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Background: The incidence of ductal carcinoma in situ (DCIS) has rapidly increased over time. The malignant potential of DCIS is dependent on its differentiation grade., Methods: Our aim is to determine the distribution of different grades of DCIS among women screened in the mass screening programme, and women not screened in the mass screening programme, and to estimate the amount of overdiagnosis by grade of DCIS. We retrospectively included a population-based sample of 4232 women with a diagnosis of DCIS in the years 2007-2009 from the Nationwide network and registry of histopathology and cytopathology in the Netherlands. Excluded were women with concurrent invasive breast cancer, lobular carcinoma in situ and no DCIS, women recently treated for invasive breast cancer, no grade mentioned in the record, inconclusive record on invasion, and prevalent DCIS. The screening status was obtained via the screening organisations. The distribution of grades was incorporated in the well-established and validated microsimulation model MISCAN., Results: Overall, 17.7 % of DCIS were low grade, 31.4 % intermediate grade, and 50.9 % high grade. This distribution did not differ by screening status, but did vary by age. Older women were more likely to have low-grade DCIS than younger women. Overdiagnosis as a proportion of all cancers in women of the screening age was 61 % for low-grade, 57 % for intermediate-grade, 45 % for high-grade DCIS. For women age 50-60 years with a high-grade DCIS this overdiagnosis rate was 21-29 %, compared to 50-66 % in women age 60-75 years with high-grade DCIS., Conclusions: Amongst the rapidly increasing numbers of DCIS diagnosed each year is a significant number of overdiagnosed cases. Tailoring treatment to the probability of progression is the next step to preventing overtreatment. The basis of this tailoring could be DCIS grade and age.

Background: To determine whether referred women experience differences in diagnostic workup at non-blinded or blinded double reading of screening mammograms., Methods: We included a consecutive series of respectively 42.996 and 44.491 screens, double read either in a non-blinded or blinded manner between 2009 and 2011. This reading strategy was alternated on a monthly basis., Results: The overall ultrasound-guided core needle biopsy (CNB) rate and stereotactic CNB (SCNB) rate per 1000 screens were higher at blinded than at non-blinded reading (7.5 vs 6.0, P=0.008 and 8.1 vs 6.6, P=0.009). Among women with benign workup, these rates were higher at blinded reading (2.6 vs 1.4, P<0.001 and 5.9 vs 4.7, P=0.013). The benign biopsy rates were higher at blinded double reading (P<0.001), whereas the positive predictive value of biopsy did not differ (P=0.103)., Conclusions: Blinded double-reading results in higher overall CNB and SCNB rates than non-blinded double reading, as well as a higher benign biopsy rate.

Background: Lifetime risks are often used in communications on cancer to the general public. The most-cited estimate for breast cancer risk (1 in 8 women), however, appears to be outdated. Here we describe the breast cancer burden in the Netherlands over time by means of lifetime and age-conditional risks. The aim is to identify changes in absolute risk of primary breast cancer diagnosis and death., Methods: Data on breast cancer incidence, mortality and size of the female population were retrieved from the Netherlands Cancer Registry and Statistics Netherlands. Lifetime and age-conditional risks were calculated for 1990, 2000 and 2010 using the life-table method (DevCan software)., Results: The lifetime risk of developing breast cancer (ductal carcinoma in situ and invasive) in 1990, 2000 and 2010 was estimated at 10.8 (1 in 9.3 women), 13.5 (1 in 7.4) and 15.2% (1 in 6.6), respectively. Most women were still diagnosed after the age of 50, with the highest risk between 60 and 70 years in 2010. The lifetime risk of breast cancer death was 3.8% (1 in 27) in 2010, which is lower than in 1990 (4.5%; 1 in 22) and 2000 (4.2%; 1 in 24)., Conclusion: Breast cancer risk has increased to 1 in 6.6 women being diagnosed during their lifetime (invasive cancer only: 1 in 7.4), whereas risk of breast cancer death has decreased from 1 in 22 to 1 in 27 women. To keep cancer management and prevention up-to-date, it remains important to closely monitor the ever-changing breast cancer burden., (© The Author 2014. Published by Oxford University Press on behalf of the European Public Health Association. All rights reserved.)

Purpose: To prospectively determine the screening mammography outcome at blinded and non-blinded double reading in a biennial population based screening programme in the south of the Netherlands., Methods: We included a consecutive series of 87,487 digital screening mammograms, obtained between July 2009 and July 2011. Screening mammograms were double read in either a blinded (2nd reader was not informed about the 1st reader's decision) or non-blinded fashion (2nd reader was informed about the 1st reader's decision). This reading strategy was alternated on a monthly basis. Women with discrepant readings between the two radiologists were always referred for further analysis. During 2 years follow-up, we collected the radiology reports, surgical correspondence and pathology reports of all referred women and interval breast cancers., Results: Respectively 44,491 and 42,996 screens had been read either in a blinded or non-blinded fashion. Referral rate (3.3% versus 2.8%, p<0.001) and false positive rate (2.6% versus 2.2%, p=0.002) were significantly higher at blinded double reading whereas the cancer detection rate per 1000 screens (7.4 versus 6.5, p=0.14) and positive predictive value of referral (22% versus 23%, p=0.51) were comparable. Blinded double reading resulted in a significantly higher programme sensitivity (83% versus 76%, p=0.01). Per 1000 screened women, blinded double reading would yield 0.9 more screen detected cancers and 0.6 less interval cancers than non-blinded double reading, at the expense of 4.4 more recalls., Conclusion: We advocate the use of blinded double reading in order to achieve a better programme sensitivity, at the expense of an increased referral rate and false positive referral rate., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

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., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Objective: Increased recall rates in the Dutch breast cancer screening program call for a new assessment strategy aiming to reduce unnecessary costs and anxiety. Diagnostic work-up (usual care) includes multidisciplinary hospital assessment and is similar for all recalled women, regardless of the radiologist's suspicion of breast cancer. This is similar in many Canadian settings. We developed a novel assessment strategy that offers women with a low suspicion of breast cancer a quick and non-invasive assessment by a screening radiologist (intervention). We compared these two strategies in a cost-effectiveness analysis based on a randomized controlled trial: multicentre randomized controlled trial (MASS trial, Netherlands National Trial Register: NTR1480)., Methods: Participants were enrolled between August 2010 and December 2012 and were randomly assigned to either the intervention or control group (allocation ratio 2:1). Fourteen assessment centres participated in the study. Questionnaires were used to record quality of life (EuroQol-5D), health care use and costs after recall., Results: Our study comprised 366 women, of whom 288 were randomly assigned to the intervention group and 88 to the control group. The mean difference in cost was €153/CAD $226 (95% confidence interval €107-199/CAD $158-294, p&lt;0.001). We found no significant differences in quality of life. The bootstrapped incremental cost-effectiveness ratios in the cost-effectiveness plane showed that the intervention was the efficient, cost-saving modality., Conclusion: Our data show the benefits of tailoring diagnostic assessment to the screening radiologist's suspicion of breast cancer. Scenarios of implementing such a strategy in the Dutch screening or health care system are currently being discussed with various stakeholders.

A recent comprehensive review has been carried out to quantify the benefits and harms of the European population-based mammographic screening programs. Five literature reviews were conducted on the basis of the observational published studies evaluating breast cancer mortality reduction, breast cancer overdiagnosis, and false-positive results. On the basis of the studies reviewed, the authors present a first estimate of the benefit and harm balance sheet. For every 1,000 women screened biennially from ages 50 to 51 years until ages 68 to 69 years and followed up until age 79 years, an estimated seven to nine breast cancer deaths are avoided, four cases are overdiagnosed, 170 women have at least one recall followed by noninvasive assessment with a negative result, and 30 women have at least one recall followed by invasive procedures yielding a negative result. The chance of a breast cancer death being avoided by population-based mammography screening of appropriate quality is more than that of overdiagnosis by screening. These outcomes should be communicated to women offered service screening in Europe., (©2014 American Association for Cancer Research.)

Purpose: To evaluate a self-test for Dutch breast screening radiologists introduced as part of the national quality assurance programme., Methods and Materials: A total of 144 radiologists were invited to complete a test-set of 60 screening mammograms (20 malignancies). Participants assigned findings such as location, lesion type and BI-RADS. We determined areas under the receiver operating characteristics (ROC) curves (AUC), case and lesion sensitivity and specificity, agreement (kappa) and correlation between reader characteristics and case sensitivity (Spearman correlation coefficients)., Results: A total of 110 radiologists completed the test (76%). Participants read a median number of 10,000 screening mammograms/year. Median AUC value was 0.93, case and lesion sensitivity was 91% and case specificity 94%. We found substantial agreement for recall (κ = 0.77) and laterality (κ = 0.80), moderate agreement for lesion type (κ = 0.57) and BI-RADS (κ = 0.45) and no correlation between case sensitivity and reader characteristics., Conclusion: Areas under the ROC curve, case sensitivity and lesion sensitivity were satisfactory and recall agreement was substantial. However, agreement in lesion type and BI-RADS could be improved; further education might be aimed at reducing interobserver variation in interpretation and description of abnormalities. We offered individual feedback on interpretive performance and overall feedback at group level. Future research will determine whether performance has improved., Key Points: • We introduced and evaluated a self-test for Dutch breast screening radiologists. • ROC curves, case and lesion sensitivity and recall agreement were all satisfactory. • Agreement in BI-RADS interpretation and description of abnormalities could be improved. • These are areas that should be targeted with further education and training. • We offered individual feedback on interpretative performance and overall group feedback.

Purpose: X-ray mammography is the primary tool for early detection of breast cancer and for follow-up after breast conserving therapy (BCT). BCT-treated breasts are smaller, less elastic, and more sensitive to pain. Instead of the current force-controlled approach of applying the same force to each breast, pressure-controlled protocols aim to improve standardization in terms of physiology by taking breast contact area and inelasticity into account. The purpose of this study is to estimate the potential for pressure protocols to reduce discomfort and pain, particularly the number of severe pain complaints for BCT-treated breasts., Methods: A prospective observational study including 58 women having one BCT-treated breast and one untreated nonsymptomatic breast, following our hospital's 18 decanewton (daN) compression protocol was performed. Breast thickness, applied force, contact area, mean pressure, breast volume, and inelasticity (mean E-modulus) were statistically compared between the within-women breast pairs, and data were used as predictors for severe pain, i.e., scores 7 and higher on an 11-point Numerical Rating Scale. Curve-fitting models were used to estimate how pressure-controlled protocols affect breast thickness, compression force, and pain experience., Results: BCT-treated breasts had on average 27% smaller contact areas, 30% lower elasticity, and 30% higher pain scores than untreated breasts (all p < 0.001). Contact area was the strongest predictor for severe pain (p < 0.01). Since BCT-treatment is associated with an average 0.36 dm(2) decrease in contact area, as well as increased pain sensitivity, BCT-breasts had on average 5.3 times higher odds for severe pain than untreated breasts. Model estimations for a pressure-controlled protocol with a 10 kPa target pressure, which is below normal arterial pressure, suggest an average 26% (range 10%-36%) reduction in pain score, and an average 77% (range 46%-95%) reduction of the odds for severe pain. The estimated increase in thickness is +6.4% for BCT breasts., Conclusions: After BCT, women have hardly any choice in avoiding an annual follow-up mammogram. Model estimations show that a 10 kPa pressure-controlled protocol has the potential to reduce pain and severe pain particularly for these women. The results highly motivate conducting further research in larger subject groups.

Background: There is concern about detection of ductal carcinoma in situ (DCIS) in screening mammography. DCIS accounts for a substantial proportion of screen-detected lesions but its effect on breast cancer mortality is debated. The International Cancer Screening Network conducted a comparative analysis to determine variation in DCIS detection., Patients and Methods: Data were collected during 2004-2008 on number of screening examinations, detected breast cancers, DCIS cases and Globocan 2008 breast cancer incidence rates derived from national or regional cancer registers. We calculated screen-detection rates for breast cancers and DCIS., Results: Data were obtained from 15 screening settings in 12 countries; 7,176,050 screening examinations; 29,605 breast cancers and 5324 DCIS cases. The ratio between highest and lowest breast cancer incidence was 2.88 (95% confidence interval (CI) 2.76-3.00); 2.97 (95% CI 2.51-3.51) for detection of breast cancer; and 3.49 (95% CI 2.70-4.51) for detection of DCIS., Conclusions: Considerable international variation was found in DCIS detection. This variation could not be fully explained by variation in incidence nor in breast cancer detection rates. It suggests the potential for wide discrepancies in management of DCIS resulting in overtreatment of indolent DCIS or undertreatment of potentially curable disease. Comprehensive cancer registration is needed to monitor DCIS detection. Efforts to understand discrepancies and standardise management may improve care., (Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Objectives: To develop a prediction model for breast cancer based on common mammographic findings on screening mammograms aiming to reduce reader variability in assigning BI-RADS., Methods: We retrospectively reviewed 352 positive screening mammograms of women participating in the Dutch screening programme (Nijmegen region, 2006-2008). The following mammographic findings were assessed by consensus reading of three expert radiologists: masses and mass density, calcifications, architectural distortion, focal asymmetry and mammographic density, and BI-RADS. Data on age, diagnostic workup and final diagnosis were collected from patient records. Multivariate logistic regression analyses were used to build a breast cancer prediction model, presented as a nomogram., Results: Breast cancer was diagnosed in 108 cases (31 %). The highest positive predictive value (PPV) was found for spiculated masses (96 %) and the lowest for well-defined masses (10 %). Characteristics included in the nomogram are age, mass, calcifications, architectural distortion and focal asymmetry., Conclusion: With our nomogram we developed a tool assisting screening radiologists in determining the chance of malignancy based on mammographic findings. We propose cutoff values for assigning BI-RADS in the Dutch programme based on our nomogram, which will need to be validated in future research. These values can easily be adapted for use in other screening programmes., Key Points: • There is substantial reader variability in assigning BI-RADS in mammographic screening. • There are no strict guidelines linking mammographic findings to BI-RADS categories. • We developed a model (nomogram) predicting the presence of breast cancer. • Our nomogram is based on common findings on positive screening mammograms. • The nomogram aims to assist screening radiologists in assigning BI-RADS categories.

The recent introduction of digital breast tomosynthesis into clinical practice requires quality control procedures. In this study we have investigated whether the assessment of the average glandular dose for modelled standard breasts can be performed using a combination of polymethyl methacrylate (PMMA) and polyethylene (PE) slabs that matches standard breast thicknesses. For this purpose the energies absorbed per unit area of the image receptor when imaging standard breasts and PMMA-PE slabs have been matched taking account of both primary and scattered photons. To achieve this a two-step approach was used. Firstly, the behaviour of the scatter-to-primary ratio (SPR) of PMMA-PE phantoms and standard breasts was investigated using Monte Carlo simulations for various conditions. For imaging without an anti-scatter grid, it was found that the values of standard breast and phantom SPR were significantly different and it follows that these differences are relevant when matching the absorbed energy. In the second part, a set of PMMA-PE combinations is proposed which, for dosimetric purposes, can be used to simulate standard breasts in the thickness range 20 to 100 mm. The dosimetric error when using these PMMA-PE slabs was found to be below 6% for thicknesses up to 7 cm and increases to 10% for 10 cm thickness.

Purpose: To compare screen-film mammography with digital mammography in a breast cancer screening program, with a focus on the clinical relevance of detected cancers., Materials and Methods: The study was approved by the regional medical ethics review board. Informed consent was not required. Before the nationwide transition to digital mammography in the Dutch biennial screening program, the performance of digital mammography was studied in three screening regions. For initial screening examinations, mediolateral oblique and craniocaudal views were obtained of each breast. In subsequent examinations, the mediolateral oblique view was standard. A craniocaudal view was added if indicated. Screening outcomes obtained with screen-film mammography and digital mammography, including radiologic and pathologic characteristics, were compared for initial and subsequent examinations., Results: A total of 1,198,493 screening examinations were performed between 2003 and 2007. Recall was indicated in 18 896 cases (screen-film mammography: 2.6% at initial examinations, 1.3% at subsequent examinations; digital mammography: 4.4% at initial examinations, 2.1% at subsequent examinations; P < .001 for both). Breast cancer was diagnosed in 6410 women (detection rate per 1000 women with screen-film mammography: 5.6 at initial examinations, 5.2 at subsequent examinations; detection rate per 1000 women with digital mammography: 6.8 at initial examinations, 6.1 at subsequent examinations; P = .02 and P < .001, respectively). Digital mammography depicted significantly more ductal carcinoma in situ (DCIS) lesions, irrespective of screening round. Invasive carcinoma was detected significantly more often in subsequent examinations, particularly when associated with microcalcifications (P = .047). The distribution of the histopathologic differentiation grades for DCIS and invasive carcinoma were similar with both modalities. However, with digital mammography more high-grade DCIS lesions were detected at subsequent examinations (P = .013)., Conclusion: In a population-based breast screening program, the performance of digital mammography in the detection of DCIS and invasive carcinoma was substantially better than that of screen-film mammography. There is no sign of an increase in detection of low-grade DCIS lesions-indicative of possible overdiagnosis-with digital breast cancer screening. Rather, digital mammography appears to add to the detection of high-grade DCIS., (© RSNA, 2012.)

Introduction: The Breast Imaging Reporting and Data System (BI-RADS) was introduced in the Dutch breast cancer screening programme to improve communication between medical specialists. Following introduction, a substantial variation in the use of the BI-RADS lexicon for final assessment categories was noted among screening radiologists. We set up a dedicated training programme to reduce this variation. This study evaluates whether this programme was effective., Materials and Methods: Two comparable test sets were read before and after completion of the training programme. Each set contained 30 screening mammograms of referred women selected from screening practice. The sets were read by 25 experienced and 30 new screening radiologists. Cohen's kappa (κ) was used to calculate the inter-observer agreement. The BI-RADS 2003 version was implemented in the screening programme as the BI-RADS 2008 version requires the availability of diagnostic work-up, and this is unavailable., Results: The inter-observer agreement of all participating radiologists (n=55) with the expert panel increased from a pre-training κ-value of 0.44 to a post-training κ-value of 0.48 (p=0.14). The inter-observer agreement of the new screening radiologists (n=30) with the expert panel increased from κ=0.41 to κ=0.50 (p=0.01), whereas there was no difference in agreement among the 25 experienced radiologists (from κ=0.48 to κ=0.46, p=0.60)., Conclusion: Our training programme in the BI-RADS lexicon resulted in a significant improvement of agreement among new screening radiologists. Overall, the agreement among radiologists was moderate (guidelines Landis and Koch). This is in line with results found in the literature., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Objectives: To assess the suitability of the Breast Imaging Reporting and Data System (BI-RADS) as a quality assessment tool in the Dutch breast cancer screening programme., Methods: The data of 93,793 screened women in the Amsterdam screening region (November 2005-July 2006) were reviewed. BI-RADS categories, work-up, age, final diagnosis and final TNM classification were available from the screening registry. Interval cancers were obtained through linkage with the cancer registry. BI-RADS was introduced as a pilot in the Amsterdam region before the nationwide introduction of digital mammography (2009-2010)., Results: A total of 1,559 women were referred to hospital (referral rate 1.7 %). Breast cancer was diagnosed in 485 women (detection rate 0.52 %); 253 interval cancers were reported, yielding a programme sensitivity of 66 % and specificity of 99 %. BI-RADS 0 had a lower positive predictive value (PPV, 14.1 %) than BI-RADS 4 (39.1 %) and BI-RADS 5 (92.9 %; P < 0.0001). The number of invasive procedures and tumour size also differed significantly between BI-RADS categories (P < 0.0001)., Conclusion: The significant differences in PPV, invasive procedures and tumour size match with stratification into BI-RADS categories. It revealed inter-observer variability between screening radiologists and can thus be used as a quality assessment tool in screening and as a stratification tool in diagnostic work-up., Key Points: • The BI-RADS atlas is widely used in breast cancer screening programmes. • There were significant differences in results amongst different BI-RADS categories. • Those differences represented the radiologists' degree of suspicion for malignancy, thus enabling stratification of referrals. • BI-RADS can be used as a quality assessment tool in screening. • Training should create more uniformity in applying the BI-RADS lexicon.

Objectives: To determine the influence of local contrast optimisation on diagnostic accuracy and perceived suspiciousness of digital screening mammograms., Methods: Data were collected from a screening region in the Netherlands and consisted of 263 digital screening cases (153 recalled,110 normal). Each case was available twice, once processed with a tissue equalisation (TE) algorithm and once with local contrast optimisation (PV). All cases had digitised previous mammograms. For both algorithms, the probability of malignancy of each finding was scored independently by six screening radiologists. Perceived case suspiciousness was defined as the highest probability of malignancy of all findings of a radiologist within a case. Differences in diagnostic accuracy of the processing algorithms were analysed by comparing the areas under the receiver operating characteristic curves (A(z)). Differences in perceived case suspiciousness were analysed using sign tests., Results: There was no significant difference in A(z) (TE: 0.909, PV 0.917, P = 0.46). For all radiologists, perceived case suspiciousness using PV was higher than using TE more often than vice versa (ratio: 1.14-2.12). This was significant (P <0.0083) for four radiologists., Conclusions: Optimisation of local contrast by image processing may increase perceived case suspiciousness, while diagnostic accuracy may remain similar., Key Points: Variations among different image processing algorithms for digital screening mammography are large. Current algorithms still aim for optimal local contrast with a low dynamic range. Although optimisation of contrast may increase sensitivity, diagnostic accuracy is probably unchanged. Increased local contrast may render both normal and abnormal structures more conspicuous.

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.

Background: Recent case-control studies on the effectiveness of population-based breast cancer screening show differences in the magnitude of breast cancer mortality reduction. We investigated the role played by aspects of the case-control study design on these differences, e.g. the definition of cases and exposure to screening., Material and Methods: We investigated six case-control studies conducted in East Anglia (UK), Wales, Iceland, central and northern Italy, South Australia and The Netherlands., Results: The breast cancer mortality reduction in the different case-control studies ranged from 38% to 70% in the screened versus the nonscreened women. We identified differences in design, e.g. the inclusion or exclusion of the first years of screening, and the correction factor for self-selection bias., Conclusions: Overall, the design of the case-control studies was similar. The differences in the magnitude of breast cancer mortality reductions are therefore unlikely to be caused by variations in the design of the case-control studies. These differences must be due to other factors, like the organisation of the service screening programme and the attendance rate. The reduction in breast cancer mortality estimated in these case-control studies indicates that the impact of current mammographic screening is at least consistent with the effect reported by the former randomised screening trials., (© The Author 2010. Published by Oxford University Press on behalf of the European Society for Medical Oncology.)

Objectives: To investigate the referral pattern after the transition to full-field digital mammography (FFDM) in a population-based breast cancer screening programme., Methods: Preceding the nationwide digitalisation of the Dutch screening programme, an FFDM feasibility study was conducted. Detection and referral rates for FFDM and screen-film mammography (SFM) were compared for first and subsequent screens. Furthermore, radiological characteristics of referrals in digital screening were assessed., Results: A total of 312,414 screening mammograms were performed (43,913 digital and 268,501 conventional), with 4,473 consecutive referrals (966 following FFDM). Initially the FFDM referral rate peaked, and many false-positive results were noted as a consequence of pseudolesions and increased detection of (benign) microcalcifications. A higher overall referral rate was observed in FFDM screening in both first and subsequent examinations (p < .001), with a significant increase in cancer detection (p = .010)., Conclusion: As a result of initial inexperience with digital screening images implementing FFDM in a population-based breast cancer screening programme may lead to a strong, but temporary increase in referral. Dedicated training in digital screening for radiographers and screening radiologists is therefore recommended. Referral rates decrease and stabilise (learning curve effect) at a higher level than in conventional screening, yet with significantly enhanced cancer detection.

Recent case-referent studies in the Nijmegen breast-screening programme have shown a reduction in breast-cancer mortality of approximately 50% due to screening of women aged 65 years and older. In this type of study, however, the results may be biased because of self-selection. The purpose of our present study was to compare the breast-cancer mortality rate in a population invited for screening with that of a reference population from an area without a screening programme. In 1977-1978, 6773 women aged 68-83 years were enrolled in the mammographic screening programme in Nijmegen, The Netherlands. The women were followed up until 31 December, 1990. The reference population consisted of women from the same birth cohort from Arnhem, a neighbouring city without mass screening, for whom the entry date was 1 January, 1978. The ratios of the Nijmegen and Arnhem breast-cancer mortality rates with 95% confidence intervals (CI) were calculated. In the study period, 173 patients were diagnosed with primary breast cancer in Nijmegen vs. 183 in Arnhem; 40 Nijmegen patients had died of breast cancer vs. 51 Arnhem patients. The cumulative mortality-rate ratio was 0.80 (95% CI = 0.53-1.22). In the periods 1978-1981, 1982-1985 and 1986-1990, the mortality rate ratios were 1.44 (95% CI = 0.67-3.10), 081 (95% CI = 0.37-1.79) and 0.53 (95% CI = 0.27-1.04), respectively. After adjustment for the difference in incidence rate that existed between the Nijmegen and Arnhem populations, mammographic screening of women older than 65 can be expected to yield a 40% reduction in breast-cancer mortality after 10 years.

Two-view mammography is generally preferred as an initial screening examination because the number of missed carcinomas and false positive results in one-view mammography is considered too large. The present review was performed to assess the difference in screening quality between one- and two-view mammography. Nineteen previous studies were reviewed and differences in sensitivity as well as specificity between two-view and one-view mammography were calculated. The results ranged from -5.7% to 19.4% (median 3.9%), and 2.7% to 36.1% (median 14.8%), respectively, and indicate a higher screening quality of two-view mammography. However, in the studies considered there is a large variation in study population, screening tests used and assessment of disease outcome, which makes the numerical results less conclusive. None of the studies provided adequate information for deciding whether two-view mammography in baseline screening for breast cancer is preferable to one-view mammography. If a screening programme using one-view mammography has already achieved high sensitivity and specificity, the value of an additional craniocaudal view is only marginal.