Radiological surveillance of interval breast cancers in screening programmes

Accuracy of an Artificial Intelligence System for Interval Breast Cancer Detection at Screening Mammography

Background Artificial intelligence (AI) systems can be used to identify interval breast cancers, although the localizations are not always accurate. Purpose To evaluate AI localizations of interval cancers (ICs) on screening mammograms by IC category and histopathologic characteristics. Materials and Methods A screening mammography data set (median patient age, 57 years [IQR, 52-64 years]) that had been assessed by two human readers from January 2011 to December 2018 was retrospectively analyzed using a commercial AI system. The AI outputs were lesion locations (heatmaps) and the highest per-lesion risk score (range, 0-100) assigned to each case. AI heatmaps were considered false positive (FP) if they occurred on normal screening mammograms or on IC screening mammograms (ie, in patients subsequently diagnosed with IC) but outside the cancer boundary. A panel of consultant radiology experts classified ICs as normal or benign (true negative [TN]), uncertain (minimal signs of malignancy [MS]), or suspicious (false negative [FN]). Several specificity and sensitivity thresholds were applied. Mann-Whitney U tests, Kruskal-Wallis tests, and χ2 tests were used to compare groups. Results A total of 2052 screening mammograms (514 ICs and 1548 normal mammograms) were included. The median AI risk score was 50 (IQR, 32-82) for TN ICs, 76 (IQR, 41-90) for ICs with MS, and 89 (IQR, 81-95) for FN ICs (P = .005). Higher median AI scores were observed for invasive tumors (62 [IQR, 39-88]) than for noninvasive tumors (33 [IQR, 20-55]; P < .01) and for high-grade (grade 2-3) tumors (62 [IQR, 40-87]) than for low-grade (grade 0-1) tumors (45 [IQR, 26-81]; P = .02). At the 96% specificity threshold, the AI algorithm flagged 121 of 514 (23.5%) ICs and correctly localized the IC in 93 of 121 (76.9%) cases, with 48 FP heatmaps on the mammograms for ICs (rate, 0.093 per case) and 74 FP heatmaps on normal mammograms (rate, 0.048 per case). The AI algorithm correctly localized a lower proportion of TN ICs (54 of 427; 12.6%) than ICs with MS (35 of 76; 46%) and FN ICs (four of eight; 50% [95% CI: 13, 88]; P < .001). The AI algorithm localized a higher proportion of node-positive than node-negative cancers (P = .03). However, no evidence of a difference by cancer type (P = .09), grade (P = .27), or hormone receptor status (P = .12) was found. At 89.8% specificity and 79% sensitivity thresholds, AI detection increased to 181 (35.2%) and 256 (49.8%) of the 514 ICs, respectively, with FP heatmaps on 158 (10.2%) and 307 (19.8%) of the 1548 normal mammograms. Conclusion Use of a standalone AI system improved early cancer detection by correctly identifying some cancers missed by two human readers, with no differences based on histopathologic features except for node-positive cancers. © RSNA, 2024 Supplemental material is available for this article.

Breast cancer missed at screening; hindsight or mistakes?

PURPOSE

To investigate radiologists' interpretation scores of screening mammograms prior to diagnosis of screen-detected and interval breast cancers retrospectively classified as missed or true negative.

METHODS

We included data on radiologists' interpretation scores at screening prior to diagnosis for 1223 screen-detected and 1007 interval cancer cases classified as missed or true negative in an informed consensus-based review. All prior screening examinations were independently scored 1-5 by two radiologists; score 1 by both was considered concordant negative, score ≥ 2 by one radiologist discordant, and score ≥ 2 by both concordant positive. We analyzed associations between interpretation, review categories, mammographic features and histopathological findings using descriptive statistics and logistic regression.

RESULTS

Among screen-detected cancers, 31% of missed and 10% of true negative cancers had discordant or concordant positive interpretation at prior screening. The corresponding percentages for interval cancer were 21% and 8%. Age-adjusted odds ratio (OR) and 95% confidence interval (CI) for missed screen-detected cancer was 3.8 (95% CI: 2.6-5.4) after discordant and 5.5 (95% CI: 3.2-9.5) after concordant positive interpretation, using concordant negative as reference. Corresponding ORs for missed interval cancer were 3.0 (95% CI: 2.0-4.5) for discordant and 6.3 (95% CI: 2.3-17.5) for concordant positive interpretation. Asymmetry was the dominating mammographic feature at prior screening for all, except concordant positive screen-detected cancers where a mass dominated. Histopathological characteristics did not vary statistically with interpretation.

CONCLUSIONS

Most cancers were interpreted negatively at screening prior to diagnosis. Increased risk for missed screen-detected or interval cancer was observed after positive interpretation at prior screening.

Anticipating artificial intelligence in mammography screening: views of Swedish breast radiologists

OBJECTIVES

Artificial intelligence (AI) is increasingly tested and integrated into breast cancer screening. Still, there are unresolved issues regarding its possible ethical, social and legal impacts. Furthermore, the perspectives of different actors are lacking. This study investigates the views of breast radiologists on AI-supported mammography screening, with a focus on attitudes, perceived benefits and risks, accountability of AI use, and potential impact on the profession.

METHODS

We conducted an online survey of Swedish breast radiologists. As early adopter of breast cancer screening, and digital technologies, Sweden is a particularly interesting case to study. The survey had different themes, including: attitudes and responsibilities pertaining to AI, and AI's impact on the profession. Responses were analysed using descriptive statistics and correlation analyses. Free texts and comments were analysed using an inductive approach.

RESULTS

Overall, respondents (47/105, response rate 44.8%) were highly experienced in breast imaging and had a mixed knowledge of AI. A majority (n=38, 80.8%) were positive/somewhat positive towards integrating AI in mammography screening. Still, many considered there to be potential risks to a high/somewhat high degree (n=16, 34.1%) or were uncertain (n=16, 34.0%). Several important uncertainties were identified, such as defining liable actor(s) when AI is integrated into medical decision-making.

CONCLUSIONS

Swedish breast radiologists are largely positive towards integrating AI in mammography screening, but there are significant uncertainties that need to be addressed, especially regarding risks and responsibilities. The results stress the importance of understanding actor-specific and context-specific challenges to responsible implementation of AI in healthcare.

Interval cancer audit and disclosure in breast screening programmes: An international survey

OBJECTIVE AND SETTING

Accurate monitoring of interval cancers is important both for quality improvement and education and is a key parameter of breast screening quality assurance. Issues in relation to communication regarding interval cervical cancer in the Irish cervical screening programme were found, prompting interval cancer process review in all cancer screening programmes. An international survey to examine international consensus on interval breast cancer audit processes was conducted to inform Irish processes.

METHODS

A survey of 24 international population-based breast screening programmes was done to determine which undertook audit of interval breast cancer; if yes, they were asked (1) how they undertake audit, (2) if they obtain individual consent for audit and inform women of audit results, and (3) if disclosure of audit results occurs.

RESULTS

Response was 71% (17/24). Of these, 71% (12/17) have a programmatic audit process to calculate the interval cancer rate (ICR). Of these, ten also carry out radiological reviews, three using a blinded review. Two inform patients that audit is taking place; two provide choice to be in the audit; nine state that routine screening consent covers audit. For two of the five that have an open disclosure policy for medical incidents, this policy applies to screening interval cancers. One other country/region has an open disclosure policy for category 3 interval cancers only. Five have legal protection for interval cancers arising in the screened population.

CONCLUSION

While consistency in providing aggregate programmatic audits exists, there is no consistent approach to individual interval cancer reviews or results disclosure.

Considerations for Evaluating the Introduction of New Cancer Screening Technology: Use of Interval Cancers to Assess Potential Benefits and Harms

This framework focuses on the importance of the consideration of the downstream intermediate and long-term health outcomes when a change to a screening program is introduced. The authors present a methodology for utilising the relationship between screen-detected and interval cancer rates to infer the benefits and harms associated with a change to the program. A review of the previous use of these measures in the literature is presented. The framework presents other aspects to consider when utilizing this methodology, and builds upon an existing framework that helps researchers, clinicians, and policy makers to consider the impacts of changes to screening programs on health outcomes. It is hoped that this research will inform future evaluative studies to assess the benefits and harms of changes to screening programs.

Retrospective Review of Missed Cancer Detection and Its Mammography Findings with Artificial-Intelligence-Based, Computer-Aided Diagnosis

To investigate whether artificial-intelligence-based, computer-aided diagnosis (AI-CAD) could facilitate the detection of missed cancer on digital mammography, a total of 204 women diagnosed with breast cancer with diagnostic (present) and prior mammograms between 2018 and 2020 were included in this study. Two breast radiologists reviewed the mammographic features and classified them into true negative, minimal sign or missed cancer. They analyzed the AI-CAD results with an abnormality score and assessed whether the AI-CAD correctly localized the known cancer sites. Of the 204 cases, 137 were classified as true negative, 33 as minimal signs, and 34 as missed cancer. The sensitivity, specificity and diagnostic accuracy of AI-CAD were 84.7%, 91.5% and 86.3% on diagnostic mammogram and 67.2%, 91.2% and 83.38% on prior mammogram, respectively. The AI-CAD correctly localized 27 cases from 34 missed cancers on prior mammograms. The findings in the preceding mammography of AI-CAD-detected missed cancer were common in the order of calcifications, focal asymmetry and asymmetry. Asymmetry was the most common finding among the seven cases, which could not be detected by AI-CAD in the missed cases (5/7). The assistance of AI-CAD can be helpful in the early detection of breast cancer in mammography screenings.

Diagnostic Performance of AI for Cancers Registered in A Mammography Screening Program: A Retrospective Analysis

Purpose: To evaluate the performance of an artificial intelligence (AI) algorithm in a simulated screening setting and its effectiveness in detecting missed and interval cancers. Methods: Digital mammograms were collected from Bahcesehir Mammographic Screening Program which is the first organized, population-based, 10-year (2009-2019) screening program in Turkey. In total, 211 mammograms were extracted from the archive of the screening program in this retrospective study. One hundred ten of them were diagnosed as breast cancer (74 screen-detected, 27 interval, 9 missed), 101 of them were negative mammograms with a follow-up for at least 24 months. Cancer detection rates of radiologists in the screening program were compared with an AI system. Three different mammography assessment methods were used: (1) 2 radiologists’ assessment at screening center, (2) AI assessment based on the established risk score threshold, (3) a hypothetical radiologist and AI team-up in which AI was considered to be the third reader. Results: Area under curve was 0.853 (95% CI = 0.801-0.905) and the cut-off value for risk score was 34.5% with a sensitivity of 72.8% and a specificity of 88.3% for AI cancer detection in ROC analysis. Cancer detection rates were 67.3% for radiologists, 72.7% for AI, and 83.6% for radiologist and AI team-up. AI detected 72.7% of all cancers on its own, of which 77.5% were screen-detected, 15% were interval cancers, and 7.5% were missed cancers. Conclusion: AI may potentially enhance the capacity of breast cancer screening programs by increasing cancer detection rates and decreasing false-negative evaluations.

True and Missed Interval Cancer in Organized Mammographic Screening: A Retrospective Review Study of Diagnostic and Prior Screening Mammograms

RATIONALE AND OBJECTIVES

To explore radiological aspects of interval breast cancer in a population-based screening program.

MATERIALS AND METHODS

We performed a consensus-based informed review of mammograms from diagnosis and prior screening from women diagnosed with interval cancer 2004-2016 in BreastScreen Norway. Cases were classified as true (no findings on prior screening mammograms), occult (no findings at screening or diagnosis), minimal signs (minor/non-specific findings) and missed (obvious findings). We analyzed mammographic findings, density, time since prior screening, and histopathological characteristics between the classification groups.

RESULTS

The study included 1010 interval cancer cases. Mean age at diagnosis was 61 years (SD = 6), mean time between screening and diagnosis 14 months (SD = 7). A total of 48% (479/1010) were classified as true or occult, 28% (285/1010) as minimal signs and 24% (246/1010) as missed. We observed no differences in mammographic density between the groups, except from a higher percentage of dense breasts in women with occult cancer. Among cancers classified as missed, about 1/3 were masses and 1/3 asymmetries at prior screening. True interval cancers were diagnosed later in the screening interval than the other classification categories. No differences in histopathological characteristics were observed between true, minimal signs and missed cases.

CONCLUSION

In an informed review, 24% of the interval cancers were classified as missed based on visibility and mammographic findings on prior screening mammograms. Three out of four true interval cancers were diagnosed in the second year of the screening interval. We observed no statistical differences in histopathological characteristics between true and missed interval cancers.

Impact of Full-Field Digital Mammography Versus Film-Screen Mammography in Population Screening: A Meta-Analysis

BACKGROUND

Breast screening programs replaced film mammography with digital mammography, and the effects of this practice shift in population screening on health outcomes can be measured through examination of cancer detection and interval cancer rates.

METHODS

A systematic review and random effects meta-analysis were undertaken. Seven databases were searched for publications that compared film with digital mammography within the same population of asymptomatic women and reported cancer detection and/or interval cancer rates.

RESULTS

The analysis included 24 studies with 16 583 743 screening examinations (10 968 843 film and 5 614 900 digital). The pooled difference in the cancer detection rate showed an increase of 0.51 per 1000 screens (95% confidence interval [CI] = 0.19 to 0.83), greater relative increase for ductal carcinoma in situ (25.2%, 95% CI = 17.4% to 33.5%) than invasive (4%, 95% CI = -3% to 13%), and a recall rate increase of 6.95 (95% CI = 3.47 to 10.42) per 1000 screens after the transition from film to digital mammography. Seven studies (80.8% of screens) reported interval cancers: the pooled difference showed no change in the interval cancer rate with -0.02 per 1000 screens (95% CI = -0.06 to 0.03). Restricting analysis to studies at low risk of bias resulted in findings consistent with the overall pooled results for all outcomes.

CONCLUSIONS

The increase in cancer detection following the practice shift to digital mammography did not translate into a reduction in the interval cancer rate. Recall rates were increased. These results suggest the transition from film to digital mammography did not result in health benefits for screened women. This analysis reinforces the need to carefully evaluate effects of future changes in technology, such as tomosynthesis, to ensure new technology leads to improved health outcomes and beyond technical gains.

Survival among women diagnosed with screen-detected or interval breast cancer classified as true, minimal signs, or missed through an informed radiological review

OBJECTIVES

"True" breast cancers, defined as not being visible on prior screening mammograms, are expected to be more aggressive than "missed" cancers, which are visible in retrospect. However, the evidence to support this hypothesis is limited. We compared the risk of death from any cause for women with true, minimal signs, and missed invasive screen-detected (SDC) and interval breast cancers (IC).

METHODS

This nation-wide study included 1022 SDC and 788 IC diagnosed through BreastScreen Norway during 2005-2016. Cancers were classified as true, minimal signs, or missed by five breast radiologists in a consensus-based informed review of prior screening and diagnostic images. We used multivariable Cox regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the risk of death from any cause associated with true, minimal signs, and missed breast cancers, adjusting for age at diagnosis, histopathologic tumour diameter and grade, and subtype. Separate models were created for SDC and IC.

RESULTS

Among SDC, 463 (44%) were classified as true and 242 (23%) as missed; among IC, 325 (39%) were classified as true and 235 (32%) missed. Missed SDC were associated with a similar risk of death as true SDC (HR = 1.20, 95% CI (0.49, 2.46)). Similar results were observed for missed versus true IC (HR = 1.31, 95% CI (0.77, 2.23)).

CONCLUSIONS

We did not observe a statistical difference in the risk of death for women diagnosed with true or missed SDC or IC; however, the number of cases reviewed and follow-up time limited the precision of our estimates.

KEY POINTS

• An informed radiological review classified screen-detected and interval cancers as true, minimal signs, or missed based on prior screening and diagnostic mammograms. • It has been hypothesised that true cancers, not visible on the prior screening examination, may be more aggressive than missed cancers. • We did not observe a statistical difference in the risk of death from any cause for women with missed versus true screen-detected or interval breast cancers.

Retrospective radiological review and classification of interval breast cancers within population-based breast screening programmes for the purposes of open disclosure: A systematic review

INTRODUCTION

Interval breast cancers occur following a negative breast screening mammogram and before the next scheduled appointment within screening programmes. Radiological review classifies them as cancers that develop between screens, cancers with no obvious malignant abnormalities on prior screens or cancers not detected at screening. This study aimed to systematically review published literature on the occurrence of open disclosure following interval cancer radiological reviews by breast screening programmes internationally in a retrospective setting and examine methodologies used for radiological reviews for the purposes of disclosure.

METHODS

A search for relevant articles published (January 2000 - May 2019) was conducted according to PICO and PRISMA guidelines. The databases Pubmed, Scopus, Google Scholar, Cinahl, Web of Science, Embase, Science Direct and Global Health were searched. Relevant studies were reviewed if they had completed a retrospective review and classification of interval breast cancers.

RESULTS

Of 46 relevant articles included, no study was identified that conducted a retrospective review purposely for open disclosure. Retrospective reviews were conducted for audit/quality assurance, and research including for radiologist education and learning. Variation in methodology was found across review type (non-blinded/semi-informed approach), number of reviewers and classification categories. The proportion of false negative cancers classified among the studies ranged from 4 to 40 %.

DISCUSSION

Variation among radiological review practices were observed, which likely impacts classification results. To ensure standardised classification of interval breast cancers are employed for the purposes of open disclosure in screening settings, reproducible and consistent methodology is required.

Can artificial intelligence reduce the interval cancer rate in mammography screening?

Objectives

To investigate whether artificial intelligence (AI) can reduce interval cancer in mammography screening.

Materials and methods

Preceding screening mammograms of 429 consecutive women diagnosed with interval cancer in Southern Sweden between 2013 and 2017 were analysed with a deep learning–based AI system. The system assigns a risk score from 1 to 10. Two experienced breast radiologists reviewed and classified the cases in consensus as true negative, minimal signs or false negative and assessed whether the AI system correctly localised the cancer. The potential reduction of interval cancer was calculated at different risk score thresholds corresponding to approximately 10%, 4% and 1% recall rates.

Results

A statistically significant correlation between interval cancer classification groups and AI risk score was observed (p < .0001). AI scored one in three (143/429) interval cancer with risk score 10, of which 67% (96/143) were either classified as minimal signs or false negative. Of these, 58% (83/143) were correctly located by AI, and could therefore potentially be detected at screening with the aid of AI, resulting in a 19.3% (95% CI 15.9–23.4) reduction of interval cancer. At 4% and 1% recall thresholds, the reduction of interval cancer was 11.2% (95% CI 8.5–14.5) and 4.7% (95% CI 3.0–7.1). The corresponding reduction of interval cancer with grave outcome (women who died or with stage IV disease) at risk score 10 was 23% (8/35; 95% CI 12–39).

Conclusion

The use of AI in screen reading has the potential to reduce the rate of interval cancer without supplementary screening modalities.

Key Points

• Retrospective study showed that AI detected 19% of interval cancer at the preceding screening exam that in addition showed at least minimal signs of malignancy. Importantly, these were correctly localised by AI, thus obviating supplementary screening modalities.

• AI could potentially reduce a proportion of particularly aggressive interval cancers.

• There was a correlation between AI risk score and interval cancer classified as true negative, minimal signs or false negative.

[Preoperative breast imaging review: Interests and limits of specialized validation in oncology]

OBJECTIVES

To evaluate the impact of systematic radiological review by breast specialist radiologist of malignant breast lesion imaging on the therapeutic management of patients.

MATERIALS AND METHODS

Data collection was performed for patients with histopathologically proved breast cancer or suspicious breast lesion on imaging realized out of our institution. Patients underwent systematic mammary and axillary ultrasound, imaging review and if necessary complementary mammographic images. We analyzed the number of additional breast biopsies and axillary lymph node fine needle aspiration (FNA) with their histopathological results. We assessed their impact by comparing the final surgical treatment to the one planned before review.

RESULTS

Two hundred and seventeen patients were included, with a total of 230 BIRADS 0, 4, 5 or 6 breast lesions. Seventy-six additional breast core biopsies were realized, leading to diagnose 43 additional BIRADS 6 lesions (24 infiltrative carcinomas, 9 DCIS and 10 atypical lesions) in 30 patients (13.82%). Thirty-five additional lymph node FNA were realized with 12 metastatic nodes and 3 false negative samples. Imaging review lead to change surgical treatment in 59 patients (27.19%, P<0.01) with modification in breast surgery in 37 patients, axillary surgery in 8 patients and both sites surgery in 12 patients.

CONCLUSION

This study shows an impact of systematic radiological review by breast specialist radiologist in therapeutic management of patients treated for malignant breast lesion.

Breast Cancer Screening Program in Lithuania: Interval Cancers and Program Sensitivity After 7 Years of Mammography Screening

OBJECTIVE

Analysis of interval cancers is critical in determining the sensitivity of screening and represents an objective measure of the quality of mammography screening program (MSP).

METHODS

Period analyzed: from 2006 to 2012. The rate of screen-detected, interval cancers and program sensitivity were measured. A comparison of screen-detected and interval cancers was performed.

RESULTS

During the period of the study, 429 473 women were screened and 1297 were found to have cancer. The overall screen-detected cancer rate was 30.2 per 10 000 women screened. Four hundred thirty-one case of interval cancers have occurred during the period of the study. The interval cancer ratio (ICR) was 0.25. Overall sensitivity of MSP amounted to 75.1%. Slightly lower sensitivity was found among the youngest age-group, especially for those with lobular cancers. Interval cancers were bigger in size, more often with metastases in lymph nodes, than screen-detected cancers, but these differences were not statistically significant.

CONCLUSIONS

Overall program sensitivity in Lithuania is about 75%, ICR is 0.25, and these parameters are comparable to other European countries.

Association of symptoms and interval breast cancers in the mammography-screening programme: population-based matched cohort study

Background

We assessed the association between symptoms reported at breast cancer screening visits and interval cancers (ICs) in a prospective manner.

Methods

This population-based matched cohort study uses data of the Finnish National Breast Cancer Screening Programme that invites women aged 50–69 years old during 1992–2012. Subjects who attended screening with symptoms were matched with asymptomatic reference cohorts based on age at screening visit, year of invitation, number of invited visits and municipality of invitation. The primary outcome was ICs.

Results

Women with a lump had a threefold (hazard ratio 3.7, 95% confidence interval (CI) 3.0–4.6) risk of ICs and a higher risk (hazard ratio 1.7, 95% CI 1.4 to 2.0) at the subsequent visit compared with those without a lump. The fatal interval cancer risk increased by 0.39 per 1000 screens with a lump. The cumulative incidences of interval cancer increased within a month of a mammography-negative visit with a lump and after about 6 months of the visit with retraction or nipple discharge.

Conclusion

Women with breast symptoms have a clearly increased risk of interval breast cancer after the screening visit. Our findings indicate the need for different screening strategies in symptomatic women.

Silicone-based composite materials simulate breast tissue to be used as ultrasonography training phantoms

A silicone-based composite breast phantom is fabricated to be used as an education model in ultrasonography training. A matrix of silicone formulations is tracked to mimic the ultrasonography and tactile response of human breast tissue. The performance of two different additives: (i) silicone oil and (ii) vinyl-terminated poly (dimethylsiloxane) (PDMS) are monitored by a home-made acoustic setup. Through the use of 75 wt% vinyl-terminated PDMS in two-component silicone elastomer mixture, a sound velocity of 1.29 ± 0.09 × 10³ m/s and an attenuation coefficient of 12.99 ± 0.08 dB/cm-values those match closely to the human breast tissue-are measured with 5 MHz probe. This model can also be used for needle biopsy as well as for self-exam trainings. Herein, we highlight the fabrication of a realistic, durable, accessible, and cost-effective training platform that contains skin layer, inner breast tissue, and tumor masses.

Interval Cancers in Breast Cancer Screening: Comparison of Stage and Biological Characteristics with Screen-Detected Cancers or Incident Cancers in the Absence of Screening

Aims and background

To analyze stage distribution and biological features of interval cancers observed in Verona mammography screening compared to screen-detected cancers and “clinical” cancers occurring in the absence of screening, as provided by the Veneto Cancer Registry.

Methods and study design

Screen-detected cancers were identified in the screening archives. Interval cancers and clinical cancers (occurring in women never screened or not yet invited) were identified through the local cancer registry. Studied variables were age, stage, pathological pT and pN category, histological grading, estrogen and progesterone receptor status, and proliferation index (Ki67).

Results

We compared 95 interval cancers, 761 screen-detected cancers, and 1873 clinical cancer cases. Interval cancers had more aggressive features than screen-detected cancers, the difference being statistically significant for pT (P = 10–6), pN (P = 0.0003), grading (P = 0.007), estrogen receptors (P = 0.0006), and progesterone receptors (P = 0.00005), but not for Ki67 (P = 0.18). The features of interval cancers were not more aggressive than those of clinical cancers for pT (P = 0.84), pN (P = 0.33), grading (P = 0.61), estrogen receptors (P = 0.48), and progesterone receptors (P = 0.69), and were better for Ki67 (P = 0.02). In contrast, screen-detected cancers showed significantly better features than clinical cancers, for all studied variables: pT (P = 10–6), pN (P = 10–6), grading (P = 10–6), estrogen receptors (P = 10–5), progesterone receptors (P = 10–6), and Ki67 (P = 10–6).

Conclusions

Our findings are consistent with the length biased sampling hypothesis of interval cancers having a faster growth rate and a less favorable presentation than screen-detected cancers. Compared to clinical cancers, interval cancers had similar features, whereas screen-detected cancers had definitely more favorable features. This finding suggests, rather than a faster growth rate for interval cancers, a slower growth rate for screen-detected cancers, which, together with diagnostic anticipation, may explain a certain degree of overdiagnosis.

Mammographic density and risk of breast cancer by tumor characteristics: a case-control study

BACKGROUND

In a previous paper, we had assumed that the risk of screen-detected breast cancer mostly reflects inherent risk, and the risk of whether a breast cancer is interval versus screen-detected mostly reflects risk of masking. We found that inherent risk was predicted by body mass index (BMI) and dense area (DA) or percent dense area (PDA), but not by non-dense area (NDA). Masking, however, was best predicted by PDA but not BMI. In this study, we aimed to investigate if these associations vary by tumor characteristics and mode of detection.

METHODS

We conducted a case-control study nested within the Melbourne Collaborative Cohort Study of 244 screen-detected cases matched to 700 controls and 148 interval cases matched to 446 controls. DA, NDA and PDA were measured using the Cumulus software. Tumor characteristics included size, grade, lymph node involvement, and ER, PR, and HER2 status. Conditional and unconditional logistic regression were applied as appropriate to estimate the Odds per Adjusted Standard Deviation (OPERA) adjusted for age and BMI, allowing the association with BMI to be a function of age at diagnosis.

RESULTS

For screen-detected cancer, both DA and PDA were associated to an increased risk of tumors of large size (OPERA ~ 1.6) and positive lymph node involvement (OPERA ~ 1.8); no association was observed for BMI and NDA. For risk of interval versus screen-detected breast cancer, the association with risk for any of the three mammographic measures did not vary by tumor characteristics; an association was observed for BMI for positive lymph nodes (OPERA ~ 0.6). No associations were observed for tumor grade and ER, PR and HER2 status of tumor.

CONCLUSIONS

Both DA and PDA were predictors of inherent risk of larger breast tumors and positive nodal status, whereas for each of the three mammographic density measures the association with risk of masking did not vary by tumor characteristics. This might raise the hypothesis that the risk of breast tumours with poorer prognosis, such as larger and node positive tumours, is intrinsically associated with increased mammographic density and not through delay of diagnosis due to masking.

The epidemiology, radiology and biological characteristics of interval breast cancers in population mammography screening

An interval breast cancer is a cancer that emerges following a negative mammographic screen. This overview describes the epidemiology, and the radiological and biological characteristics of interval breast cancers in population mammography screening. Notwithstanding possible differences in ascertainment of interval breast cancers, there was broad variability in reported interval breast cancer rates (range 7.0 to 49.3 per 10,000 screens) reflecting heterogeneity in underlying breast cancer rates, screening rounds (initial or repeat screens), and the length and phase of the inter-screening interval. The majority of studies (based on biennial screening) reported interval breast cancer rates in the range of 8.4 to 21.1 per 10,000 screens spanning the two-year interval with the larger proportion occurring in the second year. Despite methodological limitations inherent in radiological surveillance (retrospective mammographic review) of interval breast cancers, this form of surveillance consistently reveals that the majority of interval cancers represent either true interval or occult cancers that were not visible on the index mammographic screen; approximately 20–25% of interval breast cancers are classified as having been missed (false-negatives). The biological characteristics of interval breast cancers show that they have relatively worse tumour prognostic characteristics and biomarker profile, and also survival outcomes, than screen-detected breast cancers; however, they have similar characteristics and prognosis as breast cancers occurring in non-screened women. There was limited evidence on the effect on interval breast cancer frequency and outcomes following transition from film to digital mammography screening.

Wavelet-based scaling indices for breast cancer diagnostics

Mammography is routinely used to screen for breast cancer. However, the radiological interpretation of mammogram images is complicated by the heterogeneous nature of normal breast tissue and the fact that cancers are often of the same radiographic density as normal tissue. In this work, we use wavelets to quantify spectral slopes of breast cancer cases and controls and demonstrate their value in classifying images. In addition, we propose asymmetry statistics to be used in forming features, which improve the classification result. For the best classification procedure, we achieve approximately 77% accuracy (sensitivity=73%, specificity=84%) in classifying mammograms with and without cancer. Copyright © 2017 John Wiley & Sons, Ltd.

Overdiagnosis of breast cancer in population screening: does it make breast screening worthless?

The risk of breast cancer (BC) overdiagnosis attributed to mammography screening is an unresolved issue, complicated by heterogeneity in the methodology of quantifying its magnitude, and both political and scientific elements surrounding interpretation of the evidence on this phenomenon. Evidence from randomized trials and also from observational studies shows that mammography screening reduces the risk of BC death; similarly, these studies provide sufficient evidence that overdiagnosis represents a serious harm from population breast screening. For both these outcomes of screening, BC mortality reduction and overdiagnosis, estimates of magnitude vary between studies however overdiagnosis estimates are associated with substantial uncertainty. The trade-off between the benefit and the collective harms of BC screening, including false-positives and overdiagnosis, is more finely balanced than initially recognized, however the snapshot of evidence presented on overdiagnosis does not mean that breast screening is worthless. Future efforts should be directed towards (a) ensuring that any changes in the implementation of BC screening optimize the balance between benefit and harms, including assessing how planned or actual changes modify the risk of overdiagnosis; (b) informing women of all the outcomes that may affect them when they participate in screening using well-crafted and balanced information; and (c) investing in research that will help define and reduce the ensuing overtreatment of screen-detected BC.

Mammographic density and risk of breast cancer by mode of detection and tumor size: a case-control study

BACKGROUND

Risk of screen-detected breast cancer mostly reflects inherent risk, while risk of interval cancer reflects inherent risk and risk of masking (risk of the tumor not being detected due to increased dense tissue). Therefore the predictors of whether a breast cancer is interval or screen-detected include those that predict masking. Our aim was to investigate the associations between mammographic measures and (1) inherent risk, and (2) masking.

METHODS

We conducted a case-control study nested within the Melbourne collaborative cohort study of 244 screen-detected cases (192 small tumors (<2 cm)) matched to 700 controls and 148 interval cases (76 small tumors) matched to 446 controls. Dense area (DA), percent dense area (PDA), and non-dense area (NDA) were measured using the Cumulus software. Conditional and unconditional logistic regression were applied as appropriate to estimate the odds per adjusted standard deviation (OPERA) adjusted for age and body mass index (BMI), allowing for the association with BMI to be a function of age at diagnosis. Tests of fit were performed using the Bayesian information criterion (BIC) and the area under the receiver operating characteristic curve.

RESULTS

For screen-detected cancer, the association with BMI had a marginally significant dependence on age at diagnosis, and after adjustment both DA and PDA were associated with risk (OPERA approximately 1.2) and gave a similar fit. NDA was not associated with risk. For interval cancer, the BMI risk association was not dependent on age at diagnosis and the best fitting model was PDA alone (OPERA = 2.24, 95 % confidence interval 1.75, 2.86). Prediction of interval versus screen-detected cancer was best achieved by PDA alone (OPERA = 1.76, 95 % confidence interval 1.39, 2.22) with no association with BMI. When the analysis was restricted to small tumors to reduce the influence of tumor growth, we obtained similar results.

CONCLUSIONS

Inherent breast cancer risk is predicted by BMI and DA or PDA, but not NDA. Masking is predicted by PDA, and not by BMI. Understanding risk and masking could help tailor mammographic screening.

Effect of short message service as a reminder on breast self-examination in breast cancer patients: a randomized controlled trial

This study was a single-blind randomized controlled trial to assess the effectiveness of SMS as a reminder for breast self-examination (BSE). Participants who underwent surgery for breast cancer were recruited and randomized to the intervention group or the control group. Subjects in the intervention group received one text message on the first day of every month that reminded them to complete monthly BSE and the other text message on the fifteenth day of every month that contained information about breast cancer. Primary and secondary outcomes were self-reported BSE adherence and the frequency of BSE over 6 months. Between August 2010 and December 2011, 216 patients were randomly assigned to the SMS group (n = 110) or the control group (n = 106). A total of 202 patients were included in the final analysis. Self-reported BSE adherence and the frequency of BSE over the past six months were significantly higher in the intervention group than in the control group. Multivariate analysis showed that the SMS was the only significant factor for BSE adherence (p < 0.001). The short-term results of our study suggest that SMS is an effective and low-cost method to enhance adherence to BSE with existing information technology infrastructure.

Methodological issues for determining intervals of subsequent cancer screening

The gap between nationwide recommendations of cancer screening and the related evidences obtained from Korean adults should be filled. Estimation of the mean sojourn time (MST) in a specific cancer is important to determine the intervals of subsequent screening. This author arranged the methods for calculating MST into 5 categories based on the parameters used. Under the legal barrier for protection of individual privacy and confidentiality in a Korean academic situation, the methods involving the use of transition rates or prevalence/incidence ratio would be applicable among these methods.

Clinicopathological differences between interval and screen-detected breast cancers diagnosed within a screening programme in Northern Portugal

Objective

To evaluate clinicopathological differences between screen-detected (SD) and interval (IC) breast cancers diagnosed in women enrolled in an organized breast screening programme in 2000--2007.

Setting

Breast Cancer Screening Programme of the north region of Portugal.

Methods

Using data from the screening programme and from the population-based North Region Cancer Registry, SD and IC were identified. Information on screening history, age, date of diagnosis, tumour size, histological type and grade, lymph node status, tumour stage, biomarkers, and treatment was obtained from the cancer registry and from clinical and pathological reports. Association between mode of detection and these clinicopathological characteristics was estimated by unconditional logistic regression.

Results

A total of 442 SD and 112 IC were identified in women aged 50--69. Compared with SD, IC were diagnosed in younger women (60.0 ± 5.8 years and 58.4 ± 6.0 years, respectively), were larger (tumour size >20 mm: 60.2% versus 25.1%), lobular (6.3% versus 16.1%), with a higher differentiation grade (grade 3: 17.7% versus 38.9%), had more lymph node metastases, more advanced stage, and oestrogen receptor (ER) negative (12.9% versus 29.0%) and progesterone negative, and HER2 positive. After multivariable analysis, compared with SD, IC were more likely to be larger than 20 mm, lobular, of grade 3 and negative for ER.

Conclusion

Our results are consistent with other studies. IC’s have a more aggressive biology than SDs. Our findings did not show any unexpected pattern requiring changes to our screening procedures, but continuous identification and characterization of IC is advisable.

What effect does mammographic breast density have on lesion detection in digital mammography?

Effective detection of breast cancer using mammography is an important public health issue worldwide. Breasts that contain higher levels of fibroglandular compared with fatty tissue increase breast radio-opacity making it more difficult to differentiate between normal and abnormal findings. The higher prevalence of breast cancer amongst women with denser breasts demands the origination of effective solutions to manage this common radiographic appearance. This brief review considers the impact of higher levels of density on cancer detection and the importance of digital technology in possibly reducing the negative effects of increased density.

Tumor phenotype and breast density in distinct categories of interval cancer: results of population-based mammography screening in Spain

INTRODUCTION

Interval cancers are tumors arising after a negative screening episode and before the next screening invitation. They can be classified into true interval cancers, false-negatives, minimal-sign cancers, and occult tumors based on mammographic findings in screening and diagnostic mammograms. This study aimed to describe tumor-related characteristics and the association of breast density and tumor phenotype within four interval cancer categories.

METHODS

We included 2,245 invasive tumors (1,297 screening-detected and 948 interval cancers) diagnosed from 2000 to 2009 among 645,764 women aged 45 to 69 who underwent biennial screening in Spain. Interval cancers were classified by a semi-informed retrospective review into true interval cancers (n = 455), false-negatives (n = 224), minimal-sign (n = 166), and occult tumors (n = 103). Breast density was evaluated using Boyd's scale and was conflated into: <25%; 25 to 50%; 50 to 75%; >75%. Tumor-related information was obtained from cancer registries and clinical records. Tumor phenotype was defined as follows: luminal A: ER+/HER2- or PR+/HER2-; luminal B: ER+/HER2+ or PR+/HER2+; HER2: ER-/PR-/HER2+; triple-negative: ER-/PR-/HER2-. The association of tumor phenotype and breast density was assessed using a multinomial logistic regression model. Adjusted odds ratios (OR) and 95% confidence intervals (95% CI) were calculated. All statistical tests were two-sided.

RESULTS

Forty-eight percent of interval cancers were true interval cancers and 23.6% false-negatives. True interval cancers were associated with HER2 and triple-negative phenotypes (OR = 1.91 (95% CI:1.22-2.96), OR = 2.07 (95% CI:1.42-3.01), respectively) and extremely dense breasts (>75%) (OR = 1.67 (95% CI:1.08-2.56)). However, among true interval cancers a higher proportion of triple-negative tumors was observed in predominantly fatty breasts (<25%) than in denser breasts (28.7%, 21.4%, 11.3% and 14.3%, respectively; <0.001). False-negatives and occult tumors had similar phenotypic characteristics to screening-detected cancers, extreme breast density being strongly associated with occult tumors (OR = 6.23 (95% CI:2.65-14.66)). Minimal-sign cancers were biologically close to true interval cancers but showed no association with breast density.

CONCLUSIONS

Our findings revealed that both the distribution of tumor phenotype and breast density play specific and independent roles in each category of interval cancer. Further research is needed to understand the biological basis of the overrepresentation of triple-negative phenotype among predominantly fatty breasts in true interval cancers.

Mammographic density and risk of breast cancer according to tumor characteristics and mode of detection: a Spanish population-based case-control study

INTRODUCTION

It is not clear whether high mammographic density (MD) is equally associated with all subtypes of breast cancer (BC). We investigated the association between MD and subsequent BC, considering invasiveness, means of detection, pathologic subtype, and the time elapsed since mammographic exploration and BC diagnosis.

METHODS

BC cases occurring in the population of women who attended screening from 1997 through 2004 in Navarre, a Spanish region with a fully consolidated screening program, were identified via record linkage with the Navarre Cancer Registry (n = 1,172). Information was extracted from the records of their first attendance at screening in that period. For each case, we randomly selected four controls, matched by screening round, year of birth, and place of residence. Cases were classified according to invasiveness (ductal carcinoma in situ (DCIS) versus invasive tumors), pathologic subtype (considering hormonal receptors and HER2), and type of diagnosis (screen-detected versus interval cases). MD was evaluated by a single, experienced radiologist by using a semiquantitative scale. Data on BC risk factors were obtained by the screening program in the corresponding round. The association between MD and tumor subtype was assessed by using conditional logistic regression.

RESULTS

MD was clearly associated with subsequent BC. The odds ratio (OR) for the highest MD category (MD >75%) compared with the reference category (MD <10%) was similar for DCIS (OR = 3.47; 95% CI = 1.46 to 8.27) and invasive tumors (OR = 2.95; 95% CI = 2.01 to 4.35). The excess risk was particularly high for interval cases (OR = 7.72; 95% CI = 4.02 to 14.81) in comparison with screened detected tumors (OR = 2.17; 95% CI = 1.40 to 3.36). Sensitivity analyses excluding interval cases diagnosed in the first year after MD assessment or immediately after an early recall to screening yielded similar results. No differences were seen regarding pathologic subtypes. The excess risk associated with MD persisted for at least 7 to 8 years after mammographic exploration.

CONCLUSIONS

Our results confirm that MD is an important risk factor for all types of breast cancer. High breast density strongly increases the risk of developing an interval tumor, and this excess risk is not completely explained by a possible masking effect.

[Classification and characteristics of interval cancers in the Principality of Asturias's Breast Cancer Screening Program]

OBJECTIVE

To review and classify the interval cancers found in the Principality of Asturias's Breast Cancer Screening Program (PDPCM). A secondary objective was to determine the histological characteristics, size, and stage of the interval cancers at the time of diagnosis.

MATERIAL AND METHODS

We included the interval cancers in the PDPCM in the period 2003-2007. Interval cancers were classified according to the breast cancer screening program protocol, with double reading without consensus, without blinding, with arbitration. Mammograms were interpreted by 10 radiologists in the PDPCM.

RESULTS

A total of 33.7% of the interval cancers could not be classified; of the interval cancers that could be classified, 40.67% were labeled true interval cancers, 31.4% were labeled false negatives on screening, 23.7% had minimal signs, and 4.23% were considered occult. A total of 70% of the interval cancers were diagnosed in the year of the period between screening examinations and 71.7% were diagnosed after subsequent screening. A total of 76.9% were invasive ductal carcinomas, 61.1% were stage II when detected, and 78.7% were larger than 10mm when detected.

CONCLUSIONS

The rate of interval cancers and the rate of false negatives in the PDPCM are higher than those recommended in the European guidelines. Interval cancers are diagnosed later than the tumors detected at screening. Studying interval cancers provides significant training for the radiologists in the PDPCM.

Proportional incidence and radiological review of large (T2+) breast cancers as surrogate indicators of screening programme performance

OBJECTIVES

Surrogate measures of screening performance [e.g. interval cancer (IC) proportional incidence] allow timely monitoring of sensitivity and quality. This study explored measures using large (T2+) breast cancers as potential indicators of screening performance.

METHODS

The proportional incidence of T2+ cancers (observed/expected cases) in a population-based screening programme (Trento, 2001-2009) was estimated. A parallel review of 'negative' preceding mammograms for screen-detected T2+ and for all ICs, using 'blinded' independent readings and case-mixes (54 T2+, 50 ICs, 170 controls) was also performed.

RESULTS

T2+ cancers were observed in 168 screening participants: 48 at first screen, 67 at repeat screening and 53 ICs. The T2+ estimated proportional incidence was 68% (observed/expected = 168/247), corresponding to an estimated 32% reduction in the rate of T2+ cancers in screening participants relative to that expected without screening. Majority review classified 27.8% (15/54) of T2+ and 28% (14/50) of ICs as screening error (P = 0.84), with variable recall rates amongst radiologists (8.8-15.2%).

CONCLUSIONS

T2+ review could be integrated as part of quality monitoring and potentially prove more feasible than IC review for some screening services.

KEY POINTS

• Interval breast cancers, assumed as screening failures, are monitored to estimate screening performance • Large (T2+) cancers at screening may also represent failed prior screening detection • Analysis of T2+ lesions may be more feasible than assessing interval cancers • Analysis of T2+ cancers is a potential further measure of screening performance.

Mammographic surveillance in women with a personal history of breast cancer: how accurate? How effective?

We review the accuracy and potential effect of mammography in surveillance of women with a personal history of breast cancer (PHBC). A literature review was performed to identify studies on screening mammography or breast surveillance reporting data on the accuracy or detection capability of mammography, or the effect of early detection of second breast cancers, in women with a PHBC. Evidence on mammography screening in women with PHBC comes from non-randomised studies, and is generally limited by several factors including design limitations. The proportion of ipsilateral breast recurrences detected with mammography ranges between 50% and 80% (including cancers detected also on clinical examination) but is lower at 8%-51% for mammography-only detection. Mammography detects approximately 45%-90% of contralateral cancers. There is evidence of a potential benefit for asymptomatic/early-detected second breast cancers (range of estimated hazard ratios: 0.10-0.86) relative to symptomatic or clinical-detection, in various surveillance strategies that include mammography, however these estimates are likely to have overestimated screening benefit. New evaluations of screening women with a PHBC are needed from screening programs or population datasets, to provide comprehensive measures of screening accuracy and outcomes in this population of women.

Comparison of interval breast cancer rates for two-versus single-view screening mammography: a population-based study

OBJECTIVE

To determine whether the implementation of two-view mammography was followed by a reduction in the rates of interval cancers.

MATERIAL AND METHOD

We analyzed the data concerning women aged 50-69 who attended the breast cancer screening program between January 1, 1994 and December 31, 2006 in Isère, France. We performed Poisson regressions to estimate age-adjusted rate ratios of women being recalled, cancer detection, and interval cancer for two-view compared to single-view mammography.

RESULTS

After adjusting for age, two-view mammography was associated with a higher risk of cancer detection (1.37 [95% CI, 1.16-1.62]) and with a decreased risk of 12-month (0.46 [95% CI, 0.23-0.92]) and 24-month (0.64 [95% CI, 0.46-0.88]) interval cancer.

CONCLUSION

Two-view mammography for first and subsequent screens is associated with lower rates of interval breast cancer. This is at the expense of an increased number of women being recalled for further assessment after subsequent screens.

Breast cancer screening: emerging role of new imaging techniques as adjuncts to mammography

Early detection of breast cancer has been shown to reduce breast cancer deaths in randomised controlled trials (RCTs) of mammography in women aged 50-69 years, with weaker evidence of benefit in those aged 40-49 or 70 years and older. Magnetic resonance imaging (MRI) and ultrasonography have been evaluated in breast cancer screening, relative to, or in addition to, mammography, in selected populations; neither test has been examined in an RCT, and thus evidence of associated screening benefit is uncertain. MRI is more sensitive than mammography in screening women with suspected or proven inherited mutations of the breast cancer genes. The addition of MRI in screening this population detects 8-24 additional cancers per 1000 screens, but also significantly increases a woman's risk of being recalled for investigation or surgical biopsy for false-positive findings. In Australia, Medicare funding for MRI screening of women in specific risk groups was announced in February 2009. Ultrasonography can detect cancers not identified on mammography in asymptomatic women with dense breast tissue. Incremental ultrasound cancer detection is reported in 0.27%-0.46% of women with mammography-negative dense breasts; evidence varies on its association with false-positive findings. Computer-aided detection (CAD) is a complementary tool to mammography, prompting the reader to consider lesions on the mammogram that may represent cancer. Emerging evidence and improved CAD technology are likely to help define its role in breast screening.

Analysis of interval cancers observed in an Italian mammography screening programme (2000-2006)

PURPOSE

The purpose of this study was to assess the interval cancer (IC) proportional incidence and review IC cases observed in an Italian mammography screening programme during 2000-2006.

MATERIALS AND METHODS

ICs were identified through linkage of a screening database with the local cancer registry and hospital discharge records to calculate proportional (observed/expected) incidence. Negatively reported mammograms preceding ICs underwent blind review (randomly mixed with negative controls in a 2:1 ratio) by three expert radiologists and classified according to European guidelines criteria (OC=occult, MS=minimal sign, SE=screening error) according to majority report. Proportional IC incidence and rate of reviewed IC classified as SE were compared with European guideline standards.

RESULTS

Proportional IC incidence was 10.8% in the first and 40.0% in the second year of the interval (European standard=30% or 50%, respectively). Sensitivity estimate for the 2-year interval was 74.6%. ICs were reviewed as SE, MS or OC in 15.0%, 14.0% or 71.0% of cases, respectively. Corresponding review results for negative controls were 7.0%, 25.0% or 68.0%, respectively. Positive predictive value for IC was 51.7% for SE and 21.8% for MS reporting category, respectively (p=0.008). European standard (<20% reviewed as SE) was reached.

CONCLUSIONS

The study shows that the sensitivity of the mammography programme was good, complying with European guideline recommendations. Assessment of IC-based early indicators of screening efficacy is feasible in a current screening programme and should become a routine procedure.

Interval cancer incidence and episode sensitivity in the Norrbotten Mammography Screening Programme, Sweden

OBJECTIVES

To estimate the interval cancer incidence, its determinants and the episode sensitivity in the Norrbotten Mammography Screening Programme (NMSP).

SETTING

Since 1989, women aged 40-74 years (n = 55,000) have been invited to biennial screening by the NMSP, Norrbotten county, Sweden.

METHODS

Data on 1047 invasive breast cancers from six screening rounds of the NMSP (1989-2002) were collected. We estimated the invasive interval cancer rates, rate ratios and the episode sensitivity using the detection and incidence methods. A linear Poisson-model was used to analyse association between interval cancer incidence and sensitivity.

RESULTS

768 screen-detected and 279 interval cancer cases were identified. The rate ratio of interval cancer decreased with age. The 50-59 year age group showed the highest rate ratio (RR = 0.52, 95% CI 0.41-0.65) and the 70-74 year age group the lowest (RR = 0.23, 95% CI 0.15-0.36). The rate ratios for the early (0-12 months) and late (13-24 months) interval cancers were similar (RR = 0.18, 95% CI 0.15-0.22 and 0.20, 95% CI 0.17-0.24). There was a significantly lower interval cancer incidence in the prevalence round as compared with the incidence rounds. According to the detection method the episode sensitivity increased with age from 57% in the age group 40-49 years to 84% in the age group 70-74 years. The corresponding figures for the incidence method were 50% and 77%, respectively.

CONCLUSION

Our study showed an interval cancer incidence of 38% and the episode sensitivity of 62-73%, depending on the method of calculation. Our results are of clinically acceptable level and concert with the reference values of the European guidelines.

Computer-assisted diagnosis (CAD) in mammography: comparison of diagnostic accuracy of a new algorithm (Cyclopus, Medicad) with two commercial systems

PURPOSE

The study compares the diagnostic accuracy (correct identification of cancer) of a new computer-assisted diagnosis (CAD) system (Cyclopus) with two other commercial systems (R2 and CADx).

MATERIALS AND METHODS

Cyclopus was tested on a set of 120 mammograms on which the two compared commercial systems had been previously tested. The set consisted of mammograms reported as negative, preceding 31 interval cancers reviewed as screening error or minimal sign, and of 89 verified negative controls randomly selected from the same screening database.

RESULTS

Cyclopus sensitivity was 74.1% (R2=54.8%; CADx=41.9%) and was higher for interval cancers reviewed as screening error (90.9%; R2=54.5%; CADx=81.8%) compared with those reviewed as minimal sign (65.0%; R2=55.0%; CADx=20.0%). Specificity was 15.7% (R2=29.2%; CADx=17.9%). Overall accuracy was 30.8% (R2=35.8%; CADx=24.1%). The positive predictive value of a case with CAD marks [regions of interest (ROI)] was 23.4% (23/98; R2=16.0%; CADx=15.1%). Average ROI number per view among negative controls was 1.13 (R2=0.93; CADx=0.99). Cyclopus was more sensitive for masses compared with isolated microcalcifications (208 vs 62 ROI; R2=90 vs 213; CADx=192 vs 130).

CONCLUSIONS

Compared with two other commercial systems, Cyclopus was more sensitive (R2 p=0.14; CADx p=0.02) and less specific (R2 p=0.02; CADx p=0.64).

Quality of mammography screening in the Milan programme: evidence of improved sensitivity based on interval cancer proportional incidence and radiological review

BACKGROUND

Interval cancer (IC) incidence and review-based initial evaluation of Milan service screening (ASLMI1) suggested suboptimal performance. We report results in a subsequent screening round to further determine screening quality.

METHODS

IC was identified in subjects with a negative screening episode in 2005 (N=33,258) by linkage with 2005-2007 Hospital Discharge Records. IC proportional incidence-based sensitivity was estimated. Radiological review, with case-mix, was conducted in a blinded manner. Linkage and review modalities were maintained as for initial evaluation.

RESULTS

30 identified IC accounted for 6.99% (year 1), 27.84% (year 2), and overall 17.44% (2-year screening interval) proportional incidence. Estimated sensitivity was 93.01% (year 1), 72.16% (year 2) and 82.55% (2-year interval). Review classified 5 (16.6%) as screening error, 2 (6.7%) as minimal signs, and 23 (76.7%) as occult.

CONCLUSION

Programme sensitivity is now within recommended European standards. Performance indicators improved relative to initial evaluation. Both increasing experience and formal training of radiologists are likely to have contributed to this improvement.