Time trends in radiologists' interpretive performance at screening mammography from the community-based Breast Cancer Surveillance Consortium, 1996-2004

Radiologist Characteristics Associated with Interpretive Performance of Screening Mammography: A National Mammography Database (NMD) Study

Background Factors affecting radiologists' performance in screening mammography interpretation remain poorly understood. Purpose To identify radiologists characteristics that affect screening mammography interpretation performance. Materials and Methods This retrospective study included 1223 radiologists in the National Mammography Database (NMD) from 2008 to 2019 who could be linked to Centers for Medicare & Medicaid Services (CMS) datasets. NMD screening performance metrics were extracted. Acceptable ranges were defined as follows: recall rate (RR) between 5% and 12%; cancer detection rate (CDR) of at least 2.5 per 1000 screening examinations; positive predictive value of recall (PPV1) between 3% and 8%; positive predictive value of biopsies recommended (PPV2) between 20% and 40%; positive predictive value of biopsies performed (PPV3) between the 25th and 75th percentile of study sample; invasive CDR of at least the 25th percentile of the study sample; and percentage of ductal carcinoma in situ (DCIS) of at least the 25th percentile of the study sample. Radiologist characteristics extracted from CMS datasets included demographics, subspecialization, and clinical practice patterns. Multivariable stepwise logistic regression models were performed to identify characteristics independently associated with acceptable performance for the seven metrics. The most influential characteristics were defined as those independently associated with the majority of the metrics (at least four). Results Relative to radiologists practicing in the Northeast, those in the Midwest were more likely to achieve acceptable RR, PPV1, PPV2, and CDR (odds ratio [OR], 1.4-2.5); those practicing in the West were more likely to achieve acceptable RR, PPV2, and PPV3 (OR, 1.7-2.1) but less likely to achieve acceptable invasive CDR (OR, 0.6). Relative to general radiologists, breast imagers were more likely to achieve acceptable PPV1, invasive CDR, percentage DCIS, and CDR (OR, 1.4-4.4). Those performing diagnostic mammography were more likely to achieve acceptable PPV1, PPV2, PPV3, invasive CDR, and CDR (OR, 1.9-2.9). Those performing breast US were less likely to achieve acceptable PPV1, PPV2, percentage DCIS, and CDR (OR, 0.5-0.7). Conclusion The geographic location of the radiology practice, subspecialization in breast imaging, and performance of diagnostic mammography are associated with better screening mammography performance; performance of breast US is associated with lower performance. ^©RSNA, 2021 Online supplemental material is available for this article.

A deep learning-based automated diagnostic system for classifying mammographic lesions

BACKGROUND

Screening mammography has led to reduced breast cancer-specific mortality and is recommended worldwide. However, the resultant doctors' workload of reading mammographic scans needs to be addressed. Although computer-aided detection (CAD) systems have been developed to support readers, the findings are conflicting regarding whether traditional CAD systems improve reading performance. Rapid progress in the artificial intelligence (AI) field has led to the advent of newer CAD systems using deep learning-based algorithms which have the potential to reach human performance levels. Those systems, however, have been developed using mammography images mainly from women in western countries. Because Asian women characteristically have higher-density breasts, it is uncertain whether those AI systems can apply to Japanese women. In this study, we will construct a deep learning-based CAD system trained using mammography images from a large number of Japanese women with high quality reading.

METHODS

We will collect digital mammography images taken for screening or diagnostic purposes at multiple institutions in Japan. A total of 15,000 images, consisting of 5000 images with breast cancer and 10,000 images with benign lesions, will be collected. At least 1000 images of normal breasts will also be collected for use as reference data. With these data, we will construct a deep learning-based AI system to detect breast cancer on mammograms. The primary endpoint will be the sensitivity and specificity of the AI system with the test image set.

DISCUSSION

When the ability of AI reading is shown to be on a par with that of human reading, images of normal breasts or benign lesions that do not have to be read by a human can be selected by AI beforehand. Our AI might work well in Asian women who have similar breast density, size, and shape to those of Japanese women.

TRIAL REGISTRATION

UMIN, trial number UMIN000039009. Registered 26 December 2019, https://www.umin.ac.jp/ctr/.

Modeling the natural history of ductal carcinoma in situ based on population data

Background

The incidence of ductal carcinoma in situ (DCIS) has increased substantially since the introduction of mammography screening. Nevertheless, little is known about the natural history of preclinical DCIS in the absence of biopsy or complete excision.

Methods

Two well-established population models evaluated six possible DCIS natural history submodels. The submodels assumed 30%, 50%, or 80% of breast lesions progress from undetectable DCIS to preclinical screen-detectable DCIS; each model additionally allowed or prohibited DCIS regression. Preclinical screen-detectable DCIS could also progress to clinical DCIS or invasive breast cancer (IBC). Applying US population screening dissemination patterns, the models projected age-specific DCIS and IBC incidence that were compared to Surveillance, Epidemiology, and End Results data. Models estimated mean sojourn time (MST) in the preclinical screen-detectable DCIS state, overdiagnosis, and the risk of progression from preclinical screen-detectable DCIS.

Results

Without biopsy and surgical excision, the majority of DCIS (64–100%) in the preclinical screen-detectable state progressed to IBC in submodels assuming no DCIS regression (36–100% in submodels allowing for DCIS regression). DCIS overdiagnosis differed substantially between models and submodels, 3.1–65.8%. IBC overdiagnosis ranged 1.3–2.4%. Submodels assuming DCIS regression resulted in a higher DCIS overdiagnosis than submodels without DCIS regression. MST for progressive DCIS varied between 0.2 and 2.5 years.

Conclusions

Our findings suggest that the majority of screen-detectable but unbiopsied preclinical DCIS lesions progress to IBC and that the MST is relatively short. Nevertheless, due to the heterogeneity of DCIS, more research is needed to understand the progression of DCIS by grades and molecular subtypes.

A novel approach to background subtraction in contrast-enhanced dual-energy digital mammography with commercially available mammography devices: Polychromaticity correction

PURPOSE

Contrast-enhanced digital mammography is an image subtraction technique that is able to improve the detectability of lesions in dense breasts. One of the main sources of error, when the technique is performed by means of commercial mammography devices, is represented by the intrinsic polychromaticity of the x-ray beams. The aim of the work is to propose an iterative procedure, which only assumes the knowledge of a small set of universal quantities, to take into account the polychromaticity and correct the subtraction results accordingly.

METHODS

In order to verify the procedure, it has been applied to an analytical simulation of a target containing a contrast medium and to actual radiographs of a breast phantom containing cavities filled with a solution of the same medium.

RESULTS

The reconstructed densities of contrast medium were compared, showing very good agreement between the theoretical predictions and the experimental results already after the first iteration. Furthermore, the convergence of the iterative procedure was studied, showing that only a small number of iterations is necessary to reach limiting values.

CONCLUSIONS

The proposed procedure represents an efficient solution to the polychromaticity issue, qualifying therefore as a viable alternative to inverse-map functions.

Experimental feasibility of multistatic holography for breast microwave radar image reconstruction

PURPOSE

The goal of this study was to assess the experimental feasibility of circular multistatic holography, a novel breast microwave radar reconstruction approach, using experimental datasets recorded using a preclinical experimental setup. The performance of this approach was quantitatively evaluated by calculating the signal to clutter ratio (SCR), contrast to clutter ratio (CCR), tumor to fibroglandular response ratio (TFRR), spatial accuracy, and reconstruction time.

METHODS

Five datasets were recorded using synthetic phantoms with the dielectric properties of breast tissue in the 1-6 GHz range using a custom radar system developed by the authors. The datasets contained synthetic structures that mimic the dielectric properties of fibroglandular breast tissues. Four of these datasets the authors covered an 8 mm inclusion that emulated a tumor. A custom microwave radar system developed at the University of Manitoba was used to record the radar responses from the phantoms. The datasets were reconstructed using the proposed multistatic approach as well as with a monostatic holography approach that has been previously shown to yield the images with the highest contrast and focal quality.

RESULTS

For all reconstructions, the location of the synthetic tumors in the experimental setup was consistent with the position in the both the monostatic and multistatic reconstructed images. The average spatial error was less than 4 mm, which is half the spatial resolution of the data acquisition system. The average SCR, CCR, and TFRR of the images reconstructed with the multistatic approach were 15.0, 9.4, and 10.0 dB, respectively. In comparison, monostatic images obtained using the datasets from the same experimental setups yielded average SCR, CCR, and TFRR values of 12.8, 4.9, and 5.9 dB. No artifacts, defined as responses generated by the reconstruction method of at least half the energy of the tumor signatures, were noted in the multistatic reconstructions. The average execution time of the images formed using the proposed approach was 4 s, which is one order of magnitude faster than the current state-of-the-art time-domain multistatic breast microwave radar reconstruction algorithms.

CONCLUSIONS

The images generated by the proposed method show that multistatic holography is capable of forming spatially accurate images in real-time with signal to clutter levels and contrast values higher than other published monostatic and multistatic cylindrical radar reconstruction approaches. In comparison to the monostatic holographic approach, the images generated by the proposed multistatic approach had SCR values that were at least 50% higher. The multistatic images had CCR and TFRR values at least 200% greater than those formed using a monostatic approach.

Breast Tumor Prognostic Characteristics and Biennial vs Annual Mammography, Age, and Menopausal Status

IMPORTANCE

Screening mammography intervals remain under debate in the United States.

OBJECTIVE

To compare the proportion of breast cancers with less vs more favorable prognostic characteristics in women screening annually vs biennially by age, menopausal status, and postmenopausal hormone therapy (HT) use.

DESIGN, SETTING, AND PARTICIPANTS

This was a study of a prospective cohort from 1996 to 2012 at Breast Cancer Surveillance Consortium facilities. A total of 15,440 women ages 40 to 85 years with breast cancer diagnosed within 1 year of an annual or within 2 years of a biennial screening mammogram.

EXPOSURES

We updated previous analyses by using narrower intervals for defining annual (11-14 months) and biennial (23-26 months) screening.

MAIN OUTCOMES AND MEASURES

We defined less favorable prognostic characteristics as tumors that were stage IIB or higher, size greater than 15 mm, positive nodes, and any 1 or more of these characteristics. We used log-binomial regression to model the proportion of breast cancers with less favorable characteristics following a biennial vs annual screen by 10-year age groups and by menopausal status and current postmenopausal HT use.

RESULTS

Among 15,440 women with breast cancer, most were 50 years or older (13,182 [85.4%]), white (12,063 [78.1%]), and postmenopausal (9823 [63.6%]). Among 2027 premenopausal women (13.1%), biennial screeners had higher proportions of tumors that were stage IIB or higher (relative risk [RR], 1.28 [95% CI, 1.01-1.63]; P=.04), size greater than 15 mm (RR, 1.21 [95% CI, 1.07-1.37]; P=.002), and with any less favorable prognostic characteristic (RR, 1.11 [95% CI, 1.00-1.22]; P=.047) compared with annual screeners. Among women currently taking postmenopausal HT, biennial screeners tended to have tumors with less favorable prognostic characteristics compared with annual screeners; however, 95% CIs were wide, and differences were not statistically significant (for stage 2B+, RR, 1.14 [95% CI, 0.89-1.47], P=.29; size>15 mm, RR, 1.13 [95% CI, 0.98-1.31], P=.09; node positive, RR, 1.18 [95% CI, 0.98-1.42], P=.09; any less favorable characteristic, RR, 1.12 [95% CI, 1.00-1.25], P=.053). The proportions of tumors with less favorable prognostic characteristics were not significantly larger for biennial vs annual screeners among postmenopausal women not taking HT (eg, any characteristic: RR, 1.03 [95% CI, 0.95-1.12]; P=.45), postmenopausal HT users after subdividing by type of hormone use (eg, any characteristic: estrogen+progestogen users, RR, 1.16 [95% CI, 0.91-1.47]; P=.22; estrogen-only users, RR, 1.14 [95% CI, 0.94-1.37]; P=.18), or any 10-year age group (eg, any characteristic: ages 40-49 years, RR, .1.04 [95% CI, 0.94-1.14]; P=.48; ages 50-59 years, RR, 1.03 [95% CI, 0.94-1.12]; P=.58; ages 60-69 years, RR, 1.07 [95% CI, 0.97-1.19]; P=.18; ages 70-85 years, RR, 1.05 [95% CI, 0.94-1.18]; P=.35).

CONCLUSIONS AND RELEVANCE

Premenopausal women diagnosed as having breast cancer following biennial vs annual screening mammography are more likely to have tumors with less favorable prognostic characteristics. Postmenopausal women not using HT who are diagnosed as having breast cancer following a biennial or annual screen have similar proportions of tumors with less favorable prognostic characteristics.

Estimation of overdiagnosis using short-term trends and lead time estimates uncontaminated by overdiagnosed cases: Results from the Norwegian Breast Screening Programme

Background

Estimating overdiagnosis in cancer screening is complicated. Using observational data, estimation of the expected incidence in the screening period and taking account of lead time are two major problems.

Methods

Using data from the Cancer Registry of Norway and the Norwegian Breast Cancer Screening Programme, we estimated incidence trends, using age-specific trends by year in the pre-screening period (1985–95). We also estimated sojourn time and sensitivity using interval cancers only. Thus, lead time estimates were uncontaminated by overdiagnosed cases. Finally, we derived estimates of overdiagnosis separately for all cancers, and for invasive cancers only, correcting for lead time, using two different methods.

Results

Our results indicate that overdiagnosis of all cancers, invasive and in situ, constituted 15–17% of all screen-detected cancers in 1996–2009. For invasive cancers only, the corresponding figures were -2 to 7% in the same period, suggesting that a substantial proportion of the overdiagnosis in the Norwegian Programme was due to ductal carcinoma in situ.

Conclusion

Using short-term trends, instead of long, prior to screening was more effective in predicting incidence in the screening epoch. In addition, sojourn time estimation using symptomatic cancers only avoids over-correction for lead time and consequently underestimation of overdiagnosis. Longer follow-up will provide more precise estimates of overdiagnosis.

A Utility/Cost Analysis of Breast Cancer Risk Prediction Algorithms

Breast cancer risk prediction algorithms are used to identify subpopulations that are at increased risk for developing breast cancer. They can be based on many different sources of data such as demographics, relatives with cancer, gene expression, and various phenotypic features such as breast density. Women who are identified as high risk may undergo a more extensive (and expensive) screening process that includes MRI or ultrasound imaging in addition to the standard full-field digital mammography (FFDM) exam. Given that there are many ways that risk prediction may be accomplished, it is of interest to evaluate them in terms of expected cost, which includes the costs of diagnostic outcomes. In this work we perform an expected-cost analysis of risk prediction algorithms that is based on a published model that includes the costs associated with diagnostic outcomes (true-positive, false-positive, etc.). We assume the existence of a standard screening method and an enhanced screening method with higher scan cost, higher sensitivity, and lower specificity. We then assess expected cost of using a risk prediction algorithm to determine who gets the enhanced screening method under the strong assumption that risk and diagnostic performance are independent. We find that if risk prediction leads to a high enough positive predictive value, it will be cost-effective regardless of the size of the subpopulation. Furthermore, in terms of the hit-rate and false-alarm rate of the of the risk-prediction algorithm, iso-cost contours are lines with slope determined by properties of the available diagnostic systems for screening.

Impact of computer-aided detection systems on radiologist accuracy with digital mammography

OBJECTIVE

The purpose of this study was to assess the impact of computer-aided detection (CAD) systems on the performance of radiologists with digital mammograms acquired during the Digital Mammographic Imaging Screening Trial (DMIST).

MATERIALS AND METHODS

Only those DMIST cases with proven cancer status by biopsy or 1-year follow-up that had available digital images were included in this multireader, multicase ROC study. Two commercially available CAD systems for digital mammography were used: iCAD SecondLook, version 1.4; and R2 ImageChecker Cenova, version 1.0. Fourteen radiologists interpreted, without and with CAD, a set of 300 cases (150 cancer, 150 benign or normal) on the iCAD SecondLook system, and 15 radiologists interpreted a different set of 300 cases (150 cancer, 150 benign or normal) on the R2 ImageChecker Cenova system.

RESULTS

The average AUC was 0.71 (95% CI, 0.66-0.76) without and 0.72 (95% CI, 0.67-0.77) with the iCAD system (p = 0.07). Similarly, the average AUC was 0.71 (95% CI, 0.66-0.76) without and 0.72 (95% CI 0.67-0.77) with the R2 system (p = 0.08). Sensitivity and specificity differences without and with CAD for both systems also were not significant.

CONCLUSION

Radiologists in our studies rarely changed their diagnostic decisions after the addition of CAD. The application of CAD had no statistically significant effect on radiologist AUC, sensitivity, or specificity performance with digital mammograms from DMIST.

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.

Personalized estimates of radiation dose from dedicated breast CT in a diagnostic population and comparison with diagnostic mammography

This study retrospectively analyzed the mean glandular dose (MGD) to 133 breasts from 132 subjects, all women, who participated in a clinical trial evaluating dedicated breast CT in a diagnostic population. The clinical trial was conducted in adherence to a protocol approved by institutional review boards and the study participants provided written informed consent. Individual estimates of MGD to each breast from dedicated breast CT was obtained by combining x-ray beam characteristics with estimates of breast dimensions and fibroglandular fraction from volumetric breast CT images, and using normalized glandular dose coefficients. For each study participant and for the breast corresponding to that imaged with breast CT, an estimate of the MGD from diagnostic mammography (including supplemental views) was obtained from the DICOM image headers for comparison. This estimate uses normalized glandular dose coefficients corresponding to a breast with 50% fibroglandular weight fraction. The median fibroglandular weight fraction for the study cohort determined from volumetric breast CT images was 15%. Hence, the MGD from diagnostic mammography was corrected to be representative of the study cohort. Individualized estimates of MGD from breast CT ranged from 5.7 to 27.8 mGy. Corresponding to the breasts imaged with breast CT, the MGD from diagnostic mammography ranged from 2.6 to 31.6 mGy. The mean (± inter-breast SD) and the median MGD (mGy) from dedicated breast CT exam were 13.9 ± 4.6 and 12.6, respectively. For the corresponding breasts, the mean (± inter-breast SD) and the median MGD (mGy) from diagnostic mammography were 12.4 ± 6.3 and 11.1, respectively. Statistical analysis indicated that at the 0.05 level, the distributions of MGD from dedicated breast CT and diagnostic mammography were significantly different (Wilcoxon signed ranks test, p = 0.007). While the interquartile range and the range (maximum-minimum) of MGD from dedicated breast CT was lower than diagnostic mammography, the median MGD from dedicated breast CT was approximately 13.5% higher than that from diagnostic mammography. The MGD for breast CT is based on a 1.45 mm skin layer and that for diagnostic mammography is based on a 4 mm skin layer; thus, favoring a lower estimate for MGD from diagnostic mammography. The median MGD from dedicated breast CT corresponds to the median MGD from four to five diagnostic mammography views. In comparison, for the same 133 breasts, the mean and the median number of views per breast during diagnostic mammography were 4.53 and 4, respectively. Paired analysis showed that there was approximately equal likelihood of receiving lower MGD from either breast CT or diagnostic mammography. Future work will investigate methods to reduce and optimize radiation dose from dedicated breast CT.

Contribution and performance of mobile units in an organized mammography screening program

BACKGROUND

The aims of this study were to evaluate the contribution of mobile mammography units to participation rate and to compare their performance to fixed screening centres within the organized mammography screening program of Quebec, Canada.

METHODS

The study is based on all screening mammograms carried out in women aged 50-69 who participated in the Québec program from 2002 to 2010. Performance was measured by screening sensitivity, false-positive rate (1-specificity), positive likelihood ratio as well as abnormal call rate, detection rate, interval cancer rate, positive predictive value, and tumour characteristics. Poisson regression models with robust variance estimation were used to take into account the multi-level structure of the data. All models were adjusted for characteristics related to women.

RESULTS

During the 2002-2010 period, 2,292,592 screening mammograms were performed, of which 42,279 (1.8%) were in mobile units. In regions serviced exclusively by mobile units, the participation rate reached an average of 63.4% during the 2006-2010 period compared to 54.7% for the entire study population. Estimated sensitivity was similar to that of fixed sites (rate ratio = 0.98 [0.84-1.15]) while the false-positive rate was lower (rate ratio = 0.76 [0.57-1.02]) although this difference was of marginal statistical significance (p=0.07).

CONCLUSIONS

In this program, mobile mammography units allowed regions lacking a fixed centre to attain participation rates slightly higher than those in the rest of Quebec, without loss of sensitivity and with some gain in the false-positive rate.

Estimating the relative utility of screening mammography

BACKGROUND

The concept of diagnostic utility is a fundamental component of signal detection theory, going back to some of its earliest works. Attaching utility values to the various possible outcomes of a diagnostic test should, in principle, lead to meaningful approaches to evaluating and comparing such systems. However, in many areas of medical imaging, utility is not used because it is presumed to be unknown.

METHODS

In this work, we estimate relative utility (the utility benefit of a detection relative to that of a correct rejection) for screening mammography using its known relation to the slope of a receiver operating characteristic (ROC) curve at the optimal operating point. The approach assumes that the clinical operating point is optimal for the goal of maximizing expected utility and therefore the slope at this point implies a value of relative utility for the diagnostic task, for known disease prevalence. We examine utility estimation in the context of screening mammography using the Digital Mammographic Imaging Screening Trials (DMIST) data.

RESULTS

We show how various conditions can influence the estimated relative utility, including characteristics of the rating scale, verification time, probability model, and scope of the ROC curve fit. Relative utility estimates range from 66 to 227.

CONCLUSIONS

We argue for one particular set of conditions that results in a relative utility estimate of 162 (±14%). This is broadly consistent with values in screening mammography determined previously by other means. At the disease prevalence found in the DMIST study (0.59% at 365-day verification), optimal ROC slopes are near unity, suggesting that utility-based assessments of screening mammography will be similar to those found using Youden's index.

Cumulative probability of false-positive recall or biopsy recommendation after 10 years of screening mammography: a cohort study

BACKGROUND

False-positive mammography results are common. Biennial screening may decrease the cumulative probability of false-positive results across many years of repeated screening but could also delay cancer diagnosis.

OBJECTIVE

To compare the cumulative probability of false-positive results and the stage distribution of incident breast cancer after 10 years of annual or biennial screening mammography.

DESIGN

Prospective cohort study.

SETTING

7 mammography registries in the National Cancer Institute-funded Breast Cancer Surveillance Consortium.

PARTICIPANTS

169,456 women who underwent first screening mammography at age 40 to 59 years between 1994 and 2006 and 4492 women with incident invasive breast cancer diagnosed between 1996 and 2006.

MEASUREMENTS

False-positive recalls and biopsy recommendations stage distribution of incident breast cancer.

RESULTS

False-positive recall probability was 16.3% at first and 9.6% at subsequent mammography. Probability of false-positive biopsy recommendation was 2.5% at first and 1.0% at subsequent examinations. Availability of comparison mammograms halved the odds of a false-positive recall (adjusted odds ratio, 0.50 [95% CI, 0.45 to 0.56]). When screening began at age 40 years, the cumulative probability of a woman receiving at least 1 false-positive recall after 10 years was 61.3% (CI, 59.4% to 63.1%) with annual and 41.6% (CI, 40.6% to 42.5%) with biennial screening. Cumulative probability of false-positive biopsy recommendation was 7.0% (CI, 6.1% to 7.8%) with annual and 4.8% (CI, 4.4% to 5.2%) with biennial screening. Estimates were similar when screening began at age 50 years. A non-statistically significant increase in the proportion of late-stage cancers was observed with biennial compared with annual screening (absolute increases, 3.3 percentage points [CI, -1.1 to 7.8 percentage points] for women age 40 to 49 years and 2.3 percentage points [CI, -1.0 to 5.7 percentage points] for women age 50 to 59 years) among women with incident breast cancer.

LIMITATIONS

Few women underwent screening over the entire 10-year period. Radiologist characteristics influence recall rates and were unavailable. Most mammograms were film rather than digital. Incident cancer was analyzed in a small sample of women who developed cancer.

CONCLUSION

After 10 years of annual screening, more than half of women will receive at least 1 false-positive recall, and 7% to 9% will receive a false-positive biopsy recommendation. Biennial screening appears to reduce the cumulative probability of false-positive results after 10 years but may be associated with a small absolute increase in the probability of late-stage cancer diagnosis.

PRIMARY FUNDING SOURCE

National Cancer Institute.

Comparative effectiveness of digital versus film-screen mammography in community practice in the United States: a cohort study

BACKGROUND

Few studies have examined the comparative effectiveness of digital versus film-screen mammography in U.S. community practice.

OBJECTIVE

To determine whether the interpretive performance of digital and film-screen mammography differs.

DESIGN

Prospective cohort study.

SETTING

Mammography facilities in the Breast Cancer Surveillance Consortium.

PARTICIPANTS

329,261 women aged 40 to 79 years underwent 869 286 mammograms (231 034 digital; 638 252 film-screen).

MEASUREMENTS

Invasive cancer or ductal carcinoma in situ diagnosed within 12 months of a digital or film-screen examination and calculation of mammography sensitivity, specificity, cancer detection rates, and tumor outcomes.

RESULTS

Overall, cancer detection rates and tumor characteristics were similar for digital and film-screen mammography, but the sensitivity and specificity of each modality varied by age, tumor characteristics, breast density, and menopausal status. Compared with film-screen mammography, the sensitivity of digital mammography was significantly higher for women aged 60 to 69 years (89.9% vs. 83.0%; P = 0.014) and those with estrogen receptor-negative cancer (78.5% vs. 65.8%; P = 0.016); borderline significantly higher for women aged 40 to 49 years (82.4% vs. 75.6%; P = 0.071), those with extremely dense breasts (83.6% vs. 68.1%; P = 0.051), and pre- or perimenopausal women (87.1% vs. 81.7%; P = 0.057); and borderline significantly lower for women aged 50 to 59 years (80.5% vs. 85.1%; P = 0.097). The specificity of digital and film-screen mammography was similar by decade of age, except for women aged 40 to 49 years (88.0% vs. 89.7%; P < 0.001).

LIMITATION

Statistical power for subgroup analyses was limited.

CONCLUSION

Overall, cancer detection with digital or film-screen mammography is similar in U.S. women aged 50 to 79 years undergoing screening mammography. Women aged 40 to 49 years are more likely to have extremely dense breasts and estrogen receptor-negative tumors; if they are offered mammography screening, they may choose to undergo digital mammography to optimize cancer detection.

PRIMARY FUNDING SOURCE

National Cancer Institute.

Cumulative probability of false-positive recall or biopsy recommendation after 10 years of screening mammography: a cohort study

BACKGROUND

False-positive mammography results are common. Biennial screening may decrease the cumulative probability of false-positive results across many years of repeated screening but could also delay cancer diagnosis.

OBJECTIVE

To compare the cumulative probability of false-positive results and the stage distribution of incident breast cancer after 10 years of annual or biennial screening mammography.

DESIGN

Prospective cohort study.

SETTING

7 mammography registries in the National Cancer Institute-funded Breast Cancer Surveillance Consortium.

PARTICIPANTS

169,456 women who underwent first screening mammography at age 40 to 59 years between 1994 and 2006 and 4492 women with incident invasive breast cancer diagnosed between 1996 and 2006.

MEASUREMENTS

False-positive recalls and biopsy recommendations stage distribution of incident breast cancer.

RESULTS

False-positive recall probability was 16.3% at first and 9.6% at subsequent mammography. Probability of false-positive biopsy recommendation was 2.5% at first and 1.0% at subsequent examinations. Availability of comparison mammograms halved the odds of a false-positive recall (adjusted odds ratio, 0.50 [95% CI, 0.45 to 0.56]). When screening began at age 40 years, the cumulative probability of a woman receiving at least 1 false-positive recall after 10 years was 61.3% (CI, 59.4% to 63.1%) with annual and 41.6% (CI, 40.6% to 42.5%) with biennial screening. Cumulative probability of false-positive biopsy recommendation was 7.0% (CI, 6.1% to 7.8%) with annual and 4.8% (CI, 4.4% to 5.2%) with biennial screening. Estimates were similar when screening began at age 50 years. A non-statistically significant increase in the proportion of late-stage cancers was observed with biennial compared with annual screening (absolute increases, 3.3 percentage points [CI, -1.1 to 7.8 percentage points] for women age 40 to 49 years and 2.3 percentage points [CI, -1.0 to 5.7 percentage points] for women age 50 to 59 years) among women with incident breast cancer.

LIMITATIONS

Few women underwent screening over the entire 10-year period. Radiologist characteristics influence recall rates and were unavailable. Most mammograms were film rather than digital. Incident cancer was analyzed in a small sample of women who developed cancer.

CONCLUSION

After 10 years of annual screening, more than half of women will receive at least 1 false-positive recall, and 7% to 9% will receive a false-positive biopsy recommendation. Biennial screening appears to reduce the cumulative probability of false-positive results after 10 years but may be associated with a small absolute increase in the probability of late-stage cancer diagnosis.

PRIMARY FUNDING SOURCE

National Cancer Institute.

Increasingly strong reduction in breast cancer mortality due to screening

BACKGROUND

Favourable outcomes of breast cancer screening trials in the 1970s and 1980s resulted in the launch of population-based service screening programmes in many Western countries. We investigated whether improvements in mammography and treatment modalities have had an influence on the effectiveness of breast cancer screening from 1975 to 2008.

METHODS

In Nijmegen, the Netherlands, 55,529 women received an invitation for screening between 1975 and 2008. We designed a case-referent study to evaluate the impact of mammographic screening on breast cancer mortality over time from 1975 to 2008. A total number of 282 breast cancer deaths were identified, and 1410 referents aged 50-69 were sampled from the population invited for screening. We estimated the effectiveness by calculating the odds ratio (OR) indicating the breast cancer death rate for screened vs unscreened women.

RESULTS

The breast cancer death rate in the screened group over the complete period was 35% lower than in the unscreened group (OR=0.65; 95% CI=0.49-0.87). Analysis by calendar year showed an increasing effectiveness from a 28% reduction in breast cancer mortality in the period 1975-1991 (OR=0.72; 95% CI=0.47-1.09) to 65% in the period 1992-2008 (OR=0.35; 95% CI=0.19-0.64).

CONCLUSION

Our results show an increasingly strong reduction in breast cancer mortality over time because of mammographic screening.

Influence of annual interpretive volume on screening mammography performance in the United States

PURPOSE

To examine whether U.S. radiologists' interpretive volume affects their screening mammography performance.

MATERIALS AND METHODS

Annual interpretive volume measures (total, screening, diagnostic, and screening focus [ratio of screening to diagnostic mammograms]) were collected for 120 radiologists in the Breast Cancer Surveillance Consortium (BCSC) who interpreted 783 965 screening mammograms from 2002 to 2006. Volume measures in 1 year were examined by using multivariate logistic regression relative to screening sensitivity, false-positive rates, and cancer detection rate the next year. BCSC registries and the Statistical Coordinating Center received institutional review board approval for active or passive consenting processes and a Federal Certificate of Confidentiality and other protections for participating women, physicians, and facilities. All procedures were compliant with the terms of the Health Insurance Portability and Accountability Act.

RESULTS

Mean sensitivity was 85.2% (95% confidence interval [CI]: 83.7%, 86.6%) and was significantly lower for radiologists with a greater screening focus (P = .023) but did not significantly differ by total (P = .47), screening (P = .33), or diagnostic (P = .23) volume. The mean false-positive rate was 9.1% (95% CI: 8.1%, 10.1%), with rates significantly higher for radiologists who had the lowest total (P = .008) and screening (P = .015) volumes. Radiologists with low diagnostic volume (P = .004 and P = .008) and a greater screening focus (P = .003 and P = .002) had significantly lower false-positive and cancer detection rates, respectively. Median invasive tumor size and proportion of cancers detected at early stages did not vary by volume.

CONCLUSION

Increasing minimum interpretive volume requirements in the United States while adding a minimal requirement for diagnostic interpretation could reduce the number of false-positive work-ups without hindering cancer detection. These results provide detailed associations between mammography volumes and performance for policymakers to consider along with workforce, practice organization, and access issues and radiologist experience when reevaluating requirements.

Effective biennial mammographic screening in women aged 40-49

BACKGROUND

The United Kingdom is currently moving the age limit for invitation in its national breast screening programme downwards from 50 to 47. In contrast, the US Preventive Services Task Force concluded that, because of borderline statistical significance on effectiveness of mammographic screening, the current evidence is insufficient to advise screening in women aged 40-49.

MATERIAL AND METHODS

We designed a case-referent study to investigate the effect of biennial mammographic screening on breast cancer mortality for women in their forties. In Nijmegen, the Netherlands, screening started in 1975. A total of 272 breast cancer deaths were identified, and 1360 referents aged 40-69 were sampled from the population invited for screening. Effectiveness was estimated by calculating the odds ratio (OR) indicating the breast cancer death rate in screened versus unscreened women.

RESULTS

In women aged 40-49, the effect of screening was OR = 0.50 (95% confidence interval (CI) = 0.30-0.82). This result is similar to those aged 50-59 (OR = 0.54; 95% CI = 0.35-0.85) and 60-69 (OR = 0.65; 95% CI = 0.38-1.13).

CONCLUSION

Our results add convincing evidence about the effectiveness of biennial mammographic screening in women aged 40-49.