Balancing sensitivity and specificity: sixteen year's of experience from the mammography screening programme in Copenhagen, Denmark

Choice of Assessment and Subsequent Risk of Breast Cancer among Women with False-Positive Mammography Screening

Women with false-positive mammography screening results have a two- to four-fold higher risk of breast cancer. This study aimed to investigate if the subsequent risk of breast cancer after a false-positive mammography screening is associated with the received diagnostic assessment. The study population consisted of women who underwent false-positive mammography screening from January 2010 to June 2019. They were categorised into seven groups depending on the elements in the assessment (standard care: additional mammography, ultrasound, and if they had a relevant biopsy). Risks of interval cancer, next-round screen-detected cancer, and long-term breast cancer for non-standard care assessments were compared to standard care assessments using Binomial and Cox regression models. We included 44,279 women with a false-positive result. Invasive assessments that lacked an ultrasound or additional mammography were not more associated with an increased risk of subsequent cancers compared to that of 'all three elements'. The few assessments that included 'only ultrasound' or 'only mammography' resulted in higher relative risks of next-round screen-detected cancer of 1.52 (95% CI: 0.93-2.47) and 1.67 (95% CI: 0.54-5.16), respectively, compared to that of standard care. The increased subsequent risk of breast cancer among women with a previous false-positive result was not found to be correlated with the choice of elements in the assessment process.

Long-term risk of screen-detected and interval breast cancer after false-positive results at mammography screening: joint analysis of three national cohorts

BACKGROUND

We assessed the long-term risk of screen-detected and interval breast cancer in women with a first or second false-positive screening result.

METHODS

Joint analysis had been performed using individual-level data from three population-based screening programs in Europe (Copenhagen in Denmark, Norway, and Spain). Overall, 75,513 screened women aged 50-69 years from Denmark (1991-2010), 556,640 from Norway (1996-2008), and 517,314 from Spain (1994-2010) were included. We used partly conditional Cox hazards models to assess the association between false-positive results and the risk of subsequent screen-detected and interval cancer.

RESULTS

During follow-up, 1,149,467 women underwent 3,510,450 screening exams, and 10,623 screen-detected and 5700 interval cancers were diagnosed. Compared to women with negative tests, those with false-positive results had a two-fold risk of screen-detected (HR = 2.04, 95% CI: 1.93-2.16) and interval cancer (HR = 2.18, 95% CI: 2.02-2.34). Women with a second false-positive result had over a four-fold risk of screen-detected and interval cancer (HR = 4.71, 95% CI: 3.81-5.83 and HR = 4.22, 95% CI: 3.27-5.46, respectively). Women remained at an elevated risk for 12 years after the false-positive result.

CONCLUSIONS

Women with prior false-positive results had an increased risk of screen-detected and interval cancer for over a decade. This information should be considered to design personalised screening strategies based on individual risk.

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

Objective

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

Methods

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

Results

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

Conclusion

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

Societal costs and effects of implementing population-based mammography screening in Greenland

With a low breast cancer incidence and low population density, Greenland is geographically and organisationally challenged in implementing a cost effective breast cancer screening programme where a large proportion of the Greenlandic women will have to travel far to attend. The aim of this paper is to evaluate the cost effectiveness and cost utility of different strategies for implementing population-based breast cancer screening in Greenland. Two strategies were evaluated: Centralised screening in the capital Nuuk and decentralised screening in the five municipal regions of Greenland. A cost effectiveness and cost utility analysis were performed from a societal perspective to estimate the costs per years of life saved and per QALY gained. Two accommodation models for the women's attendance were examined; accommodation in ordinary hotels or in patient hotels. The least costly accommodation model was the hotel model compared with the patient hotel model, regardless of screening strategy. The decentralised strategy was more cost effective compared with the centralised strategy, resulting in 0.5 million DKK per years of life saved (YLS) and 4.1 million DKK per quality-adjusted life year (QALY) gained within the hotel model. These ratios are significantly higher compared with findings from other countries. The sensitivity analysis showed a substantial gap between the most and least favourable model assumptions. The investigated strategies were all estimated to be extremely costly, mostly due to high transportation and accommodation costs and loss of productivity, and none would be accepted as cost-effective per YLS/QALY gained within a conventional threshold level. The least expensive strategy was regional screening with hotel accommodation.

Mammographic density and structural features can individually and jointly contribute to breast cancer risk assessment in mammography screening: a case-control study

Background

Mammographic density is a well-established risk factor for breast cancer. We investigated the association between three different methods of measuring density or parenchymal pattern/texture on digitized film-based mammograms, and examined to what extent textural features independently and jointly with density can improve the ability to identify screening women at increased risk of breast cancer.

Methods

The study included 121 cases and 259 age- and time matched controls based on a cohort of 14,736 women with negative screening mammograms from a population-based screening programme in Denmark in 2007 (followed until 31 December 2010). Mammograms were assessed using the Breast Imaging-Reporting and Data System (BI-RADS) density classification, Tabár’s classification on parenchymal patterns and a fully automated texture quantification technique. The individual and combined association with breast cancer was estimated using binary logistic regression to calculate Odds Ratios (ORs) and the area under the receiver operating characteristic (ROC) curves (AUCs).

Results

Cases showed significantly higher BI-RADS and texture scores on average than controls (p < 0.001). All three methods were individually able to segregate women into different risk groups showing significant ORs for BI-RADS D3 and D4 (OR: 2.37; 1.32–4.25 and 3.93; 1.88–8.20), Tabár’s PIII and PIV (OR: 3.23; 1.20–8.75 and 4.40; 2.31–8.38), and the highest quartile of the texture score (3.04; 1.63–5.67). AUCs for BI-RADS, Tabár and the texture scores (continuous) were 0.63 (0.57–0–69), 0.65 (0.59–0–71) and 0.63 (0.57–0–69), respectively. Combining two or more methods increased model fit in all combinations, demonstrating the highest AUC of 0.69 (0.63-0.74) when all three methods were combined (a significant increase from standard BI-RADS alone).

Conclusion

Our findings suggest that the (relative) amount of fibroglandular tissue (density) and mammographic structural features (texture/parenchymal pattern) jointly can improve risk segregation of screening women, using information already available from normal screening routine, in respect to future personalized screening strategies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2450-7) contains supplementary material, which is available to authorized users.

Risk of breast cancer after false-positive results in mammographic screening

Women with false-positive results are commonly referred back to routine screening. Questions remain regarding their long-term outcome of breast cancer. We assessed the risk of screen-detected breast cancer in women with false-positive results. We conducted a joint analysis using individual level data from the population-based screening programs in Copenhagen and Funen in Denmark, Norway, and Spain. Overall, 150,383 screened women from Denmark (1991-2008), 612,138 from Norway (1996-2010), and 1,172,572 from Spain (1990-2006) were included. Poisson regression was used to estimate the relative risk (RR) of screen-detected cancer for women with false-positive versus negative results. We analyzed information from 1,935,093 women 50-69 years who underwent 6,094,515 screening exams. During an average 5.8 years of follow-up, 230,609 (11.9%) women received a false-positive result and 27,849 (1.4%) were diagnosed with screen-detected cancer. The adjusted RR of screen-detected cancer after a false-positive result was 2.01 (95% CI: 1.93-2.09). Women who tested false-positive at first screen had a RR of 1.86 (95% CI: 1.77-1.96), whereas those who tested false-positive at third screening had a RR of 2.42 (95% CI: 2.21-2.64). The RR of breast cancer at the screening test after the false-positive result was 3.95 (95% CI: 3.71-4.21), whereas it decreased to 1.25 (95% CI: 1.17-1.34) three or more screens after the false-positive result. Women with false-positive results had a twofold risk of screen-detected breast cancer compared to women with negative tests. The risk remained significantly higher three or more screens after the false-positive result. The increased risk should be considered when discussing stratified screening strategies.

Comparing sensitivity and specificity of screening mammography in the United States and Denmark

Delivery of screening mammography differs substantially between the United States (US) and Denmark. We evaluated whether there are differences in screening sensitivity and specificity. We included screens from women screened at age 50-69 years during 1996-2008/2009 in the US Breast Cancer Surveillance Consortium (BCSC) (n = 2,872,791), and from two population-based mammography screening programs in Denmark (Copenhagen, n = 148,156 and Funen, n = 275,553). Women were followed-up for 1 year. For initial screens, recall rate was significantly higher in BCSC (17.6%) than in Copenhagen (4.3%) and Funen (3.1%). Sensitivity was fairly similar in BCSC (91.8%) and Copenhagen (90.5%) and Funen (92.5%). At subsequent screens, recall rates were 8.8%, 1.8% and 1.4% in BCSC, Copenhagen and Funen, respectively. The BCSC sensitivity (82.3%) was lower compared with that in Copenhagen (88.9%) and Funen (86.9%), but when stratified by time since last screen, the sensitivity was similar. For both initial and subsequent screenings, the specificity of screening in BCSC (83.2% and 91.6%) was significantly lower than that in Copenhagen (96.6% and 98.8%) and Funen (97.9% and 99.2%). By taking time since last screen into account, it was found that American and Danish women had the same probability of having their asymptomatic cancers detected at screening. However, the majority of women free of asymptomatic cancers experienced more harms in terms of false-positive findings in the US than in Denmark.

Comparison of Danish dichotomous and BI-RADS classifications of mammographic density

Background

In the Copenhagen mammography screening program from 1991 to 2001, mammographic density was classified either as fatty or mixed/dense. This dichotomous mammographic density classification system is unique internationally, and has not been validated before.

Purpose

To compare the Danish dichotomous mammographic density classification system from 1991 to 2001 with the density BI-RADS classifications, in an attempt to validate the Danish classification system.

Material and Methods

The study sample consisted of 120 mammograms taken in Copenhagen in 1991–2001, which tested false positive, and which were in 2012 re-assessed and classified according to the BI-RADS classification system. We calculated inter-rater agreement between the Danish dichotomous mammographic classification as fatty or mixed/dense and the four-level BI-RADS classification by the linear weighted Kappa statistic.

Results

Of the 120 women, 32 (26.7%) were classified as having fatty and 88 (73.3%) as mixed/dense mammographic density, according to Danish dichotomous classification. According to BI-RADS density classification, 12 (10.0%) women were classified as having predominantly fatty (BI-RADS code 1), 46 (38.3%) as having scattered fibroglandular (BI-RADS code 2), 57 (47.5%) as having heterogeneously dense (BI-RADS 3), and five (4.2%) as having extremely dense (BI-RADS code 4) mammographic density. The inter-rater variability assessed by weighted kappa statistic showed a substantial agreement (0.75).

Conclusion

The dichotomous mammographic density classification system utilized in early years of Copenhagen’s mammographic screening program (1991–2001) agreed well with the BI-RADS density classification system.

Comparative analysis of breast cancer mortality following mammography screening in Denmark and Norway

BACKGROUND

Denmark and Norway are the best countries to study effects of mammography screening, because they are the only countries with stepwise introduction of nationwide mammography screening, enabling comparative effectiveness studies of high quality. Although Denmark and Norway are countries with similar populations and health care systems, reported reductions in breast cancer mortality (incidence-based) caused by screening differed vastly; 25% in Denmark versus 10% in Norway. This study explores reasons for this difference.

PATIENTS AND METHODS

We compared two published studies from the Danish and Norwegian screening programs (Olsen et al., 2005; Kalager et al., 2010) investigating biennial mammography screening for women age 50-69 years. Four comparison groups of women were constructed ('current' and 'historical screening groups'; 'current' and 'historical nonscreening groups') based on county of residence. We calculated incidence-based breast cancer mortality in the current versus the historical period for screening and nonscreening groups, using mortality rate ratios (MRR) in the two countries, accounting for concomitant changes in breast cancer mortality.

RESULTS

In the screening groups, similar reductions in breast cancer mortality were found when periods preceding and following start of screening were compared, in Denmark [25%; MRR 0.75; 95% confidence interval (CI) 0.64% to 0.88%] and in Norway (28%; MRR 0.72; 95% CI 0.63% to 0.81%). However, mortality increased in Denmark in the current nonscreening group compared with the historical nonscreening group; for women >59 years, breast cancer mortality increased by 14% (MRR 1.14, 95% CI 1.07-1.22), whereas in Norway a 19% reduction was seen (MRR 0.81, 95% CI 0.72-0.92). This increase accounts for the different relative effect of screening in Denmark and Norway; 25% breast cancer mortality reduction in Denmark, 10% in Norway.

CONCLUSIONS

The seemingly larger effect of screening in Denmark may not be solely attributable to screening itself, but to increased breast cancer mortality in women older than 59 years not invited to screening.

Variation in detection of ductal carcinoma in situ during screening mammography: a survey within the International Cancer Screening Network

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.

Mammographic density in birth cohorts of Danish women: a longitudinal study

BACKGROUND

Breast cancer is the leading malignant disease among western women with incidence increasing over time. High mammographic density is a well-established risk factor for breast cancer. We explored trends in mammographic density across birth cohorts to gain further insight into possible time trends in women's mammographic density that might explain the historical increase in breast cancer incidence.

METHODS

Data derived from two mammography screening programs in Denmark from 1991 to 2001, including on average 41,091 women from Copenhagen and 52,938 women from Funen aged 50-69. Mammographic density was assessed qualitatively (fatty or mixed/dense) by senior screening radiologists. The proportion of women with mixed/dense mammographic density was calculated by age at screening, screening period, and birth cohort. The Generalized Estimating Equations were used to calculate odds ratios and 95% confidence intervals. All statistical tests were two-sided.

RESULTS

The proportion of women with mixed/dense mammographic density increased from 45% among women born in the 1920s to 75-80% among women born in the 1940s. In Copenhagen, the age-adjusted odds ratio (95% CI) of mixed/dense mammographic density in women born in 1941-42 was 2.48 (2.22-2.76) compared with women born in 1921-22. In Funen, the age-adjusted odds ratio of mixed/dense mammographic density in women born in 1946-47 was 5.89 (5.32-6.51) compared with women born in 1924-25. Hormone use had a greater impact on mammographic density in birth cohorts of the 1920s compared with those of the 1940s.

CONCLUSIONS

We found suggestive evidence of a birth cohort pattern in mammographic density and an attenuated impact of hormone use in younger compared with older birth cohorts suggesting that postmenopausal mammographic density could be linked to changing exposures accumulated over time in women's lives.

Validating the ability of a single-item assessing drunkenness to detect hazardous drinking

BACKGROUND

To simplify the screening process to identify problem drinking, researchers have developed single-item, quantity-based instruments. Quantity-based items, however, suffer from several limitations.

OBJECTIVE

Determine whether a non-quantity-based single item assessing drunkenness would be able to identify those who exhibited signs of hazardous alcohol use, as determined by Alcohol Use Disorders Identification Test (AUDIT)-C scores.

METHODS

Between September and November of 2011, the alcohol-related behaviors of 1062 self-identified current drinkers were assessed with self-report measures (i.e. AUDIT-C and one item assessing frequency of drunkenness) in addition to corresponding biologic samples (i.e. breath alcohol concentration (BrAC) samples). We assessed the concurrent validity of the single item to identify hazardous alcohol use established via gender-based AUDIT-C thresholds. Convergent validity of the single-item was assessed by determining its relationship to BrAC levels.

RESULTS

The single item accounted for 0.791 of the area under the received operating characteristics curve for hazardous alcohol use (p < 0.001). When employing a cut-off of 1, the single-item question was 95.9% sensitive in identifying hazardous alcohol use.

CONCLUSION

The results reported herein highlight the validity (both concurrent and convergent) and potential utility of a non-quantity-based single-item alcohol screen for assessing drunkenness. Additional research is warranted to confirm the utility of this one-item drunkenness measure to capture risk of injury and hazardous drinking.

Long-term psychosocial consequences of false-positive screening mammography

PURPOSE

Cancer screening programs have the potential of intended beneficial effects, but they also inevitably have unintended harmful effects. In the case of screening mammography, the most frequent harm is a false-positive result. Prior efforts to measure their psychosocial consequences have been limited by short-term follow-up, the use of generic survey instruments, and the lack of a relevant benchmark-women with breast cancer.

METHODS

In this cohort study with a 3-year follow-up, we recruited 454 women with abnormal findings in screening mammography over a 1-year period. For each woman with an abnormal finding on a screening mammogram (false and true positives), we recruited another 2 women with normal screening results who were screened the same day at the same clinic. These participants were asked to complete the Consequences of Screening in Breast Cancer-a validated questionnaire encompassing 12 psychosocial outcomes-at baseline, 1, 6, 18, and 36 months.

RESULTS

Six months after final diagnosis, women with false-positive findings reported changes in existential values and inner calmness as great as those reported by women with a diagnosis of breast cancer (Δ = 1.15; P = .015; and Δ = 0.13; P = .423, respectively). Three years after being declared free of cancer, women with false-positive results consistently reported greater negative psychosocial consequences compared with women who had normal findings in all 12 psychosocial outcomes (Δ >0 for 12 of 12 outcomes; P <.01 for 4 of 12 outcomes).

CONCLUSION

False-positive findings on screening mammography causes long-term psychosocial harm: 3 years after a false-positive finding, women experience psychosocial consequences that range between those experienced by women with a normal mammogram and those with a diagnosis of breast cancer.

Mammographic density and risk of breast cancer according to tumor characteristics and mode of detection: a Spanish population-based case-control study

INTRODUCTION

It is not clear whether high mammographic density (MD) is equally associated with all subtypes of breast cancer (BC). We investigated the association between MD and subsequent BC, considering invasiveness, means of detection, pathologic subtype, and the time elapsed since mammographic exploration and BC diagnosis.

METHODS

BC cases occurring in the population of women who attended screening from 1997 through 2004 in Navarre, a Spanish region with a fully consolidated screening program, were identified via record linkage with the Navarre Cancer Registry (n = 1,172). Information was extracted from the records of their first attendance at screening in that period. For each case, we randomly selected four controls, matched by screening round, year of birth, and place of residence. Cases were classified according to invasiveness (ductal carcinoma in situ (DCIS) versus invasive tumors), pathologic subtype (considering hormonal receptors and HER2), and type of diagnosis (screen-detected versus interval cases). MD was evaluated by a single, experienced radiologist by using a semiquantitative scale. Data on BC risk factors were obtained by the screening program in the corresponding round. The association between MD and tumor subtype was assessed by using conditional logistic regression.

RESULTS

MD was clearly associated with subsequent BC. The odds ratio (OR) for the highest MD category (MD >75%) compared with the reference category (MD <10%) was similar for DCIS (OR = 3.47; 95% CI = 1.46 to 8.27) and invasive tumors (OR = 2.95; 95% CI = 2.01 to 4.35). The excess risk was particularly high for interval cases (OR = 7.72; 95% CI = 4.02 to 14.81) in comparison with screened detected tumors (OR = 2.17; 95% CI = 1.40 to 3.36). Sensitivity analyses excluding interval cases diagnosed in the first year after MD assessment or immediately after an early recall to screening yielded similar results. No differences were seen regarding pathologic subtypes. The excess risk associated with MD persisted for at least 7 to 8 years after mammographic exploration.

CONCLUSIONS

Our results confirm that MD is an important risk factor for all types of breast cancer. High breast density strongly increases the risk of developing an interval tumor, and this excess risk is not completely explained by a possible masking effect.

Seventeen-years overview of breast cancer inside and outside screening in Denmark

BACKGROUND

Long-term data on breast cancer detection in mammography screening programs are warranted to better understand the mechanisms by which screening changes the breast cancer pattern in the population. We aimed to analyze 17 years of breast cancer detection rates inside and outside screening in two Danish regions, emphasizing the influence of organizational differences of screening programs on the outcomes.

MATERIAL AND METHODS

We used data from two long-standing population-based mammography screening programs, Copenhagen and Fyn, in Denmark. Both programs offered biennial screening to women aged 50-69 years. We identified targeted, eligible, invited and participating women. We calculated screening detection and interval cancer rates for participants, and breast cancer incidence in non-screened women (= targeted women excluding participants) by biennial invitation rounds. Tumor characteristics were tabulated for each of the three groups of cancers.

RESULTS

Start of screening resulted in a prevalence peak in participants, followed by a decrease to a fairly stable detection rate in subsequent invitation rounds. A similar pattern was found for breast cancer incidence in non-screened women. In Fyn, non-screened women even had a higher rate than screening participants during the first three invitation rounds. The interval cancer rate was lower in Copenhagen than in Fyn, with an increase over time in Copenhagen, but not in Fyn. Screen-detected cancers showed tumor features related with a better prognosis than tumors detected otherwise, as more than 80% were smaller than 20 mm and estrogen receptor positive.

CONCLUSION

Data from two long-standing population-based screening programs in Denmark illustrated that even if background breast cancer incidence and organization were rather similar, performance indicators of screening could be strongly influenced by inclusion criteria and participation rates. Detection rates should be interpreted with caution as they may be biased by selection into the screening population.

Breast cancer detection risk in screening mammography after a false-positive result

BACKGROUND

False-positives are a major concern in breast cancer screening. However, false-positives have been little evaluated as a prognostic factor for cancer detection. Our aim was to evaluate the association of false-positive results with the cancer detection risk in subsequent screening participations over a 17-year period.

METHODS

This is a retrospective cohort study of 762,506 women aged 45-69 years, with at least two screening participations, who underwent 2,594,146 screening mammograms from 1990 to 2006. Multilevel discrete-time hazard models were used to estimate the adjusted odds ratios (OR) of breast cancer detection in subsequent screening participations in women with false-positive results.

RESULTS

False-positives involving a fine-needle aspiration cytology or a biopsy had a higher cancer detection risk than those involving additional imaging procedures alone (OR = 2.69; 95%CI: 2.28-3.16 and OR = 1.81; 95%CI: 1.70-1.94, respectively). The risk of cancer detection increased substantially if women with cytology or biopsy had a familial history of breast cancer (OR = 4.64; 95%CI: 3.23-6.66). Other factors associated with an increased cancer detection risk were age 65-69 years (OR = 1.84; 95%CI: 1.67-2.03), non-attendance at the previous screening invitation (OR = 1.26; 95%CI: 1.11-1.43), and having undergone a previous benign biopsy outside the screening program (OR = 1.24; 95%CI: 1.13-1.35).

CONCLUSION

Women with a false-positive test have an increased risk of cancer detection in subsequent screening participations, especially those with a false-positive result involving cytology or biopsy. Understanding the factors behind this association could provide valuable information to increase the effectiveness of breast cancer screening.

Breast cancer: missed interval and screening-detected cancer at full-field digital mammography and screen-film mammography-- results from a retrospective review

PURPOSE

To compare the percentages and mammographic features of cancers missed at full-field digital mammography (FFDM) and screen-film mammography (SFM) in women who participated in the Norwegian Breast Cancer Screening Program in 2002-2008.

MATERIALS AND METHODS

Social Science Data Services approval was obtained; the requirement for informed consent was waived. Cases were all the interval and screening-detected cancers from 35&emsp14;127 FFDM and 52&emsp14;444 SFM examinations in two Norwegian counties. Prior and diagnostic FFDM examinations of 49 interval and 86 screening-detected breast cancers were reviewed by four breast radiologists and compared with a review of SFM examinations of 81 interval and 123 screening-detected cancers. Cancers were classified as missed or true, mammographic features were described, percentages were compared by using the χ(2) or Fisher exact test, and 95% confidence intervals (CIs) were calculated.

RESULTS

The percentages of interval and screening-detected cancers missed at FFDM and SFM did not differ significantly. (interval cancers missed: 33% [16 of 49] at FFDM vs 30% [24 of 81] at SFM [P = .868]; screening-detected cancers missed: 20% [17 of 86] at FFDM vs 21% [26 of 123] at SFM [P = .946]). Asymmetry was present in 27% (95% CI: 13.3%, 45.5%) of prior mammograms of cancers missed at FFDM and 10% (95% CI: 3.3%, 21.8%) of those missed at SFM (P = .070). Calcifications were observed in 18% (95% CI: 7.0%, 35.5%) of the cancers missed at FFDM and 34% (95% CI: 21.2%, 48.8%) of those missed at SFM (P = .185). Average mammographic tumor size of missed cancers manifesting as masses was 10.4 mm at FFDM and 13.6 mm at SFM (P = .036).

CONCLUSION

The use of FFDM has not reduced the challenge of missed cancers. Cancers missed at FFDM tend to have different mammographic features than those missed at SFM.

Breast cancer mortality in Norway after the introduction of mammography screening

An organized mammography screening program was gradually implemented in Norway during the period 1996-2004. Norwegian authorities have initiated an evaluation of the program. Our study focused on breast cancer mortality. Using Poisson regression, we compared the change in breast cancer mortality from before to during screening in four counties starting the program early controlling for change in breast cancer mortality during the same time in counties starting the program late. A follow-up model included death in all breast cancers diagnosed during the follow-up period. An evaluation model included only breast cancers diagnosed in ages where screening was offered. The study group had been invited for screening one to three times and followed for on average of 5.9 years. In the follow-up model, 314 breast cancer deaths were observed in the study group, and 523, 404 and 638, respectively, in the four control groups. The ratio between the changes in breast cancer mortality between early and late starting counties was 0.93 (95% confidence interval [CI] 0.77-1.12). In the evaluation model, this ratio was 0.89 (95% CI: 0.71-1.12). In Norway, where 40% of women used regular mammography prior to the program, the implementation of the organized mammography screening program was associated with a statistically nonsignificant decrease in breast cancer mortality of around 11%.

Survival of women with breast cancer in central and northern Denmark, 1998-2009

Objective

Breast cancer is the most common cancer among women worldwide. The Nordic countries have relatively high survival, but Denmark has a lower survival than neighboring countries. A breast cancer screening program was introduced in 2007 and 2008 in the northern and central regions of Denmark respectively. We aimed to examine possible changes in survival of Danish breast cancer patients in central and northern Denmark in the period 1998–2009.

Materials and methods

From the northern and central Denmark regions, we included all women (n = 13,756) with an incident diagnosis of breast cancer, as recorded in the Danish National Registry of Patients during the period January 1, 1998 through December 31, 2009. We calculated age-stratified survival and used Cox proportional hazard regression to estimate mortality rate ratios (MRRs) for all breast cancer patients.

Results

Median age was 62 years (21–102 years). The overall 1-year survival improved steadily over the period from 90.9% in 1998–2000 to 94.4% in 2007–2009, corresponding to a 1-year age adjusted MRR of 0.68 in 2007–2009 compared with the reference period 1998–2000. We estimated the 5-year survival to improve from 70.0% in 1998–2000 to 74.7% in 2007–2009, corresponding to a 5-year age adjusted MRR of 0.82 in 2007–2009 compared with the reference period 1998–2000. For middle-aged women (50–74 years) 1-year survival increased from 92.8% in 1998–2000 to 96.6% in 2008–2009, and 5-year survival was expected to increase from 73.9% in 1998–2000 to 80.2% in 2007–2009. Among younger women (15–49 years) and elderly women (>75 years), 1-year survival and 5-year predicted survival did not change over the two time periods.

Conclusion

Survival of breast cancer patients has improved in Denmark over the period 1998–2009, and this change was most distinct in women aged 50–74 years. Survival improved even before the implementation of a formal breast cancer screening program.