Women's attitudes and perspectives on the use of artificial intelligence in the assessment of screening mammograms.

PURPOSE: To investigate attitudes and perspectives on the use of artificial intelligence (AI) in the assessment of screening mammograms among women invited to BreastScreen Norway. METHOD: An anonymous survey was sent to all women invited to BreastScreen Norway during the study period, October 10, 2022, to December 25, 2022 (n = 84,543). Questions were answered on a 10-point Likert scale and as multiple-choice, addressing knowledge of AI, willingness to participate in AI studies, information needs, confidence in AI results and AI assisted reading strategies, and thoughts on concerns and benefits of AI in mammography screening. Analyses were performed using χ2 and logistic regression tests. RESULTS: General knowledge of AI was reported as extensive by 11.0% of the 8,355 respondents. Respondents were willing to participate in studies using AI either for decision support (64.0%) or triaging (54.9%). Being informed about use of AI-assisted image assessment was considered important, and a reading strategy of AI in combination with one radiologist preferred. Having extensive knowledge of AI was associated with willingness to participate in AI studies (decision support; odds ratio [OR]: 5.1, 95% confidence interval [CI]: 4.1-6.4, and triaging; OR: 3.4, 95% CI: 2.8-4.0) and trust in AI's independent assessment (OR: 6.8, 95% CI: 5.7, 8.3). CONCLUSIONS: Women invited to BreastScreen Norway had a positive attitude towards the use of AI in image assessment, given that human readers are still involved. Targeted information and increased public knowledge of AI could help achieve high participation in AI studies and successful implementation of AI in mammography screening.

AI performance by mammographic density in a retrospective cohort study of 99,489 participants in BreastScreen Norway.

OBJECTIVE: To explore the ability of artificial intelligence (AI) to classify breast cancer by mammographic density in an organized screening program. MATERIALS AND METHOD: We included information about 99,489 examinations from 74,941 women who participated in BreastScreen Norway, 2013-2019. All examinations were analyzed with an AI system that assigned a malignancy risk score (AI score) from 1 (lowest) to 10 (highest) for each examination. Mammographic density was classified into Volpara density grade (VDG), VDG1-4; VDG1 indicated fatty and VDG4 extremely dense breasts. Screen-detected and interval cancers with an AI score of 1-10 were stratified by VDG. RESULTS: We found 10,406 (10.5% of the total) examinations to have an AI risk score of 10, of which 6.7% (704/10,406) was breast cancer. The cancers represented 89.7% (617/688) of the screen-detected and 44.6% (87/195) of the interval cancers. 20.3% (20,178/99,489) of the examinations were classified as VDG1 and 6.1% (6047/99,489) as VDG4. For screen-detected cancers, 84.0% (68/81, 95% CI, 74.1-91.2) had an AI score of 10 for VDG1, 88.9% (328/369, 95% CI, 85.2-91.9) for VDG2, 92.5% (185/200, 95% CI, 87.9-95.7) for VDG3, and 94.7% (36/38, 95% CI, 82.3-99.4) for VDG4. For interval cancers, the percentages with an AI score of 10 were 33.3% (3/9, 95% CI, 7.5-70.1) for VDG1 and 48.0% (12/25, 95% CI, 27.8-68.7) for VDG4. CONCLUSION: The tested AI system performed well according to cancer detection across all density categories, especially for extremely dense breasts. The highest proportion of screen-detected cancers with an AI score of 10 was observed for women classified as VDG4. CLINICAL RELEVANCE STATEMENT: Our study demonstrates that AI can correctly classify the majority of screen-detected and about half of the interval breast cancers, regardless of breast density. KEY POINTS: • Mammographic density is important to consider in the evaluation of artificial intelligence in mammographic screening. • Given a threshold representing about 10% of those with the highest malignancy risk score by an AI system, we found an increasing percentage of cancers with increasing mammographic density. • Artificial intelligence risk score and mammographic density combined may help triage examinations to reduce workload for radiologists.

Digital breast tomosynthesis in mammographic screening: false negative cancer cases in the To-Be 1 trial.

OBJECTIVES: The randomized controlled trial comparing digital breast tomosynthesis and synthetic 2D mammograms (DBT + SM) versus digital mammography (DM) (the To-Be 1 trial), 2016-2017, did not result in higher cancer detection for DBT + SM. We aimed to determine if negative cases prior to interval and consecutive screen-detected cancers from DBT + SM were due to interpretive error. METHODS: Five external breast radiologists performed the individual blinded review of 239 screening examinations (90 true negative, 39 false positive, 19 prior to interval cancer, and 91 prior to consecutive screen-detected cancer) and the informed consensus review of examinations prior to interval and screen-detected cancers (n = 110). The reviewers marked suspicious findings with a score of 1-5 (probability of malignancy). A case was false negative if ≥ 2 radiologists assigned the cancer site with a score of ≥ 2 in the blinded review and if the case was assigned as false negative by a consensus in the informed review. RESULTS: In the informed review, 5.3% of examinations prior to interval cancer and 18.7% prior to consecutive round screen-detected cancer were considered false negative. In the blinded review, 10.6% of examinations prior to interval cancer and 42.9% prior to consecutive round screen-detected cancer were scored ≥ 2. A score of ≥ 2 was assigned to 47.8% of negative and 89.7% of false positive examinations. CONCLUSIONS: The false negative rates were consistent with those of prior DM reviews, indicating that the lack of higher cancer detection for DBT + SM versus DM in the To-Be 1 trial is complex and not due to interpretive error alone. CRITICAL RELEVANCE STATEMENT: The randomized controlled trial on digital breast tomosynthesis and synthetic 2D mammograms (DBT) and digital mammography (DM), 2016-2017, showed no difference in cancer detection for the two techniques. The rates of false negative screening examinations prior to interval and consecutive screen-detected cancer for DBT were consistent with the rates in prior DM reviews, indicating that the non-superior DBT performance in the trial might not be due to interpretive error alone. KEY POINTS: • Screening with digital breast tomosynthesis (DBT) did not result in a higher breast cancer detection rate compared to screening with digital mammography (DM) in the To-Be 1 trial. • The false negative rates for examinations prior to interval and consecutive screen-detected cancer for DBT were determined in the trial to test if the lack of differences was due to interpretive error. • The false negative rates were consistent with those of prior DM reviews, indicating that the lack of higher cancer detection for DBT versus DM was complex and not due to interpretive error alone.

Mammographic features and risk of breast cancer death among women with invasive screen-detected cancer in BreastScreen Norway 1996-2020.

OBJECTIVES: We explored associations between mammographic features and risk of breast cancer death among women with small (<15 mm) and large (≥15 mm) invasive screen-detected breast cancer. METHODS: We included data from 17,614 women diagnosed with invasive breast cancer as a result of participation in BreastScreen Norway, 1996-2020. Data on mammographic features (mass, spiculated mass, architectural distortion, asymmetric density, density with calcification and calcification alone), tumour diameter and cause of death was obtained from the Cancer Registry of Norway. Cox regression was used to estimate hazard ratios (HR) with 95% confidence intervals (CI) for breast cancer death by mammographic features using spiculated mass as reference, adjusting for age, tumour diameter and lymph node status. All analyses were dichotomised by tumour diameter (small versus large). RESULTS: Mean age at diagnosis was 60.8 (standard deviation, SD=5.8) for 10,160 women with small tumours and 60.0 (SD=5.8) years for 7454 women with large tumours. The number of breast cancer deaths was 299 and 634, respectively. Mean time from diagnosis to death was 8.7 (SD=5.0) years for women with small tumours and 7.2 (4.6) years for women with large tumours. Using spiculated mass as reference, adjusted HR for breast cancer death among women with small tumours was 2.48 (95% CI 1.67-3.68) for calcification alone, while HR for women with large tumours was 1.30 (95% CI 1.02-1.66) for density with calcification. CONCLUSIONS: Small screen-detected invasive cancers presenting as calcification and large screen-detected cancers presenting as density with calcification were associated with the highest risk of breast cancer death. CLINICAL RELEVANCE STATEMENT: Small tumours (<15 mm) presented as calcification alone and large tumours (≥ 15 mm) presented as density with calcification were associated with the highest risk of breast cancer death among women with screen-detected invasive breast cancer diagnosed 1996-2020. KEY POINTS: • Women diagnosed with invasive screen-detected breast cancer 1996-2020 were analysed. • Small screen-detected cancers presenting as calcification alone resulted in the highest risk of breast cancer death. • Large screen-detected cancers presenting as density with calcification resulted in the highest risk of breast cancer death.

Personalized Breast Cancer Screening: A Risk Prediction Model Based on Women Attending BreastScreen Norway.

BACKGROUND: We aimed to develop and validate a model predicting breast cancer risk for women targeted by breast cancer screening. METHOD: This retrospective cohort study included 57,411 women screened at least once in BreastScreen Norway during the period from 2007 to 2019. The prediction model included information about age, mammographic density, family history of breast cancer, body mass index, age at menarche, alcohol consumption, exercise, pregnancy, hormone replacement therapy, and benign breast disease. We calculated a 4-year absolute breast cancer risk estimates for women and in risk groups by quartiles. The Bootstrap resampling method was used for internal validation of the model (E/O ratio). The area under the curve (AUC) was estimated with a 95% confidence interval (CI). RESULTS: The 4-year predicted risk of breast cancer ranged from 0.22-7.33%, while 95% of the population had a risk of 0.55-2.31%. The thresholds for the quartiles of the risk groups, with 25% of the population in each group, were 0.82%, 1.10%, and 1.47%. Overall, the model slightly overestimated the risk with an E/O ratio of 1.10 (95% CI: 1.09-1.11) and the AUC was 62.6% (95% CI: 60.5-65.0%). CONCLUSIONS: This 4-year risk prediction model showed differences in the risk of breast cancer, supporting personalized screening for breast cancer in women aged 50-69 years.

Early screening outcomes before, during, and after a randomized controlled trial with digital breast tomosynthesis.

PURPOSE: To describe and compare early screening outcomes before, during and after a randomized controlled trial with digital breast tomosynthesis (DBT) including synthetic 2D mammography versus standard digital mammography (DM) (To-Be 1) and a follow-up cohort study using DBT (To-Be 2). METHODS: Retrospective results of 125,020 screening examinations from four consecutive screening rounds performed in 2014-2021 were described and compared for pre-To-Be 1 (DM), To-Be 1 (DM or DBT), To-Be 2 (DBT), and post-To-Be 2 (DM) cohorts. Descriptive analyses of rates of recall, biopsy, screen-detected and interval cancer, distribution of histopathologic tumor characteristics and time spent on image interpretation and consensus were presented for the four rounds including five cohorts, one cohort in each screening round except for the To-Be 1 trail, which included a DBT and a DM cohort. Odds ratios (OR) with 95% CIs was calculated for recall and cancer detection rates. RESULTS: Rate of screen-detected cancer was 0.90% for women screened with DBT in To-Be 2 and 0.64% for DM in pre-To-Be 1. The rates did not differ for the To-Be 1 DM (0.61%), To-Be 1 DBT (0.66%) and post-To-Be 2 DM (0.67%) cohorts. The interval cancer rates ranged between 0.13% and 0.20%. The distribution of histopathologic tumor characteristics did not differ between the cohorts. CONCLUSIONS: Screening all women with DBT following a randomized controlled trial in an organized, population-based screening program showed a temporary increase in the rate of screen-detected cancer.

Quality of life among women with symptomatic, screen-detected, and interval breast cancer, and for women without breast cancer: a retrospective cross-sectional study from Norway.

PURPOSE: Breast cancers detected at screening need less aggressive treatment compared to breast cancers detected due to symptoms. The evidence on the quality of life associated with screen-detected versus symptomatic breast cancer is sparse. This study aimed to compare quality of life among Norwegian women with symptomatic, screen-detected and interval breast cancer, and women without breast cancer and investigate quality adjusted life years (QALYs) for women with breast cancer from the third to 14th year since diagnosis. METHODS: This retrospective cross-sectional study was focused on women aged 50 and older. A self-reported questionnaire including EQ-5D-5L was sent to 11,500 women. Multivariable median regression was used to analyze the association between quality of life score (visual analogue scale 0-100) and detection mode. Health utility values representing women's health status were extracted from EQ-5D-5L. QALYs were estimated by summing up the health utility values for women stratified by detection mode for each year between the third and the 14th year since breast cancer diagnosis, assuming that all women would survive. RESULTS: Adjusted regression analyses showed that women with screen-detected (n = 1206), interval cancer (n = 1005) and those without breast cancer (n = 1255) reported a higher median quality of life score using women with symptomatic cancer (n = 1021) as reference; 3.7 (95%CI 2.2-5.2), 2.3 (95%CI 0.7-3.8) and 4.8 (95%CI 3.3-6.4), respectively. Women with symptomatic, screen-detected and interval cancer would experience 9.5, 9.6 and 9.5 QALYs, respectively, between the third and the 14th year since diagnosis. CONCLUSION: Women with screen-detected or interval breast cancer reported better quality of life compared to women with symptomatic cancer. The findings add benefits of organized mammographic screening.

Comparability and validity of cancer registry data in the northwest of Russia.

BACKGROUND: Despite the elaborate history of statistical reporting in the USSR, Russia established modern population-based cancer registries (PBCR) only in the 1990s. The quality of PBCRs data has not been thoroughly analyzed. This study aims at assessing the comparability and validity of cancer statistics in regions of the Northwestern Federal District (NWFD) of Russia. MATERIAL AND METHODS: Data from ten Russian regional PBCRs covering ∼13 million (∼5 million in St. Petersburg) were processed in line with IARC/IACR and ENCR recommendations. We extracted and analyzed all registered cases but focused on cases diagnosed between 2008 and 2017. For comparability and validity assessment, we applied established qualitative and quantitative methods. RESULTS: Data collection in NWFD is in line with international standards. Distributions of diagnosis dates revealed higher variation in several regions, but overall, distributions are relatively uniform. The proportion of multiple primaries between 2008 and 2017 ranged from 6.7% in Vologda Oblast to 12.4% in Saint-Petersburg. We observed substantial regional heterogeneity for most indicators of validity. In 2013-2017, proportions of morphologically verified cases ranged between 61.7 and 89%. Death certificates only (DCO) cases proportion was in the range of 1-14% for all regions, except for Saint-Petersburg (up to 23%). The proportion of cases with a primary site unknown was between 1 and 3%. Certain cancer types (e.g., pancreas, liver, hematological malignancies, and CNS tumors) and cancers in older age groups showed lower validity. CONCLUSION: While the overall level of comparability and validity of PBCRs data of four out of ten regions of NWFD of Russia meets the international standards, differences between the regions are substantial. The local instructions for cancer registration need to be updated and implemented. The data validity assessment also reflects pitfalls in the quality of diagnosis of certain cancer types and patient groups.

History and current status of cancer registration in Russia.

BACKGROUND: Russia, then part of the Union of Soviet Socialist Republics (the USSR), introduced compulsory cancer registration in 1953, but a clear overall contemporary description of the cancer surveillance system in Russia is not available. METHODS: We summarized historical landmarks and the development of the standards of classification and coding of neoplasms in Russia and described current population-based cancer registries' (PBCR) procedures and practices. RESULTS: Cancer registration is organized according to the administrative division of the Russian Federation. More than 600,000 cases are registered annually. All medical facilities, without exception, are required to notify the PBCR about newly diagnosed cases, and each regional PBCR is responsible for registering all cancers diagnosed in citizens residing in the region. The data collection can be described as passive and exhaustive. Hematological malignancies, brain, and CNS tumors are often not referred to cancer hospitals in some regions, explaining the problems in registering these cancers. CONCLUSION: Russia's cancer registration system is population-based, and practices seem to be generally internationally comparable. However, coding practices and national guidelines are still outdated and not up to the most recent international recommendations. Further analyses are needed to assess the comparability, validity, completeness, and timeliness of Russia's PBCRs data.

Factors associated with attendance and attendance patterns in a population-based mammographic screening program.

OBJECTIVE: To explore the factors associated with attendance and attendance pattern in BreastScreen Norway. METHODS: We evaluated the number of invitations (n = 1,253,995) and attendances, 2015-2019, stratified by age, invitation method, screening unit and time of appointment. Attendance pattern was analysed for women invited 10 times (n = 47,979), 1996-2019. The association of education level, body mass index, physical activity and smoking status with attendance was analysed for a sub-sample of women (n = 37,930). Descriptive statistics were used to analyse attendance, and negative binomial regression was used to analyse the association between the total number of attendances and education level and lifestyle factors. RESULTS: The attendance rate was 76.0%, 2015-2019. The rate was 78.0% for women aged >64 and 73.9% for those <55 . We found a rate of 82.0% for women who received a digital invitation, while it was 73.7% for those invited by post. The rate was 78.1% for invitations in the late afternoon, 3-6 p.m., while later appointments reached a rate of 73.7%. Half of the women invited 10 times attended all times. The predicted total number of attendances was 9 out of 10 for the factors investigated. CONCLUSION: The highest attendance rates were shown for women aged >64, those who received digital invitations and those having appointments in late afternoon. The differences in predicted number of attendances between the investigated factors were minor. Overall, BreastScreen Norway has a high attendance rate. However, efforts aimed at increasing the attendance in specific groups should be considered.

Interval and Subsequent Round Breast Cancer in a Randomized Controlled Trial Comparing Digital Breast Tomosynthesis and Digital Mammography Screening.

Background Prevalent digital breast tomosynthesis (DBT) has shown higher cancer detection rates and lower recall rates compared with those of digital mammography (DM). However, data are limited on rates and histopathologic tumor characteristics of interval and subsequent round screen-detected cancers for DBT. Purpose To follow women randomized to screening with DBT or DM and to investigate rates and tumor characteristics of interval and subsequent round screen-detected cancers. Materials and Methods To-Be is a randomized controlled trial comparing the outcome of DBT and DM in organized breast cancer screening. The trial included 28 749 women, with 22 306 women returning for subsequent DBT screening 2 years later (11 201 and 11 105 originally screened with DBT and DM, respectively). Differences in rates, means, and distribution of histopathologic tumor characteristics between women prevalently screened with DBT versus DM were evaluated with Z tests, t tests, and χ2 tests. Relative risk (RR) with 95% CIs was calculated for the cancer rates. Results Interval cancer rates were 1.4 per 1000 screens (20 of 14 380; 95% CI: 0.9, 2.1) for DBT versus 2.0 per 1000 screens (29 of 14 369; 95% CI: 1.4, 2.9; P = .20) for DM. The rates of subsequent round screen-detected cancer were 8.1 per 1000 (95% CI: 6.6, 10.0) for women originally screened with DBT and 9.1 per 1000 (95% CI: 7.4, 11.0; P = .43) for women screened with DM. The distribution of tumor characteristics did not differ between groups for either interval or subsequent screen-detected cancer. The RR of interval cancer was 0.69 (95% CI: 0.39, 1.22; P = .20) for DBT versus DM, whereas RR of subsequent screen-detected cancer for women prevalently screened with DBT versus DM was 0.89 (95% CI: 0.67, 1.19; P = .43). Conclusion Rates of interval or subsequent round screen-detected cancers and their tumor characteristics did not differ between women originally screened with digital breast tomosynthesis (DBT) versus digital mammography. The analysis suggests that the benefits of prevalent DBT screening did not come at the expense of worse downstream screening performance measures in a population-based screening program. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Taourel in this issue.

Digital breast tomosynthesis in a population based mammographic screening program: Breast compression and early performance measures.

PURPOSE: We aimed to determine if compression force or pressure could be associated with early performance measures for women screened with digital breast tomosynthesis (DBT) in BreastScreen Norway. Early performance measures included rates of consensus, recall, and screen-detected breast cancer. METHOD: Data on compression force and pressure, compressed breast thickness and breast characteristics were extracted from an automated software for density assessment of DBT screening examinations for 25,286 women. For descriptive analyses, force (Newton, N) and pressure (kilopascal, kPa) were categorized into quartiles. Analyses were stratified by mammographic view, craniocaudal (CC) and mediolateral oblique (MLO). Logistic regression with restricted cubic splines was used to investigate the association between force and pressure as continuous exposures and early performance measures adjusted for age, compressed breast thickness and fibroglandular volume. RESULTS: Mean age of the screened women was 60.7 (SD = 5.2) years. Mean compression force was 90.8 (SD = 14.2) N for CC and 106.3 (SD = 20.6) N for MLO, and pressure was 11.3 (SD = 3.6) kPa for CC and 8.7 (SD = 2.0) kPa for MLO. The highest rates of screen-detected cancer were observed for low force (1.04 % for <82.5 N for CC and 1.07 % for <92.0 N for MLO) and low pressure (1.07 % for <7.2 kPa for MLO). No association was found between force or pressure as continuous exposures and early performance measures in adjusted regression analyses. CONCLUSIONS: We found the highest rates of screen-detected cancer for low force and pressure, but no significant association between continuous values of force or pressure and early performance measures in DBT. The findings might indicate that the levels of force and pressure in DBT are of lower significance for screening performance than reported in standard digital mammography.

Visualization of the Nipple in Profile: Does It Really Affect Selected Outcomes in Organized Mammographic Screening?

OBJECTIVE: To investigate whether having the nipple imaged in profile was associated with breast characteristics or compression parameters, and whether it affected selected outcomes in screening with standard digital mammography or digital breast tomosynthesis. METHODS: In this IRB-approved retrospective study, results from 87 450 examinations (174 900 breasts) performed as part of BreastScreen Norway, 2016-2019, were compared by nipple in profile status and screening technique using descriptive statistics and generalized estimating equations. Unadjusted and adjusted odds ratios with 95% confidence intervals (95% CIs) were estimated for outcomes of interest, including age, breast volume, volumetric breast density, and compression force as covariates. RESULTS: Achieving the nipple in profile versus not in profile was associated with lower breast volume (845.1 cm3 versus 1059.9 cm3, P < 0.01) and higher mammographic density (5.6% versus 4.4%, P < 0.01). Lower compression force and higher compression pressure were applied to breasts with the nipple in profile (106.6 N and 11.5 kPa) compared to the nipple not in profile (110.8 N and 10.5 kPa, P < 0.01 for both). The adjusted odds ratio was 0.95 (95% CI: 0.88-1.02; P = 0.15) for recall and 0.92 (95% CI: 0.77-1.10; P = 0.36) for screen-detected cancer for nipple in profile versus not in profile. CONCLUSION: Breast characteristics and compression parameters might hamper imaging of the nipple in profile. However, whether the nipple was in profile or not on the screening mammograms did not influence the odds of recall or screen-detected cancer, regardless of screening technique.

Self-reported Pain Associated With Screening With Digital Breast Tomosynthesis.

OBJECTIVE: We aimed to investigate self-reported pain during screening with digital breast tomosynthesis (DBT). METHODS: The study was approved by the Regional Committee for Medical and Health Research Ethics in the South East of Norway (2015/424). Women completed a questionnaire about experienced pain directly after the examination, August-November 2019. A numeric rating scale (NRS, 0-10) was used. Data on compression force (N), pressure (kPa), and compressed breast thickness (mm) were obtained from the Digital Imaging and Communication in Medicine header and density assessment software. Stepwise ordinary least-squares regression was used to estimate mean self-reported pain score with 95% confidence interval (CI) for values of compression force, pressure, and compressed breast thickness. RESULTS: The mean pain score was 1.9, whereof 19.3% (822/4266) of the women reported moderate or severe pain. The mean pain score of 2.6 (95% CI: 2.4-2.7) was observed at a compression force of 60 N, decreasing to 1.3 (95% CI: 1.2-1.4) at 130 N. The mean pain score of 1.3 (95% CI: 1.1-1.4) was at a compression pressure of 6 kPa, increasing to 2.9 (95% CI: 2.7-3.1) at 16 kPa. The mean pain score was 0.6 (95% CI: 0.4-0.6) at a compressed breast thickness of 20 mm, increasing to 2.9 (95% CI: 2.7-3.1) at 90 mm. CONCLUSION: The mean pain score was low, 1.9 on NRS, for women screened with DBT. A compression force of 60-130 N and a pressure 6-16 kPa were associated with no or mild pain.

Comparing Screening Outcomes for Digital Breast Tomosynthesis and Digital Mammography by Automated Breast Density in a Randomized Controlled Trial: Results from the To-Be Trial.

Background Digital breast tomosynthesis (DBT) is considered superior to digital mammography (DM) for women with dense breasts. Purpose To identify differences in screening outcomes, including rates of recall, false-positive (FP) findings, biopsy, cancer detection rate, positive predictive value of recalls and biopsies, and histopathologic tumor characteristics by density using DBT combined with two-dimensional synthetic mammography (SM) (hereafter, DBT+SM) versus DM. Materials and Methods This randomized controlled trial comparing DBT+SM and DM was performed in Bergen as part of BreastScreen Norway, 2016-2017. Automated software measured density (Volpara Density Grade [VDG], 1-4). The outcomes were compared for DBT+SM versus DM by VDG in descriptive analyses. A stratified log-binomial regression model was used to estimate relative risk of outcomes in subgroups by screening technique. Results Data included 28 749 women, 14 380 of whom were screened with DBT+SM and 14 369 of whom were screened with DM (both groups: median age, 59 years; interquartile range [IQR], 54-64 years). The recall rate was lower for women screened with DBT+SM versus those screened with DM for VDG 1 (2.1% [81 of 3929] vs 3.3% [106 of 3212]; P = .001) and VDG 2 (3.2% [200 of 6216] vs 4.3% [267 of 6280]; P = .002). For DBT+SM, adjusted relative risk of recall (VDG 2: 1.8; P < .001; VDG 3: 2.4; P < .001; VDG 4: 1.8; P = .02) and screen-detected breast cancer (VDG 2: 2.4; P = .004; VDG 3: 2.8; P = .01; VDG 4: 2.8; P = .05) increased with VDG, whereas no differences were observed for DM (relative risk of recall for VDG 2: 1.3; P = .06; VDG 3: 1.1; P = .41; VDG 4: 1.1; P = .71; and relative risk of screen-detected breast cancer for VDG 2: 1.7; P = .13; VDG 3: 2.1; P = .06; VDG 4: 2.2; P = .15). Conclusion Screening with digital breast tomosynthesis combined with synthetic two-dimensional mammograms (DBT+SM) versus digital mammography (DM) yielded lower recall rates for women with Volpara Density Grade (VDG) 1 and VDG 2. Adjusted relative risk of recall and screen-detected breast cancer increased with denser breasts for DBT+SM but not for DM. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Sechopoulos and Athanasiou in this issue.

Breast compression and experienced pain during mammography by use of three different compression paddles.

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.

Automated Volumetric Analysis of Mammographic Density in a Screening Setting: Worse Outcomes for Women with Dense Breasts.

Purpose To describe screening outcomes from BreastScreen Norway stratified by volumetric breast density (VBD). Materials and Methods This retrospective study included data from 107 949 women aged 50-69 years (mean age ± standard deviation, 58.7 years ± 5.6) who underwent 307 015 screening examinations from 2007 to 2015. Automated software classified mammographic density as nondense (VBD <7.5%) or dense (VBD ≥7.5%). Rates and distributions of screening outcomes (recall, biopsy, screen-detected and interval breast cancer, positive predictive values of recall and of needle biopsy, sensitivity, specificity, and histopathologic tumor characteristics) were analyzed and stratified by density. Tests of proportions, including propensity score and t tests, were used. Results In 28% (87 021 of 307 015) of the screening examinations, the breasts were classified as dense. Recall rates for women with nondense versus dense breasts were 2.7% (5882 of 219 994) and 3.6% (3101 of 87 021); biopsy rates were 1.1% (2359 of 219 994) and 1.4% (1209 of 87 021); rates of screen-detected cancer were 5.5 (1210 of 219 994) and 6.7 (581 of 87 021) per 1000 examinations; and rates of interval breast cancer were 1.2 (199 of 165 324) and 2.8 (185 of 66 674) per 1000 examinations, respectively (P < .001 for all). Sensitivity was 82% (884 of 1083) for nondense breasts and 71% (449 of 634) for dense breasts, whereas specificity was 98% (160 973 of 164 440) and 97% (64 250 of 66 225), respectively (P < .001 for both). For screen-detected cancers, mean tumor diameter was 15.1 mm and 16.6 mm (P = .01), and lymph node-positive disease was found in 18% (170 of 936) and 24% (98 of 417) (P = .02) of women with nondense and dense breasts, respectively. Conclusion Screening examinations of women with dense breasts classified by using automated software resulted in higher recall rate, lower sensitivity, larger tumor diameter, and more lymph node-positive disease compared with women with nondense breasts.

The impact of compression force and pressure at prevalent screening on subsequent re-attendance in a national screening program.

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.

Comparison of subjective and fully automated methods for measuring mammographic density.

Background Breast radiologists of the Norwegian Breast Cancer Screening Program subjectively classified mammographic density using a three-point scale between 1996 and 2012 and changed into the fourth edition of the BI-RADS classification since 2013. In 2015, an automated volumetric breast density assessment software was installed at two screening units. Purpose To compare volumetric breast density measurements from the automated method with two subjective methods: the three-point scale and the BI-RADS density classification. Material and Methods Information on subjective and automated density assessment was obtained from screening examinations of 3635 women recalled for further assessment due to positive screening mammography between 2007 and 2015. The score of the three-point scale (I = fatty; II = medium dense; III = dense) was available for 2310 women. The BI-RADS density score was provided for 1325 women. Mean volumetric breast density was estimated for each category of the subjective classifications. The automated software assigned volumetric breast density to four categories. The agreement between BI-RADS and volumetric breast density categories was assessed using weighted kappa (kw). Results Mean volumetric breast density was 4.5%, 7.5%, and 13.4% for categories I, II, and III of the three-point scale, respectively, and 4.4%, 7.5%, 9.9%, and 13.9% for the BI-RADS density categories, respectively ( P for trend < 0.001 for both subjective classifications). The agreement between BI-RADS and volumetric breast density categories was kw = 0.5 (95% CI = 0.47-0.53; P < 0.001). Conclusion Mean values of volumetric breast density increased with increasing density category of the subjective classifications. The agreement between BI-RADS and volumetric breast density categories was moderate.