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

[Structured screening for sporadic breast cancer]

BACKGROUND

The aim of secondary prevention of breast cancer is to detect the disease at the earliest curable stage and thus to reduce breast cancer-specific mortality. To this end, the nationwide population-based mammography screening program (MSP) was set up in Germany in 2005 in addition to an interdisciplinary prevention project for high-risk groups.

OBJECTIVE

Overview of the current state of the MSP, the upcoming age expansion, and potential further developments.

MATERIAL AND METHODS

Narrative review article with topic-guided literature and data search.

RESULTS

Approximately 50% of the 70,500 new cases of breast cancer that occur each year are related to the age group of the MSP. 10 years after introduction of the MSP, the incidence of advanced breast cancer stages and breast cancer-related mortality of the screening target group have steadily decreased by about one quarter, while no relevant trends were seen in the neighboring age groups at the population level.

CONCLUSION

The MSP has effectively contributed to a reduction of breast cancer mortality. With the expansion of the age groups to 45-75 years, more women have access to structured, quality assured screening. With the use of advanced stratifications and diagnostics as well as artificial intelligence, the MSP could be further optimized.

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.

Evaluation of the interval cancer rate and its determinants on the Girona Health Region's early breast cancer detection program

BACKGROUND

The main aim of this study is to estimate the rate of false negative and true IC on the Program for the Early Detection of Breast Cancer (PEDBC) run by the Girona Health Region (GHR) and compare the clinicopathological characteristics of these tumors with those detected within the same program.

METHODS

A retrospective cohort study including all women participating on the Girona PEDBC between 2000 and 2006, with negative mammography screening. The IC included are those detected between the first and second round of screening and between the second and third round.

RESULTS

We identified a total of 43 IC, representing an incidence rate of 0.70 cases per 1,000 screened women. Of the 43 probable IC, we were able to classify a total of 22 (51.2%) cases. Of these 22 cases, 54.5% were classified as true interval tumors, 13.6% false negatives, 18.2% occult tumors and the remaining 13.6% minimal sign.We found significant differences in some clinicopathological characteristics of the IC comparing with the tumors detected within the program during the same period.

CONCLUSIONS

The IC rate for the PEDBC is within the expected parameters, with a high proportion of cases of true interval cancers (54.5%) and a low proportion of false negatives (13.6%). The results show that the proportional incidence of IC is within the limits set by European Guidelines. Furthermore, it has been confirmed that IC display more aggressive clinicopathological characteristics than screening breast cancers.

Seventeen-years overview of breast cancer inside and outside screening in Denmark

BACKGROUND

Long-term data on breast cancer detection in mammography screening programs are warranted to better understand the mechanisms by which screening changes the breast cancer pattern in the population. We aimed to analyze 17 years of breast cancer detection rates inside and outside screening in two Danish regions, emphasizing the influence of organizational differences of screening programs on the outcomes.

MATERIAL AND METHODS

We used data from two long-standing population-based mammography screening programs, Copenhagen and Fyn, in Denmark. Both programs offered biennial screening to women aged 50-69 years. We identified targeted, eligible, invited and participating women. We calculated screening detection and interval cancer rates for participants, and breast cancer incidence in non-screened women (= targeted women excluding participants) by biennial invitation rounds. Tumor characteristics were tabulated for each of the three groups of cancers.

RESULTS

Start of screening resulted in a prevalence peak in participants, followed by a decrease to a fairly stable detection rate in subsequent invitation rounds. A similar pattern was found for breast cancer incidence in non-screened women. In Fyn, non-screened women even had a higher rate than screening participants during the first three invitation rounds. The interval cancer rate was lower in Copenhagen than in Fyn, with an increase over time in Copenhagen, but not in Fyn. Screen-detected cancers showed tumor features related with a better prognosis than tumors detected otherwise, as more than 80% were smaller than 20 mm and estrogen receptor positive.

CONCLUSION

Data from two long-standing population-based screening programs in Denmark illustrated that even if background breast cancer incidence and organization were rather similar, performance indicators of screening could be strongly influenced by inclusion criteria and participation rates. Detection rates should be interpreted with caution as they may be biased by selection into the screening population.

A simple method to estimate the episode and programme sensitivity of breast cancer screening programmes

BACKGROUND

The estimation of breast cancer screening sensitivity is a major aim in the quality assessment of screening programmes. The proportional incidence method for the estimation of the sensitivity of breast cancer screening programmes is rarely used to estimate the underlying incidence rates.

METHODS

We present a method to estimate episode and programme sensitivity of screening programmes, based solely on cancers detected within screening cycles (excluding breast cancer cases at prevalent screening round) and on the number of incident cases in the total target population (steady state). The assumptions, strengths and limitations of the method are discussed. An example of calculation of episode and programme sensitivities is given, on the basis of the data from the IMPACT study, a large observational study of breast cancer screening programmes in Italy.

RESULTS

The programme sensitivity from the fifth year of screening onwards ranged between 41% and 48% of the total number of cases in the target population. At steady state episode sensitivity was 0.70, with a trend across age groups, with lowest values in women aged 50-54 years (0.52) and highest in those 65-69 (0.77).

CONCLUSIONS

The method is a very serviceable tool for estimating sensitivity in service screening programmes, and the results are comparable with those of other methods of estimation.

A pooled analysis of interval cancer rates in six European countries

The objective of this study was to assess detection rates and interval breast cancer (IC) rates from eight programmes in the European Breast Cancer Screening Network. A common data collection protocol was used to explore differences in IC rates among programmes and discuss their potential determinants. Pooled analysis was used to describe IC rates by age, compliance in screening, recall rate, screening detection (SD) rate and expected breast cancer incidence. Participation in screening averaged 77.9% (range 42.6-88.7%), recall rate 5.4% (range 3.3-17.7%) in the initial and 3.4% (range 1.8-8.9%) in the subsequent screening rounds, and SD rate was 60.4 (range 41.6-91) per 10 000 women in initial and 38.5 (range 31.3-62.6) in subsequent screens. IC rate during first 12 months after screening was 5.9 (range 2.1-7.3) per 10 000 women screened negative and 12.6 (range 6.3-15) in the second year of the interval. IC comprised 28% of the IC and SD cancers. The ratio between IC rate and expected incidence was 0.29 for the first 12 months and 0.63 for the 13-24 months period. Sensitivity was higher for the ages 60-69 years and for initial tests than subsequent tests. There were distinct differences in the IC rates between programmes. The results of this study reveal large variations in screening sensitivity and performance. Pooled evaluation of some process indicators within the European breast cancer screening programmes proved to be feasible and is likely to be useful for the future, particularly if it is performed regularly and extensively.

Comparing Interval Breast Cancer Rates in Norway and North Carolina: Results and Challenges

Objective

To compare interval breast cancer rates (ICR) between a biennial organized screening programme in Norway and annual opportunistic screening in North Carolina (NC) for different conceptualizations of interval cancer.

Setting

Two regions with different screening practices and performance.

Methods

620,145 subsequent screens (1996–2002) performed in women aged 50–69 and 1280 interval cancers were analysed. Various definitions and quantification methods for interval cancers were compared.

Results

ICR for one year follow-up were lower in Norway compared with NC both when the rate was based on all screens (0.54 versus 1.29 per 1000 screens), negative final assessments (0.54 versus 1.29 per 1000 screens), and negative screening assessments (0.53 versus 1.28 per 1000 screens). The rate of ductal carcinoma in situ was significantly lower in Norway than in NC for cases diagnosed in both the first and second year after screening. The distributions of histopathological tumour size and lymph node involvement in invasive cases did not differ between the two regions for interval cancers diagnosed during the first year after screening. In contrast, in the second year after screening, tumour characteristics remained stable in Norway but became prognostically more favorable in NC.

Conclusion

Even when applying a common set of definitions of interval cancer, the ICR was lower in Norway than in NC. Different definitions of interval cancer did not influence the ICR within Norway or NC. Organization of screening and screening performance might be major contributors to the differences in ICR between Norway and NC.

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.

Comparing screening mammography for early breast cancer detection in Vermont and Norway

BACKGROUND

Most screening mammography in the United States differs from that in countries with formal screening programs by having a shorter screening interval and interpretation by a single reader vs independent double reading. We examined how these differences affect early detection of breast cancer by comparing performance measures and histopathologic outcomes in women undergoing opportunistic screening in Vermont and organized screening in Norway.

METHODS

We evaluated recall, screen detection, and interval cancer rates and prognostic tumor characteristics for women aged 50-69 years who underwent screening mammography in Vermont (n = 45 050) and in Norway (n = 194 430) from 1997 through 2003. Rates were directly adjusted for age by weighting the rates within 5-year age intervals to reflect the age distribution in the combined data and were compared using two-sided Z tests.

RESULTS

The age-adjusted recall rate was 9.8% in Vermont and 2.7% in Norway (P < .001). The age-adjusted screen detection rate per 1000 woman-years after 2 years of follow-up was 2.77 in Vermont and 2.57 in Norway (P = .12), whereas the interval cancer rate per 1000 woman-years was 1.24 and 0.86, respectively (P < .001). Larger proportions of invasive interval cancers in Vermont than in Norway were 15 mm or smaller (55.9% vs 38.2%, P < .001) and had no lymph node involvement (67.5% vs 57%, P = .01). The prognostic characteristics of all invasive cancers (screen-detected and interval cancer) were similar in Vermont and Norway.

CONCLUSION

Screening mammography detected cancer at about the same rate and at the same prognostic stage in Norway and Vermont, with a statistically significantly lower recall rate in Norway. The interval cancer rate was higher in Vermont than in Norway, but tumors that were diagnosed in the Vermont women tended to be at an earlier stage than those diagnosed in the Norwegian women.

Using the European guidelines to evaluate the Norwegian Breast Cancer Screening Program

This is an evaluation of selected process indicators achieved during the first 10 years of performance of the Norwegian Breast Cancer Screening Program (NBCSP). The indicators are compared with the recommended levels given in the European Guidelines. The program invites all female residents aged 50-69 years old to two-view mammography biennially. The attendance rate was 76.2%. The recall rates due to positive mammography were 4.6% and 2.6%, and the detection rates were 6.4 and 4.9 per 1,000 screens, in prevalent and subsequent screens, respectively. Mean tumor size was 14.7 mm for screening detected and 21.2 mm for interval cancers. Axillary lymph node metastases were present in 25.4% and 43.8%, respectively. Detection mode (screening detected or interval cancer) was shown to be an independent predictor for axillary lymph node metastases and high-grade (Grade 3) tumors. The NBCSP meets the recommendations given in the European Guidelines for most of the process indicators evaluated in this study. Based on the results, we anticipate a future mortality reduction from breast cancer in women invited to the NBCSP.

Randomized trial of screen-film versus full-field digital mammography with soft-copy reading in population-based screening program: follow-up and final results of Oslo II study

PURPOSE

To prospectively compare performance indicators at screen-film mammography (SFM) and full-field digital mammography (FFDM) in a population-based screening program.

MATERIALS AND METHODS

The regional ethics committee approved the study; informed consent was obtained from patients. Women aged 45-69 years were assigned to undergo SFM (n=16 985) or FFDM (n=6944). Two-view mammograms were interpreted by using independent double reading and a five-point rating scale for probability of cancer. Positive scores were discussed at consensus meetings before decision for recall. The group was followed up for 1.5 years (women aged 45-49 years) and 2.0 years (women aged 50-69 years) to include subsequent cancers with positive scores at baseline interpretation and to estimate interval cancer rate. Recall rates, cancer detection, positive predictive values (PPVs), sensitivity, specificity, tumor characteristics, and discordant interpretations of cancers were compared.

RESULTS

Recall rate was 4.2% at FFDM and 2.5% at SFM (P<.001). Cancer detection rate was 0.59% at FFDM and 0.38% at SFM (P=.02). There was no significant difference in PPVs. Median size of screening-detected invasive cancers was 14 mm at FFDM and 13 mm at SFM. Including cancers dismissed at consensus meetings, overall true-positive rate at baseline reading was 0.63% at FFDM and 0.43% at SFM (P=.04). Sensitivity was 77.4% at FFDM and 61.5% at SFM (P=.07); specificity was 96.5% and 97.9%, respectively (P<.005). Interval cancer rate was 17.4 at FFDM and 23.6 at SFM. The proportion of cancers with discordant double readings was comparable at FFDM and SFM.

CONCLUSION

FFDM resulted in a significantly higher cancer detection rate than did SFM. The PPVs were comparable for the two imaging modalities.