considered, 157 were detected by regional mammographic screening (group A), 843 by extrascreening breast imaging (group B: 507 by mammography and 336 by ultrasound), and 1070 by extrascreening breast objective examination (group C). The 5-year overall survival in groups A, B, and C were, respectively, 99% (95% CI, 98%-100%), 98% (95% CI, 97%-99%), and 91% (95% CI, 90%-93%), with a significant difference between the first 2 groups and the third (P < .05) and a trend between groups A and B (P = .081).

CONCLUSION

The diagnosis of invasive breast cancer with screening in our population resulted in a survival gain at 5 years from the diagnosis, but a longer follow-up is necessary to confirm this data.

Prospective trial comparing full-field digital mammography (FFDM) versus combined FFDM and tomosynthesis in a population-based screening programme using independent double reading with arbitration

OBJECTIVES

To compare double readings when interpreting full field digital mammography (2D) and tomosynthesis (3D) during mammographic screening.

METHODS

A prospective, Ethical Committee approved screening study is underway. During the first year 12,621 consenting women underwent both 2D and 3D imaging. Each examination was independently interpreted by four radiologists under four reading modes: Arm A-2D; Arm B-2D + CAD; Arm C-2D + 3D; Arm D-synthesised 2D + 3D. Examinations with a positive score by at least one reader were discussed at an arbitration meeting before a final management decision. Paired double reading of 2D (Arm A + B) and 2D + 3D (Arm C + D) were analysed. Performance measures were compared using generalised linear mixed models, accounting for inter-reader performance heterogeneity (P < 0.05).

RESULTS

Pre-arbitration false-positive scores were 10.3 % (1,286/12,501) and 8.5 % (1,057/12,501) for 2D and 2D + 3D, respectively (P < 0.001). Recall rates were 2.9 % (365/12,621) and 3.7 % (463/12,621), respectively (P = 0.005). Cancer detection was 7.1 (90/12,621) and 9.4 (119/12,621) per 1,000 examinations, respectively (30 % increase, P < 0.001); positive predictive values (detected cancer patients per 100 recalls) were 24.7 % and 25.5 %, respectively (P = 0.97). Using 2D + 3D, double-reading radiologists detected 27 additional invasive cancers (P < 0.001).

CONCLUSION

Double reading of 2D + 3D significantly improves the cancer detection rate in mammography screening.

KEY POINTS

• Tomosynthesis-based screening was successfully implemented in a large prospective screening trial. • Double reading of tomosynthesis-based examinations significantly reduced false-positive interpretations. • Double reading of tomosynthesis significantly increased the detection of invasive cancers.

Kin KeeperSM: design and baseline characteristics of a community-based randomized controlled trial promoting cancer screening in Black, Latina, and Arab women

BACKGROUND

Although breast and cervical cancer deaths have declined due to early screening, detection, and more effective treatment, racial and ethnic disparities persist. This paper describes the study design and baseline characteristics of a randomized controlled trial (RCT) evaluating the effectiveness of the Kin Keeper(SM) Cancer Prevention Intervention, a family-focused educational intervention for underserved women applied in a community-based setting to promote health literacy and screening adherence to address cancer disparities.

METHODS

Female public health community health workers (CHWs) were trained to administer the intervention. They recruited female clients from their public health program caseload and asked each to assemble two to four adult female family members for the breast and cervical cancer home-based education sessions the CHWs would deliver in English, Spanish or Arabic. We randomized the clients into the kin keeper group (treatment) or the participant client group (control).

RESULTS

Complete data were obtained on 514 Black, Latina, and Arab women. Close to half were unemployed and had yearly family income below $20,000. Thirty-four percent had no medical insurance, and 21% had diabetes. Almost 40% had no mammography in the last year. Treatment and control groups were similar on most sociodemographics but showed differences in breast and cervical screening history.

CONCLUSIONS

This innovative study demonstrates the implementation of an RCT using community-based participatory research, while delivering cancer prevention education across woman's life span with women not connected to the health care system.

The impact of mammographic screening on breast cancer mortality in Europe: a review of observational studies

OBJECTIVES

To assess the impact of population-based mammographic screening on breast cancer mortality in Europe, considering different methodologies and limitations of the data.

METHODS

We conducted a systematic literature review of European trend studies (n = 17), incidence-based mortality (IBM) studies (n = 20) and case-control (CC) studies (n = 8). Estimates of the reduction in breast cancer mortality for women invited versus not invited and/or for women screened versus not screened were obtained. The results of IBM studies and CC studies were each pooled using a random effects meta-analysis.

RESULTS

Twelve of the 17 trend studies quantified the impact of population-based screening on breast cancer mortality. The estimated breast cancer mortality reductions ranged from 1% to 9% per year in studies reporting an annual percentage change, and from 28% to 36% in those comparing post- and prescreening periods. In the IBM studies, the pooled mortality reduction was 25% (relative risk [RR] 0.75, 95% confidence interval [CI] 0.69-0.81) among invited women and 38% (RR 0.62, 95% CI 0.56-0.69) among those actually screened. The corresponding pooled estimates from the CC studies were 31% (odds ratio [OR] 0.69, 95% CI 0.57-0.83), and 48% (OR 0.52, 95% CI 0.42-0.65) adjusted for self-selection.

CONCLUSIONS

Valid observational designs are those where sufficient longitudinal individual data are available, directly linking a woman's screening history to her cause of death. From such studies, the best 'European' estimate of breast cancer mortality reduction is 25-31% for women invited for screening, and 38-48% for women actually screened. Much of the current controversy on breast cancer screening is due to the use of inappropriate methodological approaches that are unable to capture the true effect of mammographic screening.

Breast cancer screening: are we seeing the benefit?

A decline in breast cancer mortality has been observed in western European Countries since the middle of the 1990s. Different methodological approaches, including case-control studies, incidence-based mortality studies, and trend studies, have been used to assess the effectiveness of mammography screening programmes in reducing breast cancer mortality. However, not all methods succeed in distinguishing the relative contributions of service screening and taking correctly into consideration the potential source of bias that might affect the estimate. Recently, a review of six case-control studies confirmed a breast cancer mortality reduction ranging from 38% to 70% among screened women. This figure is in accordance with the estimate obtained from incidence-based mortality studies if screening compliance is taken into account. We will describe the methodological constraints of mortality trend studies in predicting the impact of screening on mortality and the necessary caution that must be applied when interpreting the results of such studies. In conclusion, when appropriate methodological approaches are used, it is evident that mammographic screening programmes have contributed substantially to the observed decline in breast cancer mortality.

Stage-specific breast cancer incidence rates among participants and non-participants of a population-based mammographic screening program

The Norwegian Breast Cancer Screening Program was rolled out county by county over the course of a decade, from 1996 to 2005, and now encompasses all Norwegian women aged 50-69 years. We aim to compare DCIS and stage-specific invasive breast cancer incidence rates among participants, non-participants, and women not yet invited to the screening program over this entire implementation period. We estimate stage-specific breast tumor incidence rates for 640,347 women 50-69 years of age invited to the screening program between 1996 and 2007. We compare incidence rates and stage distribution among women diagnosed with breast cancer who were invited and participated, invited but not participated, and women not yet invited to the screening program using two-sided Chi-squared tests to determine statistical significance between groups. The incidence of ductal carcinoma in situ (DCIS) was 3.0 times higher and invasive breast cancer was 1.5 times higher for invited participants compared to invited non-participants (p < 0.001). While the incidence of Stage I cancer was two times higher among participants compared to non-participants (p < 0.001), the incidences of Stages III and IV cancer were two and three times lower, respectively, among participants compared to non-participants (p < 0.001 for both). No significant differences in stage-specific incidence or treatment utilization rates were observed between invited non-participants and not yet invited women, except for stage IV cancers, which were detected at a higher rate among women who were not yet invited (7.5 vs. 4.6 %, p = 0.001). Compared with women invited who did not participate, participants in the screening program are more likely to be diagnosed with DCIS and early stage invasive breast cancer and are less likely to be diagnosed with advanced stage breast cancer. More research is required to determine whether these differences in stage-specific incidences among invited participants and non-participants are associated with differences in mortality rates.

Balancing harms and benefits of service mammography screening programs: a cohort study

INTRODUCTION

The use of screening mammography is still under debate within the medical community. The aim of this study is to define a balance sheet of benefits (breast cancer mortality reduction) and harms (overdiagnosis) for mammography screening programs.

METHODS

We compared breast cancer incidence and mortality in two cohorts of women, defined as 'attenders' or 'non-attenders' on the basis of the individual attitudes towards screening, who were invited to the first round of the Florentine screening program. The effects of screening exposure on breast cancer incidence and mortality were evaluated by fitting Poisson regression models adjusted for age at entry, marital status and deprivation index. We performed a sensitivity analysis excluding 34 women not responding to the invitation with a breast cancer diagnosis in the following six months.

RESULTS

In total, we included 51,096 women aged 50 to 69 years invited at the first screening round (1991 to 1993) and followed-up for breast cancer incidence and mortality until 31 December 2007 and 31 December 2008, respectively The estimate of mortality reduction varies from 45% among 50 to 59 year-old women up to 51% among 60 to 69 year-old women. The estimate of overdiagnosis, according to the cumulative-incidence method, is an additional 10% of all breast cancer cases among 60 to 69 year-old women screened.

CONCLUSIONS

Comparing the breast cancer mortality and breast cancer incidence between attenders and non-attenders, we have determined that the overall cost to save one life corresponds to no more than one over-diagnosed tumor (from 0.6 to 1 depending on the selection criteria of the cohort), even if a residual self-selection bias cannot be excluded.

Minor influence of self-selection bias on the effectiveness of breast cancer screening in case-control studies in the Netherlands

Background

Self-selection bias is considered to be a problem when evaluating the effectiveness of breast cancer service screening in case-control studies.

Objective

Using the incidence-based mortality method (IBM), a correction factor for the potential influence of self-selection can be derived from a group of non-screened women and a group of not-invited women.

Methods

Breast cancer patients, diagnosed in 1990–1995 and between the ages of 50 to 70, were selected from the Netherlands Cancer Registry and five screening regions in the Netherlands. Person-years were calculated for non-screened and not-invited women by using population data available on the number of women invited, the number of women screened and the total population. Incidence-based breast cancer mortality rates according to screening status were calculated for the five screening regions.

Results

Between 1990–1995, 15,541 patients were diagnosed with breast cancer. An analysis of ten-year follow-up after diagnosis resulted in 3903 breast cancer deaths, of which 2631 were not-invited and 345 were non-screened. Poisson regression analysis showed heterogeneity between the regions with a range of IBM ratios from 0.64 (95% CI: 0.46–0.90) to 1.08 (95% CI: 0.82–1.43).

Conclusions

Heterogeneity between the regions stresses the importance of a country- and/or region-specific estimate of self-selection. Adjusting for self-selection bias in the regional case-control studies would not change the breast cancer mortality reduction in three regions and would result in an even larger effect in two regions. Looking at the range of IBM ratios the overall influence of self-selection in the Netherlands is minor.

Population studies of the effectiveness of mammographic screening

OBJECTIVE

To examine population data to see whether survival from breast cancer has improved differentially in screened and unscreened women and examine published studies on mammographic screening to determine whether there is evidence that screening is no longer effective.

METHODS

Data was reviewed on trends in breast cancer specific survival among women participating and not participating in the British Columbia Breast Screening Program. Population studies of mammographic screening published between 2000 and 2010 with breast cancer mortality as the outcome were also reviewed.

RESULTS

Breast cancer specific survival in British Columbia improved more in screening participants than non-participants, HR=0.74 (0.58,0.93) between the periods 1990-4 and 2000-4. Among the published studies of mortality between 2000 and 2010 selected from different jurisdictions all had found a reduction in breast cancer mortality although this was not always statistically different from zero. Studies had used a range of designs and evaluative methods which may have contributed to the magnitude of the effect reported.

CONCLUSION

No evidence was found in the British Columbia data and the published studies reviewed, that treatment or other changes, had caused mammographic screening to become ineffective.

Residual confounding after adjustment for age: a minor issue in breast cancer screening effectiveness

Residual confounding, after adjustment for age, is the major criticism of observational studies on breast cancer screening effectiveness. We developed realistic scenarios for the prevalence and strength of risk factors on screened and not screened groups, and explored the impact of residual confounding bias. Our results demonstrate that residual confounding bias is a minor issue in screening programme evaluations.