Background No evidence-based guidelines regarding optimal breast compression in mammography exist, neither for standard digital mammography nor for digital breast tomosynthesis. Purpose To compare breast compression parameters and mean glandular dose in a randomized controlled trial with digital mammography versus digital breast tomosynthesis. Material and Methods We used information from 21,729 women aged 50–69 years, who participated in the To-Be trial, as part of BreastScreen Norway, 2016–2017. Information was obtained from the DICOM header and by assessing the images in an automated software for density estimation (VolparaDensity). Using linear regression, we investigated the effect of screening technique on breast compression parameters; compression force (N), compression pressure (kPa), and compressed breast thickness (mm), and mean glandular dose (mGy), by view (craniocaudal [CC] and mediolateral oblique [MLO]). We adjusted for age, breast volume and fibroglandular volume. Results A total of 11,056 (50.9%) women were screened with digital mammography and 10,673 (49.1%) with digital breast tomosynthesis. Adjusted regression analysis showed that women undergoing digital mammography received higher compression forces than women undergoing digital breast tomosynthesis (CC: –4.7 N; MLO: –1.1 N, P < 0.001 for both), higher compression pressure (CC: –1.0 k Pa; MLO: –0.1 kPa, P < 0.001 for both), and higher values of compressed breast thickness in the MLO view (–0.3 mm, P = 0.02). The women undergoing digital mammography received a lower mean glandular dose than women undergoing digital breast tomosynthesis ([+]0.06 mGy, P < 0.001). Conclusion Women undergoing digital breast tomosynthesis received lower compression force, compression pressure, and compressed breast thickness in MLO view, compared to women undergoing digital mammography. Further studies should investigate the impact of breast compression on image quality, screening outcome, and radiation dose for digital mammography and digital breast tomosynthesis in order to establish evidence-based guidelines for breast compression.

24.02.2020: Originalartikkel - Kvinner med kosmetiske brystimplantater som deltok i Mammografiprogrammet hadde lavere risiko for å få påvist brystkreft, men sykdommen ble oppdaget i et senere utviklingsstadium hos dem med implantat enn dem uten.

Objective:To compare breast characteristics, compression parameters, and early performance measures (rates of recall, screen-detected and interval breast cancer, and histopathologic tumour characteristics) for mammographic screening at a stationary versus mobile screening unit.Methods:Results from 92,408 mammographic screening examinations performed as part of BreastScreen Norway during 2008–2017 at either a stationary (n = 52,620) or mobile (n = 39,788) unit in Hordaland county were compared using descriptive statistics and generalized estimating equations. A generalized estimating equation for a binary outcome was used to estimate crude and adjusted odds ratios with 95% confidence intervals for the outcomes of interest. Adjusted generalized estimating equation models included age, breast volume, and density grade as covariates.Results:Screening at the stationary unit was performed on smaller breasts with higher mammographic density, using lower compression force but higher pressure than at the mobile unit. Using the stationary screening unit as reference, for women screened at the mobile unit, the adjusted odds ratio was: for recall 0.94 (95% CI: 0.87--1.01), screen-detected breast cancer 0.92 (95% CI: 0.78--1.10), and interval breast cancer 1.17 (95% CI: 0.83–1.64).Conclusions:The quality of care did not differ for women screened at the stationary versus the mobile unit, but there were differences between the women who attended the two units. Sociodemographic factors should be included in future analyses to fully understand the risk of breast cancer among women residing in urban versus rural areas.

Introduction: We aimed to investigate the association between breast compression and experienced pain during mammographic screening. Methods: Using a questionnaire, we collected information on pain experienced during mammography from 1155 women screened in Akershus, February-March 2018, as a part of BreastScreen Norway. The questionnaire provided information on pain using a numeric rating scale (NRS, 0-10) and related factors. Data on compression force (Newton, N), pressure (kilopascal, kPa) and breast characteristics were extracted from the DICOM-header and a breast density software. Log-binomial regression was used to determine the relative risk (RR) of severe versus mild/moderate experienced pain associated with compression parameters, adjusting for breast characteristics and related factors. Results: Mean score of experienced pain was 2.2, whereas 6% of the women reported severe pain (>= 7) during the examination. High body mass index (BMI) (>= 27.3 kg/m(2)) was associated with a higher RR of pain scores >= 7 (RR 1.86, 95%CI 1.02-3.36) compared to medium BMI (23.7-27.2 kg/m(2)). Low compression pressure (4.0-10.2 kPa) was associated with a higher RR of severe pain (RR 2.93, 95%CI 1.39 -6.20), compared with medium compression pressure (10.3-13.5 kPa) after adjusting for contact area, age, compressed breast thickness, volumetric breast density and BMI. The risk of severe versus mild/moderate pain (>= 7 versus <7) decreased by 2% with increasing compression force (RR 0.98, 95%CI 0.97 -1.00). Conclusion: Women reported low levels of pain during mammography. Further knowledge about factors affecting experienced pain is needed to personalize the examination to the individual woman. Implications for practice: Pain in shoulder(s) and/or neck prior to screening should be considered by the radiographers in a practical screening setting. A compression force of 100-140 N and pressure of 10.3 -13.5 kPa are acceptable with respect to reported pain during mammography. (c) 2019 The College of Radiographers. Published by Elsevier Ltd. All rights reserved.

Women with implants who participated in BreastScreen Norway had a lower risk of detection of breast cancer, but more advanced disease upon diagnosis than those without implants. This may be due to the difficulty caused by implants in performing and interpreting the mammograms. The women should be informed about this before undergoing augmentation mammoplasty.

To retrospectively investigate early performance measures of digital breast tomosynthesis (DBT) versus standard digital mammography (DM) for consecutive screening rounds. We included information about 35,736 women screened in BreastScreen Norway, 2008–2016, with at least two consecutive screening examinations. The pair of two consecutive screening examinations was the unit of analysis, and results from the subsequent examination were the measure of interest. Screening technique changed during the study period, resulting in four study groups: DM after DM, DBT after DM, DM after DBT, and DBT after DBT. We compared selected early performance measures between the study groups. Recall for DM after DM was 3.6% and lower for all other study groups (p < 0.001). The rate of screen-detected breast cancer was 4.6/1000 for DM after DM; for DBT after DM and DBT after DBT, it was 9.9/1000 and 8.3/1000, respectively (p < 0.001 relative to DM after DM), and for DM after DBT 4.3/1000. The rate of tubular carcinoma was higher for DBT after DBT or after DM compared with DM after DM (p < 0.01). The rate of histologic grade 1 tumors was higher for DBT after DM compared with DM after DM (p < 0.001). We did not observe any statistical difference in the interval cancer rates. Lower recall and higher cancer detection rates for screening with DBT were sustainable over two consecutive screening rounds. Positive predictive values were higher for DBT than DM. There were no differences in the interval cancer rates between the study groups. • There is limited knowledge about early performance measures for screening with digital breast tomosynthesis beyond one screening round. • A decline in recall rate and an incline in the rate of screen-detected breast cancer were observed for women screened with DBT compared with DM, irrespective of prior screening technique. The interval breast cancer rate did not differ statistically for women screened with DBT versus DM. • Tumor characteristics tended to be prognostic favorable for DBT compared with DM with no differences in rates of more advanced cancers. The clinical significance of increased cancer detection and the potential for future mortality reduction remain unknown.

Objectives: We aimed to compare pain experienced during screening mammography, using three different compression paddles: a fixed paddle standardizing pressure (study paddle), a flexible, and a fixed paddle. Material and methods: Using a numeric rating scale (NRS), ranged 0-10, we collected information on pain experienced during mammography from a questionnaire completed by 4,675 women screened in Stavanger, May-November 2017, as a part of BreastScreen Norway. The questionnaire also provided information on factors possibly associated with pain. Data on compression force, pressure and breast characteristics were extracted from the DICOM-header, and a breast density software. T-tests were used to compare mean values of the parameters between the types of compression paddles. Linear regression was used to determine the association of a score of >= 7 versus < 7 on NRS for experienced pain by compression paddle, adjusting for pressure, breast characteristics and associated factors. Results: The mean of experienced pain did not differ for the study and flexible paddle (2.5 on NRS), and was lower for the study paddle compared to the fixed paddle (2.4 versus 2.6 on NRS, p < 0.05). Pain in shoulder(s) and/or neck prior to mammography was associated with 33% (RR 1.33, 95% CI 1.07-1.65) higher risk of a score of >= 7 versus < 7 for experienced pain. Conclusion: The majority of women reported low scores of experienced pain during mammography, independent of compression paddle used. Further research on image quality is needed to fully understand which paddles should be preferred in a screening setting.

Background Digital breast tomosynthesis (DBT) is replacing digital mammography (DM) in the clinical workflow. Currently, there are limited prospective studies comparing the diagnostic accuracy of both examinations and the role of synthetic mammography (SM) and computer-aided detection (CAD). Purpose To compare the accuracy of DM versus DM + DBT in population-based breast cancer screening. Materials and Methods This prospective study, performed from November 2010 to December 2012, included 24 301 women (mean age, 59.1 years ± 5.7 [standard deviation]) with 281 cancers, of which 51 were interval cancers. Each examination was independently interpreted with four reading modes: DM, DM + CAD, DM + DBT, and SM + DBT. Sensitivity and specificity were compared for DM versus DM + DBT, DM versus DM + CAD, DM + DBT versus SM + DBT, and DM versus DM + DBT at double reading. Reader-adjusted performance characteristics of reading modes were evaluated on the basis of pre-arbitration (initial interpretation) scores. Statistical analysis was based on cluster bootstrap analysis using 10 000 random resamples. Results Sensitivity was 54.1% (152 of 281) for DM and 70.5% (198 of 281) for DM + DBT. Reader-adjusted difference was 12.6% (95% confidence interval [CI]: 5.2%, 19.7%; P = .001). Specificity was 94.2% (false-positive fraction [FPF], 5.8%; 1388 of 24 020) for DM and 95.0% (FPF, 5.0%; 1209/24 020) for DM + DBT, with a reader-adjusted difference in FPF of -1.2% (95% CI: -1.7%, -0.7%; P < .001). Sensitivity was 69.0% (194 of 281) for SM + DBT and 70.5% (198 of 281) for DM + DBT, with a reader-adjusted difference of 1.0% (95% CI: -6.2%, 8.5%; P = .77). Specificity was 95.4% (FPF, 4.6%; 1111 of 24 020) for SM + DBT and 95.0% (FPF, 5.0%;1209 of 24 020) for DM + DBT, with reader-adjusted 95% CIs for FPF of 4.7%, 5.4% and 5.0%, 5.7%, respectively, and a difference of -0.3% (95% CI: -0.8%, 0.2%; P = .23). Differences in sensitivity and specificity with the addition of CAD were small and not significant (P > .2). Conclusion Addition of digital breast tomosynthesis to digital mammography resulted in significant gains in sensitivity and specificity. Synthetic mammography in combination with digital breast tomosynthesis had similar sensitivity and specificity to digital mammography in combination with digital breast tomosynthesis. © RSNA, 2019 See also the editorial by Lång in this issue.

Background Digital breast tomosynthesis is an advancement of mammography, and has the potential to overcome limitations of standard digital mammography. This study aimed to compare first-generation digital breast tomosynthesis including two-dimensional (2D) synthetic mammograms versus digital mammography in a population-based screening programme. Methods BreastScreen Norway offers all women aged 50-69 years two-view (craniocaudal and mediolateral oblique) mammographic screening every 2 years and does independent double reading with consensus. We asked all 32 976 women who attended the programme in Bergen in 2016-17, to participate in this randomised, controlled trial with a parallel group design. A study-specific software was developed to allocate women to either digital breast tomosynthesis or digital mammography using a 1:1 simple randomisation method based on participants' unique national identity numbers. The interviewing radiographer did the randomisation by entering the number into the software. Randomisation was done after consent and was therefore concealed from both the women and the radiographer at the time of consent; the algorithm was not disclosed to radiographers during the recruitment period. All data needed for analyses were complete 12 months after the recruitment period ended. The primary outcome measure was screen-detected breast cancer, stratified by screening technique (ie, digital breast tomosynthesis and digital mammography). A log-binomial regression model was used to estimate the efficacy of digital breast tomosynthesis versus digital mammography, defined as the crude risk ratios (RRs) with 95% CIs for screen-detected breast cancer for women screened during the recruitment period. A per-protocol approach was used in the analyses. This trial is registered at ClinicalTrials.gov, number NCT02835625, and is closed to accrual. Findings Between, Jan 14, 2016, and Dec 31, 2017, 44 266 women were invited to the screening programme in Bergen, and 32976 (74.5%) attended. After excluding women with breast implants and women who did not consent to participate, 29 453 (89.3%) were eligible for electronic randomisation. 14734 women were allocated to digital breast tomosynthesis and 14719 to digital mammography. After randomisation, women with a previous breast cancer were excluded (digital breast tomosynthesis group n=314, digital mammography group n=316), women with metastases from melanoma (digital breast tomosynthesis group n=1), and women 1who informed the radiographer about breast symptoms after providing consent (digital breast tomosynthesis group n=39, digital mammography group n=34). After exclusions, information from 28749 women were included in the analyses (digital breast tomosynthesis group n=14380, digital mammography group n=14369). The proportion of screen-detected breast cancer among the screened women did not differ between the two groups (95 [0.66%, 0.53-0.79] of 14380 vs 87 [0.61%, 0.48-0.73] of 14369; RR 1.09, 95% CI 0.82-1-46; p=0.56). Interpretation This study indicated that digital breast tomosynthesis including synthetic 2D mammograms was not significantly different from standard digital mammography as a screening tool for the detection of breast cancer in a population-based screening programme. Economic analyses and follow-up studies on interval and consecutive round screen-detected breast cancers are needed to better understand the effect of digital breast tomosynthesis in population-based breast cancer screening. Copyright (C) 2019 Elsevier Ltd. All rights reserved.

Background: We estimated breast cancer (BC) mortality reduction associated with invitations to a nationwide population-based screening program and with changes in treatment. Materials and methods: BreastScreen Norway started in 1996 and became nationwide in 2005. It invites women aged 50-69 years to biennial mammographic screening. We retrieved individual-level data for 1 340 333 women from national registries. During 1996-2014 (screening window), women contributed person-years in noninvited and invited periods. We created comparable periods for 1977-1995 (prescreening window) by dividing the follow-up time for each woman into pseudo-noninvited and pseudo-invited periods. We estimated BC mortality for the four periods, using the so-called evaluation model: counting BC deaths in each period for all women diagnosed within the period and counting BC deaths and person-years after screening-age for those diagnosed within screening age. We used a multivariable flexible parametric survival model to estimate hazard ratio (HR) for the effect of invitation and improved treatment. Results: Using the regression approach, we found 5818 BC deaths across 16 533 281 person-years. Invitations to screening reduced BC mortality by 20% (HR = 0.80, 95% confidence interval [CI] = 0.70 to 0.91) among women 50 years and older and by 25% (HR = 0.75, 95% CI = 0.65 to 0.86) among screening-aged women. The treatment effect was 23% (HR = 0.77, 95% CI = 0.65 to 0.92) for women 50 years and older and 17% (HR = 0.83, 95% CI = 0.74 to 0.94) for screening-aged women. Conclusion: We observed a similar reduction in BC mortality associated with invitations to screening and improvements in treatment during 1977-2014, among women 50 years and older.

Aims: Risk factors for breast cancer are often used for adjustment in epidemiological studies, including in the evaluation of early performance measures in mammographic screening. Information about risk factors among participants in the Norwegian Breast Cancer Screening Program has been collected since 2006. We aimed to examine the validity of self-reported history of breast cancer and mammographic screening, as well as the reliability of weight and height amongt women attending the program. Methods: Information from a questionnaire handed in by participants in the program, 2006–2015, was linked to outcomes from the Cancer Registry of Norway. Sensitivity, specificity, and positive predictive values (PPV) were calculated for self-reported histories of breast cancer and screening. Results were stratified by five-year age groups and evaluated using the χ2 statistic. The reliability of self-reported weight and height were assessed using descriptive statistics, histograms, and mean differences. Results: A total of 538,907 of 611,711 (88%) women attending the program during the study period returned at least one part of the questionnaire. The overall sensitivity, specificity, and PPV for breast cancer and mammography were 96.5%, 99.8%, and 81.3%; and 99.9%, 84.4%, and 97.6% respectively. The mean difference in self-reported weight was 0.35 kg and for height was −0.14 cm, over a period of up to 10 years. Conclusions: Norwegian women attending the screening program are reasonably accurate in self-reporting their breast cancer and mammography histories. On average, women consistently reported weight and height within one kg/cm.

Background We analyzed the consistency in absolute and percent density using an automated method for estimating volumetric breast density among women who attended BreastScreen Norway 2007-2015. Material and Methods We used information from 33,711 women aged 50-69 who underwent two to five full field digital screening examinations biennially, 2007-2015. BMI and HT-use was obtained from a self-administered questionnaire, sent together with the invitation to screening. BMI was categorized into <21.0; 21.0-24.9; ≥25.0 kg/m2, while use of HT was defined as ever versus never used. An automated method estimated fibroglandular volume (cm3), breast volume (cm3) and volumetric breast density (%) for each screening examination. We applied mixed-effects linear models to estimate associations between age, fibroglandular volume, breast volume and volumetric breast density over time including data on BMI and HT. Results The results models indicated age to be associated with decreased fibroglandular volume and volumetric breast density, and increased breast volume. BMI <21 kg/m2 was associated with higher volumetric breast density, but lower fibroglandular and breast volume. Contrary, BMI ≥25 kg/m2 was associated with lower volumetric breast density and higher fibroglandular and breast volumes. Variation in volumetric breast density and fibroglandular volume within women was rather subtle: this variance did not exceed 10% for either volumetric breast density, fibroglandular volume or breast volume. Conclusion Automated measures of volumetric breast density and fibroglandular volume software decreased with age among women screened in BreastScreen Norway. Absolute and percent density varied with a maximum of 10% over time, from first to last screening examination.

Background Breast compression is used in mammography to improve image quality and reduce radiation dose. However, the compression may lead to discomfort or pain for the women. Breast compression time is longer with digital breast tomosynthesis (DBT) than with digital mammography (DM). We aimed to explore breast compression parameters with DM and DBT. Material and Methods We used information from 16,832 women participating in the Tomosynthesis Trial in Bergen between January 2016 and April 2017. We compared mean values of applied compression force (N), compression pressure (kPa) and compressed breast thickness (mm) for DM and DBT, by view (craniocaudal, CC, and mediolateral-oblique, MLO). Two-sample t-tests were used to test statistical significance. Results Number of women screened with DM or DBT were similar (DM: n = 8354 and DBT: n = 8478). Mean compression force was statistically significantly higher for DM compared to DBT (CC: 108.6 N versus 102.7 N; MLO: 122.4 N versus 120.8 N, p < 0.01). Mean compression pressure was higher for DM compared to DBT for CC view (13.9 kPa versus 13.0 kPa, p < 0.01), however, not for MLO view (DM and DBT: 9.7 kPa, p = 0.55). Mean compressed breast thickness did not differ statistically significantly for DM compared to DBT (CC: 58.7 mm N versus 58.6 mm, p = 0.72; MLO: 60.1 mm versus 59.9 mm, p = 0.23). Conclusion Radiographers applied less breast compression with DBT compared to DM. However, the observed differences were negligible. Further research should investigate the clinical implications of the differences, such as image quality.

Adherence to screening may indirectly help assess whether a prior screening examination deters women from returning for a subsequent examination. We investigated whether compression force and pressure in mammography were associated with re-attendance among prevalently screened women in the organized breast cancer screening program in Norway. Data on compression force (kg) and pressure (kPa) from women's first screening examination in the program (prevalent screening) and subsequent re-attendance were available for 31,225 women aged 50-68, screened during 2007-2013. Crude re-attendance rates and log-binomial regression models estimating the prevalence ratio of re-attendance were used to identify the association between compression force or pressure and re-attendance two-years later. Age and year at prevalent screening, county of residence, screening result (negative or false positive), breast volume, and breast density were included in analyses. Overall, 27,197 (87.1%) women re-attended the program. Re-attendance was highest for women who received a compression force of 10.0-13.9 kg (87.5%) or pressure of 9.0-17.9 kPa (87.8%) and lowest for those who received a compression force of < 10.0 kg (85.0%) or pressure of < 9.0 kPa (84.7%). The adjusted prevalence of re-attendance was 3% lower for women who received low compression force (< 10.0 kg) and 2% lower for women who received low compression pressure (< 9.0 kPa) relative to the reference groups (10.0-13.9 kg and 9.0-17.9 kPa, respectively). Future research related to re-attendance should also include information about women's experience of pain, anxiety and stress, as well as image quality.

This study proposes a method to optimize the performance of BreastScreen Norway through a stratified recommendation of tests including independent double or single reading of the screening mammograms and additional imaging with or without core needle biopsy. This is carefully evaluated by a value of information analysis. An estimated graphical probabilistic model describing the relationship between a set of risk factors and the corresponding risk of breast cancer is used for this analysis, together with a Bayesian network modeling screening test results conditional on the true (but unknown) breast cancer status of a woman. This study contributes towards evaluating a possibility of improving the efficiency of the screening program, where all women aged 50 to 69 are invited every second year, regardless of individual risk factors. Our stratified recommendation of tests is dependent on the probability that an asymptomatic woman has developed breast cancer at the time she is invited to a screening.