Interval and Consecutive Round Breast Cancer after Digital Breast Tomosynthesis and Synthetic 2D Mammography versus Standard 2D Digital Mammography in BreastScreen Norway.

Background Screening that includes digital breast tomosynthesis (DBT) with two-dimensional (2D) synthetic mammography (SM) or standard 2D digital mammography (DM) results in detection of more breast cancers than does screening with DM alone. A decrease in interval breast cancer rates is anticipated but is not reported. Purpose To compare rates and characteristics of (a) interval breast cancer in women screened with DBT and SM versus those screened with DM alone and (b) screen-detected breast cancer at consecutive screenings with DM. Materials and Methods This prospective cohort study from BreastScreen Norway included women screened with DBT and SM (study group) or DM alone (control group) between February 2014 and December 2015 (baseline). All women, except nonattendees, women with breast cancer, and those who exceeded the upper age limit, were consecutively screened with DM after 2 years. Interval breast cancer, sensitivity, and specificity were estimated for women screened at baseline. Recall, screen-detected breast cancer, and positive predictive value were analyzed for consecutively screened women. A χ2 test, t test (P < .001 after Bonferroni correction indicated a significant difference), and binomial regression model were used to analyze differences across groups. Results A total of 92 404 women who underwent baseline screening (mean age, 59 years ± 6 [standard deviation]) were evaluated; 34 641 women in the study group (mean age, 59 years ± 6) were screened with DBT and SM and 57 763 women in the control group (mean age, 59 years ± 6) were screened with DM. A total of 26 474 women in the study group (mean age, 60 years ± 5) and 45 543 women in the control group (mean age, 60 years ± 5) were consecutively screened with DM. Rates of interval breast cancer were 2.0 per 1000 screened women in the study group and 1.5 per 1000 screened women in the control group (P = .12). No differences in histopathologic characteristics of interval breast cancer were observed. In the consecutive screening round, rates of screen-detected breast cancer were 3.9 per 1000 screened women (study group) and 5.6 per 1000 screened women (control group) (P = .001). Rates of histologic grade 1 invasive cancer were 0.5 per 1000 screened women (study group) and 1.3 per 1000 screened women (control group) (P = .001). Conclusion No differences in interval breast cancer rates or tumor characteristics were observed in women screened with DBT and SM compared with women screened with DM. Higher rates of low-grade screen-detected tumors were observed in the control group at consecutive screening. © RSNA, 2019 Online supplemental material is available for this article.

Pathway times in the mammography programme before and after introduction of the breast cancer care pathway. / Forløpstider i Mammografi-programmet før og etter innføring av pakkeforløp for brystkreft.

BACKGROUND: The purpose of introducing the 'cancer patient pathway for breast cancer' was to ensure a coherent treatment pathway without unnecessary delays. Radiologists and pathologists who work with breast diagnostics are involved in both cancer patient pathways and BreastScreen Norway. The extent to which this policy may have affected waiting times has not been analysed previously. This study presents waiting times in BreastScreen Norway before and after introduction of cancer patient pathway. MATERIAL AND METHOD: We analysed waiting times associated with 1 485 240 screening examinations undertaken as part of BreastScreen Norway in the period 01.7.2011-30.6.2018, stratified by breast diagnostic centre. Waiting times were defined as the number of calendar days from the a) screening examination to the dispatch of the negative results letter (dispatch time), b) screening examination to the date on which the follow-up examination was performed (follow-up examination time) and c) follow-up examination to diagnosis (diagnosis time). Data were retrieved from the Cancer Registry of Norway's databases. Use of these is set out in the Cancer Registry Regulations. We calculated median waiting times in addition to 90th percentiles. RESULTS: The median dispatch time was 13 days before the cancer patient pathway was introduced, and 12 days after. The median follow-up examination time increased from 23 to 27 days, while the median diagnosis time was 3 days both before and after introduction of the cancer patient pathway. INTERPRETATION: Dispatch and diagnosis times were unchanged, or slightly changed after introduction of the cancer patient pathway, while follow-up examination time increased somewhat. Introduction of the cancer patient pathway may have led to differential adjustments in priorities, workflows and access to resources between the breast diagnostic centres.

Screening outcome for consecutive examinations with digital breast tomosynthesis versus standard digital mammography in a population-based screening program.

OBJECTIVES: To retrospectively investigate early performance measures of digital breast tomosynthesis (DBT) versus standard digital mammography (DM) for consecutive screening rounds. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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. KEY POINTS: • 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.

Digital Breast Tomosynthesis and Synthetic 2D Mammography versus Digital Mammography: Evaluation in a Population-based Screening Program.

Purpose To compare the performance of digital breast tomosynthesis (DBT) and two-dimensional synthetic mammography (SM) with that of digital mammography (DM) in a population-based mammographic screening program. Materials and Methods In this prospective cohort study, data from 37 185 women screened with DBT and SM and from 61 742 women screened with DM as part of a population-based screening program in 2014 and 2015 were included. Early performance measures, including recall rate due to abnormal mammographic findings, rate of screen-detected breast cancer, positive predictive value of recall, positive predictive value of needle biopsy, histopathologic type, tumor size, tumor grade, lymph node involvement, hormonal status, Ki-67 level, and human epidermal growth factor receptor 2 status were compared in women who underwent DBT and SM screening and in those who underwent DM screening by using χ2 tests, two-sample unpaired t tests, and tests of proportions. Results Recall rates were 3.4% for DBT and SM screening and 3.3% for DM screening (P = .563). DBT and SM screening showed a significantly higher rate of screen-detected cancer compared with DM screening (9.4 vs 6.1 cancers per 1000 patients screened, respectively; P < .001). The rate of detection of tumors 10 mm or smaller was 3.2 per 1000 patients screened with DBT and SM and 1.8 per 1000 patients screened with DM (P < .001), and the rate of grade 1 tumors was 3.3 per 1000 patients screened with DBT and SM versus 1.4 per 1000 patients screened with DM (P < .001). On the basis of immunohistochemical analyses, rates of lymph node involvement and tumor subtypes did not differ between women who underwent DBT and SM screening and those who underwent DM screening. Conclusion DBT and SM screening increased the detection rate of histologically favorable tumors compared with that attained with DM screening. © RSNA, 2018 Online supplemental material is available for this article.

Digital breast tomosynthesis (DBT): initial experience in a clinical setting.

BACKGROUND: Digital breast tomosynthesis (DBT) is a promising new technology. Some experimental clinical studies have shown positive results, but the future role and indications of this new technique, whether in a screening or clinical setting, need to be evaluated. PURPOSE: To compare digital mammography and DBT in a side-by-side feature analysis for cancer conspicuity, and to assess whether there is a potential additional value of DBT to standard state-of-the-art conventional imaging work-up with respect to detection of additional malignancies. MATERIAL AND METHODS: The study had ethics committee approval. A total of 129 women underwent 2D digital mammography including supplementary cone-down and magnification views and breast ultrasonography if indicated, as well as digital breast tomosynthesis. The indication for conventional imaging in the clinical setting included a palpable lump in 30 (23%), abnormal mammographic screening findings in 54 (42%), and surveillance in 45 (35%) of the women. The women were examined according to present guidelines, including spot-magnification views, ultrasonography, and needle biopsies, if indicated. The DBT examinations were interpreted several weeks after the conventional imaging without knowledge of the conventional imaging findings. In a later session, three radiologists performed a side-by-side feature analysis for cancer conspicuity in a sample of 50 cases. RESULTS: State-of-the-art conventional imaging resulted in needle biopsy of 45 breasts, of which 20 lesions were benign and a total of 25 cancers were diagnosed. The remaining 84 women were dismissed with a normal/definitely benign finding and without indication for needle biopsy. The subsequent DBT interpretation found suspicious findings in four of these 84 women, and these four women had to be called back for repeated work-up with knowledge of the tomosynthesis findings. These delayed work-ups resulted in two cancers (increasing the cancer detection by 8%) and two false-positive findings. The side-by-side feature analysis showed higher conspicuity scores for tomosynthesis compared to conventional 2D for cancers presenting as spiculated masses and distortions. CONCLUSION: Tomosynthesis is a promising new technique. Our preliminary clinical experience shows that there is a potential for increasing the sensitivity using this new technique, especially for cancers manifesting as spiculated masses and distortions.

Number and characteristics of breast cancer cases diagnosed in four periods in the screening interval of a biennial population-based screening programme.

OBJECTIVE: To describe the distribution and prognostic tumour characteristics of interval breast cancers diagnosed in four periods after index screen (1-6, 7-12, 13-18 and 19+ months) in a population-based screening programme inviting women aged 50-69 years to biennial screening. SETTING: The Norwegian Breast Cancer Screening Programme (NBCSP) Methods: In all, 848 interval breast cancer cases were diagnosed in 437,235 screening examinations. The distribution and prognostic tumour characteristics of the interval cancers diagnosed in four periods in the screening interval will be described. Proportions and rates will be compared by chi(2)-test. RESULTS: A total of 70% of the interval cancers in the NBCSP were diagnosed in the second year of the interval. Except for tumour size (P = 0.027), we found no evidence of adverse prognostic breast characteristics (grade, lymph node involvement, oestrogen and progesterone receptor positive) in invasive tumours diagnosed during the second versus the first year of the screening interval (Chi square P > 0.05 for all). The prognostic characteristics of the tumours did not differ by age groups. It was a decreasing interval cancer rate per 10,000 women-years by age. CONCLUSION: The risk of interval cancer increases by time after index screen, and 70% of the interval cancers in the NBCSP were diagnosed in the second year of the interval. Prognostic histological tumour characteristics did not differ by time after index screen, thus mean sojourn time (tumour growth rate) seems important for stating an optimal screening interval in a population-based screening programme.

Influence of review design on percentages of missed interval breast cancers: retrospective study of interval cancers in a population-based screening program.

PURPOSE: To retrospectively investigate whether different review designs have an influence on the estimate of missed interval cancer in a population-based breast cancer screening program. MATERIALS AND METHODS: The Norwegian Breast Cancer Screening Program invites women aged 50-69 years to undergo biennial screening mammography. The current study was part of the evaluation and scientific aspects of the screening program and thus was covered by the general ethical approval of the screening program as a part of the Cancer Registry of Norway. All participants signed an informed consent that specified that data related to their screening visit could be used for evaluation and scientific purposes. Six radiologists (9-34 years of experience in mammography) reviewed previously obtained bilateral two-view screening and diagnostic mammograms of 231 interval cancers, 117 screening-detected cancers, and 373 normal cases. Four review designs were used: individual and paired blinded review and individual and consensus informed review. A five-point interpretation scale was used to reclassify the cancers into missed cancers, minimal signs, and true cancers. The number and proportion of subgroups were estimated with 95% confidence intervals. RESULTS: Of 231 interval cancers, 46 (19.9%) were reclassified as missed cancers with the mixed blinded individual review and 54 (23.4%) were classified as missed cancers with the mixed blinded paired review. Eighty-three cancers (35.9%) were classified as missed cancers with individual informed review, and 78 (33.8%) were classified as missed cancers with consensus informed review. Thirty-nine cancers (16.8%) were reclassified as missed when four or more radiologists assigned a score of 2 or more (probably benign or more suspicious); three cancers (1.3%) were reclassified as missed when a score of 4 or more (probably malignant or more suspicious) was assigned. CONCLUSION: The percentage of interval cancers classified as missed ranged from 1.3% to 35.9% according to review design. To encourage learning, a review protocol should include both blinded and informed designs.