Cancer Yield and Patterns of Follow-up for BI-RADS Category 3 after Screening Mammography Recall in the National Mammography Database.

Background The literature supports the use of short-interval follow-up as an alternative to biopsy for lesions assessed as probably benign, Breast Imaging Reporting and Data System (BI-RADS) category 3, with an expected malignancy rate of less than 2%. Purpose To assess outcomes from 6-, 12-, and 24-month follow-up of probably benign findings first identified at recall from screening mammography in the National Mammography Database (NMD). Materials and Methods This retrospective study included women recalled from screening mammography with BI-RADS category 3 assessment at additional evaluation from January 2009 through March 2018 from 471 NMD facilities. Only the first BI-RADS category 3 occurrence for women aged 25 years or older with no personal history of breast cancer was analyzed, with biopsy or 2-year imaging follow-up. Cancer yield and positive predictive value of biopsies performed (PPV3) were determined at each follow-up. Results Among 45 202 women (median age, 55 years; range, 25-90 years) with a BI-RADS category 3 lesion, 1574 (3.5%) underwent biopsy at the time of lesion detection, yielding 72 cancers (cancer yield, 4.6%; 72 of 1574 women). For the remaining 43 628 women who accepted surveillance, 922 were seen within 90 days (with 78 lesions biopsied and 12 [15%] classified as malignant). The women still in surveillance (31 465 of 43 381 women [72.5%]) underwent follow-up mammography at 6 months. Of 3001 (9.5%) lesions biopsied, 456 (15.2%) were malignant (cancer yield, 1.5%; 456 of 31 465 women; 95% confidence interval [CI]: 1.3%, 1.6%). Among 18 748 of 25 997 women (72.1%) in surveillance who underwent follow-up at 12 months, 1219 (6.5%) underwent biopsy with 230 (18.9%) malignant lesions found (cancer yield, 1.2%; 230 of 18 748 women; 95% CI: 1.1%, 1.4%). Through 2-year follow-up, the biopsy rate was 11.2% (4894 of 43 628 women) with a cancer yield of 1.86% (810 malignancies found among 43 628 women; 95% CI: 1.73%, 1.98%) and a PPV3 of 16.6% (810 malignancies found among 4894 women). Conclusion In the National Mammography Database, Breast Imaging Reporting and Data System (BI-RADS) category 3 use is appropriate, with 1.86% cumulative cancer yield through 2-year follow-up. Of 810 malignancies, 468 (57.8%) were diagnosed at or before 6 months, validating necessity of short-interval follow-up of mammographic BI-RADS category 3 findings. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Moy in this issue.

Risk Stratification for Screening Mammography: Benefits and Harms.

OBJECTIVE: The purpose of this article is to compare commonly used breast cancer risk assessment models, describe the machine learning approach and big data in risk prediction, and summarize the potential benefits and harms of restrictive risk-based screening. CONCLUSION: The commonly used risk assessment models for breast cancer can be complex and cumbersome to use. Each model incorporates different sets of risk factors, which are weighted differently and can produce different results for the same patient. No model is appropriate for all subgroups of the general population and only one model incorporates mammographic breast density. Future development of risk prediction tools that are generalizable and simpler to use are needed in guiding clinical decisions.

Screening for Breast Cancer in Women Age 75 Years and Older.

OBJECTIVE: Older women undergoing regular mammography experience significant reductions in breast cancer mortality, except in women with severe comorbidities or limited life expectancy. Optimizing screening strategies requires informed discussions of benefits and risks given each woman's health status. CONCLUSION: This article will review the benefits and risks of screening mammography in women older than 75 years within the context of life expectancy and comorbidities and summarize the current recommendations from professional organizations for screening mammography in older women.

Screening Mammography in Women 40-49 Years Old: Current Evidence.

OBJECTIVE: Breast cancer is an important health problem for women 40-49 years old, yet screening mammography for this age group remains controversial. This article reviews recent guidelines and supporting evidence on screening mammography in women of this age group. CONCLUSION: Evidence supports the benefit of annual screening mammography in women 40-49 years old. Models of different breast cancer screening strategies consistently show the greatest breast cancer mortality reduction and life-years gained with annual screening starting when women reach 40 years old.

Harmonizing Breast Cancer Screening Recommendations: Metrics and Accountability.

OBJECTIVE: The purposes of this article are to summarize breast cancer screening recommendations and discuss their differences and similarities and to explain the differences between two national databases to aid in interpretation of their benchmarks. CONCLUSION: The American College of Radiology, American Cancer Society, and U.S. Preventive Services Task Force all agree that annual mammography beginning at age 40 saves the most lives, and all acknowledge a woman's right to choose when to begin and stop screening. The National Mammography Database (NMD) differs from the Breast Cancer Surveillance Consortium database in that it acquires data using the same approach used by almost all mammography facilities in the United States. Therefore, NMD benchmarks, which include standard metrics, provide more meaningful comparisons to help mammography facilities and radiologists improve performance.

Use of the probably benign (BI-RADS category 3) assessment for masses on breast MRI: Is it transferable to general clinical practice?

The purpose of this study was to identify potential BI-RADS 3 mass descriptors on breast magnetic resonance imaging by systematically defining positive predictive values (PPV). In a blinded retrospective review of BI-RADS 4 masses, reader 1 identified 132 masses and reader 2 identified 76 masses. PPV for mass descriptors and for descriptor combinations was determined. No mass descriptor resulted in a PPV ≤2% (BI-RADS 3 threshold). Descriptors with the lowest PPVs were circumscribed margin (8%), rim internal enhancement and persistent kinetics (13% each), and oval shape (15%). The results demonstrate the difficulty in transferring the theoretical concept of lesion surveillance to systematic clinical use.

Comparison of recommendations for screening mammography using CISNET models.

BACKGROUND: Currently, there are several different recommendations for screening mammography from major national health care organizations, including: 1) annual screening at ages 40 to 84 years; 2) screening annually at ages 45 to 54 years, then biennially at ages 55 to 79 years; and 3) biennial screening at ages 50 to 74 years. METHODS: Mean values of six Cancer Intervention and Surveillance Modeling Network (CISNET) models were used to compare these three screening mammography recommendations in terms of benefits and risks. RESULTS: Mean mortality reduction was greatest with the recommendation of annual screening at ages 40 to 84 years (39.6%), compared with the hybrid recommendation of screening annually at ages 45 to 54 years, then biennially at ages 55 to 79 years (30.8%), and the recommendation of biennial screening at ages 50 to 74 years (23.2%). For a single-year cohort of US women aged 40 years, assuming 100% compliance, more breast cancers deaths would be averted over their lifetime with annual screening starting at age 40 (29,369) than with the hybrid recommendation (22,829) or biennial screening ages 50-74 (17,153 based on 2009 CISNET estimates, 15,599 based on 2016 CISNET estimates). To achieve the greatest mortality benefit, this single-year cohort of women would have the greatest total number of screening mammograms, benign recalls, and benign biopsies performed over the course of screening by following annual screening starting at age 40 years (90.2 million, 6.8 million, and 481,269, respectively) than by following the hybrid recommendation (49.0 million, 4.1 million, and 286,288, respectively) or biennial screening at ages 50 to 74 years (27.3 million, 2.3 million, and 162,885, respectively). CONCLUSION: CISNET models demonstrate that the greatest mortality reduction is achieved with annual screening of women starting at age 40 years. Cancer 2017;123:3673-3680. © 2017 American Cancer Society.

The National Mammography Database: Preliminary Data.

OBJECTIVE: The purposes of our study were to analyze screening mammography data submitted to the National Mammography Database (NMD) since its inception to confirm data collection feasibility, to draw parallels to data from the Breast Cancer Surveillance Consortium (BCSC), and to examine trends over time. We also retrospectively evaluated practice-level variation in terms of practice type, practice setting, census region, and annual volume. MATERIALS AND METHODS: Data from 90 mammography facilities in the NMD registry were analyzed. The registry receives mammography data collected as part of standard clinical practice, including self-reported demographic information, clinical findings, screening mammography interpretation, and biopsy results. Outcome metrics calculated were cancer detection rate, recall rate, and positive predictive values for biopsy recommended (PPV2) and biopsy performed (PPV3). RESULTS: The NMD successfully collected and analyzed data for 3,181,437 screening mammograms performed between January 2008 and December 2012. Mean values for outcomes were cancer detection rate of 3.43 per 1000 (95% CI, 3.2-3.7), recall rate of 10% (95% CI, 9.3-10.7%), PPV2 of 18.5% (95% CI, 16.7-20.2%), and PPV3 of 29.2% (95% CI, 26.2-32.3%). No statistically significant difference was seen in performance measurements on the basis of practice type, practice setting, census region, or annual volume. NMD performance measurements parallel those reported by the BCSC. CONCLUSION: The NMD has become the fastest growing mammography registry in the United States, providing nationwide performance metrics and permitting comparison with published benchmarks. Our study shows the feasibility of using the NMD to audit mammography facilities and to provide current, ongoing benchmark data.

Improving Screening Mammography Outcomes Through Comparison With Multiple Prior Mammograms.

OBJECTIVE: The objective of the present study is to evaluate the effect of comparison with multiple prior mammograms on the outcomes of screening mammography relative to comparison with a single prior mammogram. MATERIALS AND METHODS: We retrospectively analyzed 46,288 consecutive screening mammograms performed at our institution for 22,792 women. We divided these examinations into three groups: those interpreted without comparison with prior mammograms, those interpreted in comparison with one prior examination, and those interpreted in comparison with two or more prior examinations. For each group, we determined the rate of examination recall. We also calculated the positive predictive value of recall (i.e., positive predictive value level 1 [PPV1]) and the cancer detection rate (CDR) for both the group of examinations compared with a single prior mammogram and the group compared with multiple prior mammograms. Generalized estimating equations with the logistic link function were used to determine the relative odds ratio of recall as a function of the number of comparisons, with adjustment made for age as a confounding variable. The Fisher exact test was performed to compare the PPV1 and the CDR in the different cohorts. RESULTS: The recall rate for mammograms interpreted without comparison with prior examinations was 16.6%, whereas that for mammograms compared with one prior examination was 7.8% and that for mammograms compared with two or more prior examinations was 6.3%. After adjustment was made for age, the odds ratio of recall for the group with multiple prior examinations relative to the group with a single prior examination was 0.864 (95% CI, 0.776-0.962; p = 0.0074). Statistically significant increases in the PPV1 of 0.05 (p = 0.0009) and in the CDR of 2.3 cases per 1000 examinations (p = 0.0481) were also noted for mammograms compared with multiple prior examinations relative to those compared with a single prior examination. CONCLUSION: Comparison with two or more prior mammograms resulted in a statistically significant reduction in the screening mammography recall rate and increases in the CDR and PPV1 relative to comparison with a single prior mammogram.

Impact of Breast Density Legislation on Breast Cancer Risk Assessment and Supplemental Screening: A Survey of 110 Radiology Facilities.

Breast density notification laws, passed in 19 states as of October 2014, mandate that patients be informed of their breast density. The purpose of this study is to assess the impact of this legislation on radiology practices, including performance of breast cancer risk assessment and supplemental screening studies. A 20-question anonymous web-based survey was emailed to radiologists in the Society of Breast Imaging between August 2013 and March 2014. Statistical analysis was performed using Fisher's exact test. Around 121 radiologists from 110 facilities in 34 USA states and 1 Canadian site responded. About 50% (55/110) of facilities had breast density legislation, 36% of facilities (39/109) performed breast cancer risk assessment (one facility did not respond). Risk assessment was performed as a new task in response to density legislation in 40% (6/15) of facilities in states with notification laws. However, there was no significant difference in performing risk assessment between facilities in states with a law and those without (p < 0.831). In anticipation of breast density legislation, 33% (16/48), 6% (3/48), and 6% (3/48) of facilities in states with laws implemented handheld whole breast ultrasound (WBUS), automated WBUS, and tomosynthesis, respectively. The ratio of facilities offering handheld WBUS was significantly higher in states with a law than in states without (p < 0.001). In response to breast density legislation, more than 33% of facilities are offering supplemental screening with WBUS and tomosynthesis, and many are performing formal risk assessment for determining patient management.

The developing asymmetry: revisiting a perceptual and diagnostic challenge.

Developing asymmetry is a subtype of asymmetry that has changed in appearance over time. This change implies a higher level of suspicion than other types of asymmetry. This article aims to clarify and review (a) the defining features of a developing asymmetry, (b) tools to facilitate its appropriate identification and evaluation at mammography and sonography, (c) relevant percutaneous biopsy considerations, and (d) benign and malignant pathologies that may present as developing asymmetries.

The Potential Impact of Risk-Based Screening Mammography in Women 40-49 Years Old.

OBJECTIVE: The purpose of this study was to determine the prevalence of very strong family history and extremely dense tissue in women 40-49 years old with breast cancer detected on screening mammography. MATERIALS AND METHODS: All cancers detected by screening mammography at our institution between January 1997 and November 2012 in 40- to 49-year-old women were retrospectively identified. Those with a personal history of breast cancer were excluded. Family history, breast density, type of malignancy, hormone receptor status, and lymph node status were recorded. RESULTS: One hundred thirty-six cases of breast cancer were identified on screening mammography in 40- to 49-year-old women; 50% were invasive cancers, and 50%, ductal carcinoma in situ. Very strong family history was absent in 88%, and extremely dense breast tissue was absent in 86%. Seventy-six percent of patients had neither very strong family history nor extremely dense breasts, including 79% of the cases of invasive cancers, of which 25% had axillary nodal involvement and 89% were estrogen receptor positive. CONCLUSION: Very strong family history and extremely dense breast tissue were absent in most 40- to 49-year-old women with breast cancer detected at screening mammography. These cancers were frequently invasive (often with nodal metastases) and treatable (hormone receptor positive). Reducing the number of women to be screened in this age group by using this risk-based approach would reduce the number of screen-detected cancers by more than 75%, thereby precluding the benefit of mortality reduction. Even using a risk-based strategy with an expanded definition of high risk that included any first-degree family history, extremely dense tissue, or both, 66% of malignancies would still be missed.

Patient and Radiologist Characteristics Associated With Accuracy of Two Types of Diagnostic Mammograms.

OBJECTIVE: Earlier studies of diagnostic mammography found wide unexplained variability in accuracy among radiologists. We assessed patient and radiologist characteristics associated with the interpretive performance of two types of diagnostic mammography. MATERIALS AND METHODS: Radiologists interpreting mammograms in seven regions of the United States were invited to participate in a survey that collected information on their demographics, practice setting, breast imaging experience, and self-reported interpretive volume. Survey data from 244 radiologists were linked to data on 274,401 diagnostic mammograms performed for additional evaluation of a recent abnormal screening mammogram or to evaluate a breast problem, between 1998 and 2008. These data were also linked to patients' risk factors and follow-up data on breast cancer. We measured interpretive performance by false-positive rate, sensitivity, and AUC. Using logistic regression, we evaluated patient and radiologist characteristics associated with false-positive rate and sensitivity for each diagnostic mammogram type. RESULTS: Mammograms performed for additional evaluation of a recent mammogram had an overall false-positive rate of 11.9%, sensitivity of 90.2%, and AUC of 0.894; examinations done to evaluate a breast problem had an overall false-positive rate of 7.6%, sensitivity of 83.9%, and AUC of 0.871. Multiple patient characteristics were associated with measures of interpretive performance, and radiologist academic affiliation was associated with higher sensitivity for both indications for diagnostic mammograms. CONCLUSION: These results indicate the potential for improved radiologist training, using evaluation of their own performance relative to best practices, and for improved clinical outcomes with health care system changes to maximize access to diagnostic mammography interpretation in academic settings.

Criteria for identifying radiologists with acceptable screening mammography interpretive performance on basis of multiple performance measures.

OBJECTIVE: Using a combination of performance measures, we updated previously proposed criteria for identifying physicians whose performance interpreting screening mammography may indicate suboptimal interpretation skills. MATERIALS AND METHODS: In this study, six expert breast imagers used a method based on the Angoff approach to update criteria for acceptable mammography performance on the basis of two sets of combined performance measures: set 1, sensitivity and specificity for facilities with complete capture of false-negative cancers; and set 2, cancer detection rate (CDR), recall rate, and positive predictive value of a recall (PPV1) for facilities that cannot capture false-negative cancers but have reliable cancer follow-up information for positive mammography results. Decisions were informed by normative data from the Breast Cancer Surveillance Consortium (BCSC). RESULTS: Updated combined ranges for acceptable sensitivity and specificity of screening mammography are sensitivity≥80% and specificity≥85% or sensitivity 75-79% and specificity 88-97%. Updated ranges for CDR, recall rate, and PPV1 are: CDR≥6 per 1000, recall rate 3-20%, and any PPV1; CDR 4-6 per 1000, recall rate 3-15%, and PPV1≥3%; or CDR 2.5-4.0 per 1000, recall rate 5-12%, and PPV1 3-8%. Using the original criteria, 51% of BCSC radiologists had acceptable sensitivity and specificity; 40% had acceptable CDR, recall rate, and PPV1. Using the combined criteria, 69% had acceptable sensitivity and specificity and 62% had acceptable CDR, recall rate, and PPV1. CONCLUSION: The combined criteria improve previous criteria by considering the interrelationships of multiple performance measures and broaden the acceptable performance ranges compared with previous criteria based on individual measures.

Suspicious Findings at Digital Breast Tomosynthesis Occult to Conventional Digital Mammography: Imaging Features and Pathology Findings.

To review the imaging and pathologic features of a series of lesions detected at digital breast tomosynthesis (DBT), which are occult to conventional digital mammography (DM). We retrospectively reviewed 268 consecutive breast imaging reporting and data system 4 and 5 lesions imaged with both DM and DBT at our facility from July 2012 through April 2013. For each lesion, we recorded the mammographic finding, breast density, mode of biopsy, and pathology results. A total of 19 lesions were identified at DBT that were occult to DM. Sixty three percent (12/19) of these lesions were identified in dense breasts. Architectural distortion was seen in 74% (14/19) of cases and spiculated masses accounted for the remaining 26% (5/19). The positive predictive value of biopsy was 53% (10/19). Seven cases were infiltrating ductal carcinomas and three were infiltrating lobular carcinomas. High-risk lesions accounted for 47% (9/19) of the lesions, the majority of which were radial scars 67% (6/9). Eighty four percent (16/19) of the lesions underwent ultrasound guided core biopsy while the remainder underwent magnetic resonance imaging guided core biopsy. DBT may demonstrate suspicious lesions that are occult to DM, particularly in women with dense breasts. Such lesions have a high likelihood of malignancy and warrant biopsy.

The evolution of breast imaging: past to present.

The practice of breast imaging has transitioned through a wide variety of technologic advances from the early days of direct-exposure film mammography to xeromammography to screen-film mammography to the current era of full-field digital mammography and digital breast tomosynthesis. Along with these technologic advances, organized screening, federal regulations based on the Mammography Quality Standards Act, and the development of the American College of Radiology Breast Imaging Reporting and Data System have helped to shape the specialty of breast imaging. With the development of breast ultrasonography and breast magnetic resonance imaging, both complementary to mammography, additional algorithms for diagnostic workup and screening high-risk subgroups of women have emerged. A substantial part of breast imaging practice these days also involves breast interventional procedures-both percutaneous biopsy to obtain tissue diagnosis and localization procedures to guide surgical excision. This article reviews the evolution of breast imaging starting from a historical perspective and progressing to the present day.

Effect of radiologists' diagnostic work-up volume on interpretive performance.

PURPOSE: To examine radiologists' screening performance in relation to the number of diagnostic work-ups performed after abnormal findings are discovered at screening mammography by the same radiologist or by different radiologists. MATERIALS AND METHODS: In an institutional review board-approved HIPAA-compliant study, the authors linked 651 671 screening mammograms interpreted from 2002 to 2006 by 96 radiologists in the Breast Cancer Surveillance Consortium to cancer registries (standard of reference) to evaluate the performance of screening mammography (sensitivity, false-positive rate [ FPR false-positive rate ], and cancer detection rate [ CDR cancer detection rate ]). Logistic regression was used to assess the association between the volume of recalled screening mammograms ("own" mammograms, where the radiologist who interpreted the diagnostic image was the same radiologist who had interpreted the screening image, and "any" mammograms, where the radiologist who interpreted the diagnostic image may or may not have been the radiologist who interpreted the screening image) and screening performance and whether the association between total annual volume and performance differed according to the volume of diagnostic work-up. RESULTS: Annually, 38% of radiologists performed the diagnostic work-up for 25 or fewer of their own recalled screening mammograms, 24% performed the work-up for 0-50, and 39% performed the work-up for more than 50. For the work-up of recalled screening mammograms from any radiologist, 24% of radiologists performed the work-up for 0-50 mammograms, 32% performed the work-up for 51-125, and 44% performed the work-up for more than 125. With increasing numbers of radiologist work-ups for their own recalled mammograms, the sensitivity (P = .039), FPR false-positive rate (P = .004), and CDR cancer detection rate (P < .001) of screening mammography increased, yielding a stepped increase in women recalled per cancer detected from 17.4 for 25 or fewer mammograms to 24.6 for more than 50 mammograms. Increases in work-ups for any radiologist yielded significant increases in FPR false-positive rate (P = .011) and CDR cancer detection rate (P = .001) and a nonsignificant increase in sensitivity (P = .15). Radiologists with a lower annual volume of any work-ups had consistently lower FPR false-positive rate , sensitivity, and CDR cancer detection rate at all annual interpretive volumes. CONCLUSION: These findings support the hypothesis that radiologists may improve their screening performance by performing the diagnostic work-up for their own recalled screening mammograms and directly receiving feedback afforded by means of the outcomes associated with their initial decision to recall. Arranging for radiologists to work up a minimum number of their own recalled cases could improve screening performance but would need systems to facilitate this workflow.

Predicting invasive breast cancer versus DCIS in different age groups.

BACKGROUND: Increasing focus on potentially unnecessary diagnosis and treatment of certain breast cancers prompted our investigation of whether clinical and mammographic features predictive of invasive breast cancer versus ductal carcinoma in situ (DCIS) differ by age. METHODS: We analyzed 1,475 malignant breast biopsies, 1,063 invasive and 412 DCIS, from 35,871 prospectively collected consecutive diagnostic mammograms interpreted at University of California, San Francisco between 1/6/1997 and 6/29/2007. We constructed three logistic regression models to predict the probability of invasive cancer versus DCIS for the following groups: women ≥ 65 (older group), women 50-64 (middle age group), and women < 50 (younger group). We identified significant predictors and measured the performance in all models using area under the receiver operating characteristic curve (AUC). RESULTS: The models for older and the middle age groups performed significantly better than the model for younger group (AUC = 0.848 vs, 0.778; p = 0.049 and AUC = 0.851 vs, 0.778; p = 0.022, respectively). Palpability and principal mammographic finding were significant predictors in distinguishing invasive from DCIS in all age groups. Family history of breast cancer, mass shape and mass margins were significant positive predictors of invasive cancer in the older group whereas calcification distribution was a negative predictor of invasive cancer (i.e. predicted DCIS). In the middle age group--mass margins, and in the younger group--mass size were positive predictors of invasive cancer. CONCLUSIONS: Clinical and mammographic finding features predict invasive breast cancer versus DCIS better in older women than younger women. Specific predictive variables differ based on age.

Educational interventions to improve screening mammography interpretation: a randomized controlled trial.

OBJECTIVE: The objective of our study was to conduct a randomized controlled trial of educational interventions that were created to improve performance of screening mammography interpretation. MATERIALS AND METHODS: We randomly assigned physicians who interpret mammography to one of three groups: self-paced DVD, live expert-led educational seminar, or control. The DVD and seminar interventions used mammography cases of varying difficulty and provided associated teaching points. Interpretive performance was compared using a pretest-posttest design. Sensitivity, specificity, and positive predictive value (PPV) were calculated relative to two outcomes: cancer status and consensus of three experts about recall. The performance measures for each group were compared using logistic regression adjusting for pretest performance. RESULTS: One hundred two radiologists completed all aspects of the trial. After adjustment for preintervention performance, the odds of improved sensitivity for correctly identifying a lesion relative to expert recall were 1.34 times higher for DVD participants than for control subjects (95% CI, 1.00-1.81; p = 0.050). The odds of an improved PPV for correctly identifying a lesion relative to both expert recall (odds ratio [OR] = 1.94; 95% CI, 1.24-3.05; p = 0.004) and cancer status (OR = 1.81; 95% CI, 1.01-3.23; p = 0.045) were significantly improved for DVD participants compared with control subjects, with no significant change in specificity. For the seminar group, specificity was significantly lower than the control group (OR relative to expert recall = 0.80; 95% CI, 0.64-1.00; p = 0.048; OR relative to cancer status = 0.79; 95% CI, 0.65-0.95; p = 0.015). CONCLUSION: In this randomized controlled trial, the DVD educational intervention resulted in a significant improvement in screening mammography interpretive performance on a test set, which could translate into improved interpretative performance in clinical practice.

Prevalent vs Incident Screen: Why Does It Matter?

There are important differences in the performance and outcomes of breast cancer screening in the prevalent compared to the incident screening rounds. The prevalent screen is the first screening examination using a particular imaging technique and identifies pre-existing, undiagnosed cancers in the population. The incident screen is any subsequent screening examination using that technique. It is expected to identify fewer cancers than the prevalent screen because it captures only those cancers that have become detectable since the prior screening examination. The higher cancer detection rate at prevalent relative to incident screening should be taken into account when analyzing the medical audit and effectiveness of new screening technologies.