Modelling the cumulative risk of a false-positive screening test

Long-term psychosocial consequences of false-positive screening mammography: a cohort study with follow-up of 12-14 years in Denmark

OBJECTIVE

To compare the long-term psychosocial consequences of mammography screening among women with breast cancer, normal results and false-positive results.

DESIGN

A matched cohort study with follow-up of 12-14 years.

SETTING

Denmark from 2004 to 2019.

PARTICIPANTS

1170 women who participated in the Danish mammography screening programme in 2004-2005.

INTERVENTION

Mammography screening for women aged 50-69 years.

OUTCOME MEASURES

We assessed the psychosocial consequences with the Consequences Of Screening-Breast Cancer, a condition-specific questionnaire that is psychometrically validated and encompasses 14 psychosocial dimensions.

RESULTS

Across all 14 psychosocial outcomes, women with false-positive results averagely reported higher psychosocial consequences compared with women with normal findings. Mean differences were statistically insignificant except for the existential values scale: 0.61 (95% CI (0.15 to 1.06), p=0.009). Additionally, women with false-positive results and women diagnosed with breast cancer were affected in a dose-response manner, where women diagnosed with breast cancer were more affected than women with false-positive results.

CONCLUSION

Our study suggests that a false-positive mammogram is associated with increased psychosocial consequences 12-14 years after the screening. This study adds to the harms of mammography screening. The findings should be used to inform decision-making among the invited women and political and governmental decisions about mammography screening programmes.

Cumulative Advanced Breast Cancer Risk Prediction Model Developed in a Screening Mammography Population

BACKGROUND

Estimating advanced breast cancer risk in women undergoing annual or biennial mammography could identify women who may benefit from less or more intensive screening. We developed an actionable model to predict cumulative 6-year advanced cancer (prognostic pathologic stage II or higher) risk according to screening interval.

METHODS

We included 931 186 women aged 40-74 years in the Breast Cancer Surveillance Consortium undergoing 2 542 382 annual (prior mammogram within 11-18 months) or 752 049 biennial (prior within 19-30 months) screening mammograms. The prediction model includes age, race and ethnicity, body mass index, breast density, family history of breast cancer, and prior breast biopsy subdivided by menopausal status and screening interval. We used fivefold cross-validation to internally validate model performance. We defined higher than 95th percentile as high risk (>0.658%), higher than 75th percentile to 95th or less percentile as intermediate risk (0.380%-0.658%), and 75th or less percentile as low to average risk (<0.380%).

RESULTS

Obesity, high breast density, and proliferative disease with atypia were strongly associated with advanced cancer. The model is well calibrated and has an area under the receiver operating characteristics curve of 0.682 (95% confidence interval = 0.670 to 0.694). Based on women's predicted advanced cancer risk under annual and biennial screening, 69.1% had low or average risk regardless of screening interval, 12.4% intermediate risk with biennial screening and average risk with annual screening, and 17.4% intermediate or high risk regardless of screening interval.

CONCLUSION

Most women have low or average advanced cancer risk and can undergo biennial screening. Intermediate-risk women may consider annual screening, and high-risk women may consider supplemental imaging in addition to annual screening.

Benefits and harms of annual, biennial, or triennial breast cancer mammography screening for women at average risk of breast cancer: a systematic review for the European Commission Initiative on Breast Cancer (ECIBC)

BACKGROUND

Although mammography screening is recommended in most European countries, the balance between the benefits and harms of different screening intervals is still a matter of debate. This review informed the European Commission Initiative on Breast Cancer (BC) recommendations.

METHODS

We searched PubMed, EMBASE, and the Cochrane Library to identify RCTs, observational or modelling studies, comparing desirable (BC deaths averted, QALYs, BC stage, interval cancer) and undesirable (overdiagnosis, false positive related, radiation related) effects from annual, biennial, or triennial mammography screening in women of average risk for BC. We assessed the certainty of the evidence using the GRADE approach.

RESULTS

We included one RCT, 13 observational, and 11 modelling studies. In women 50-69, annual compared to biennial screening may have small additional benefits but an important increase in false positive results; triennial compared to biennial screening may have smaller benefits while avoiding some harms. In younger women (aged 45-49), annual compared to biennial screening had a smaller gain in benefits and larger harms, showing a less favourable balance in this age group than in women 50-69. In women 70-74, there were fewer additional harms and similar benefits with shorter screening intervals. The overall certainty of the evidence for each of these comparisons was very low.

CONCLUSIONS

In women of average BC risk, screening intervals have different trade-offs for each age group. The balance probably favours biennial screening in women 50-69. In younger women, annual screening may have a less favourable balance, while in women aged 70-74 years longer screening intervals may be more favourable.

Cumulative Probability of False-Positive Results After 10 Years of Screening With Digital Breast Tomosynthesis vs Digital Mammography

Importance

Breast cancer screening with digital breast tomosynthesis may decrease false-positive results compared with digital mammography.

Objective

To estimate the probability of receiving at least 1 false-positive result after 10 years of screening with digital breast tomosynthesis vs digital mammography in the US.

Design, Setting, and Participants

An observational comparative effectiveness study with data collected prospectively for screening examinations was performed between January 1, 2005, and December 31, 2018, at 126 radiology facilities in the Breast Cancer Surveillance Consortium. Analysis included 903 495 individuals aged 40 to 79 years. Data analysis was conducted from February 9 to September 7, 2021.

Exposures

Screening modality, screening interval, age, and Breast Imaging Reporting and Data System breast density.

Main Outcomes and Measures

Cumulative risk of at least 1 false-positive recall for further imaging, short-interval follow-up recommendation, and biopsy recommendation after 10 years of annual or biennial screening with digital breast tomosynthesis vs digital mammography, accounting for competing risks of breast cancer diagnosis and death.

Results

In this study of 903 495 women, 2 969 055 nonbaseline screening examinations were performed with interpretation by 699 radiologists. Mean (SD) age of the women at the time of the screening examinations was 57.6 (9.9) years, and 58% of the examinations were in individuals younger than 60 years and 46% were performed in women with dense breasts. A total of 15% of examinations used tomosynthesis. For annual screening, the 10-year cumulative probability of at least 1 false-positive result was significantly lower with tomosynthesis vs digital mammography for all outcomes: 49.6% vs 56.3% (difference, -6.7; 95% CI, -7.4 to -6.1) for recall, 16.6% vs 17.8% (difference, -1.1; 95% CI, -1.7 to -0.6) for short-interval follow-up recommendation, and 11.2% vs 11.7% (difference, -0.5; 95% CI, -1.0 to -0.1) for biopsy recommendation. For biennial screening, the cumulative probability of a false-positive recall was significantly lower for tomosynthesis vs digital mammography (35.7% vs 38.1%; difference, -2.4; 95% CI, -3.4 to -1.5), but cumulative probabilities did not differ significantly by modality for short-interval follow-up recommendation (10.3% vs 10.5%; difference, -0.1; 95% CI, -0.7 to 0.5) or biopsy recommendation (6.6% vs 6.7%; difference, -0.1; 95% CI, -0.5 to 0.4). Decreases in cumulative probabilities of false-positive results with tomosynthesis vs digital mammography were largest for annual screening in women with nondense breasts (differences for recall, -6.5 to -12.8; short-interval follow-up, 0.1 to -5.2; and biopsy recommendation, -0.5 to -3.1). Regardless of modality, cumulative probabilities of false-positive results were substantially lower for biennial vs annual screening (overall recall, 35.7 to 38.1 vs 49.6 to 56.3; short-interval follow-up, 10.3 to 10.5 vs 16.6 to 17.8; and biopsy recommendation, 6.6 to 6.7 vs 11.2 to 11.7); older vs younger age groups (eg, among annual screening in women ages 70-79 vs 40-49, recall, 39.8 to 47.0 vs 60.8 to 68.0; short-interval follow-up, 13.3 to 14.2 vs 20.7 to 20.9; and biopsy recommendation, 9.1 to 9.3 vs 13.2 to 13.4); and women with entirely fatty vs extremely dense breasts (eg, among annual screening in women aged 50-59 years, recall, 29.1 to 36.3 vs 58.8 to 60.4; short-interval follow-up, 8.9 to 11.6 vs 19.5 to 19.8; and biopsy recommendation, 4.9 to 8.0 vs 15.1 to 15.3).

Conclusions and Relevance

In this comparative effectiveness study, 10-year cumulative probabilities of false-positive results were lower on digital breast tomosynthesis vs digital mammography. Biennial screening interval, older age, and nondense breasts were associated with larger reductions in false-positive probabilities than screening modality.

Nonhomogeneous Markov chain for estimating the cumulative risk of multiple false positive screening tests

Screening tests are widely recommended for the early detection of disease among asymptomatic individuals. While detecting disease at an earlier stage has the potential to improve outcomes, screening also has negative consequences, including false positive results which may lead to anxiety, unnecessary diagnostic procedures, and increased healthcare costs. In addition, multiple false positive results could discourage participating in subsequent screening rounds. Screening guidelines typically recommend repeated screening over a period of many years, but little prior research has investigated how often individuals receive multiple false positive test results. Estimating the cumulative risk of multiple false positive results over the course of multiple rounds of screening is challenging due to the presence of censoring and competing risks, which may depend on the false positive risk, screening round, and number of prior false positive results. To address the general challenge of estimating the cumulative risk of multiple false positive test results, we propose a nonhomogeneous multistate model to describe the screening process including competing events. We developed alternative approaches for estimating the cumulative risk of multiple false positive results using this multistate model based on existing estimators for the cumulative risk of a single false positive. We compared the performance of the newly proposed models through simulation studies and illustrate model performance using data on screening mammography from the Breast Cancer Surveillance Consortium. Across most simulation scenarios, the multistate extension of a censoring bias model demonstrated lower bias compared to other approaches. In the context of screening mammography, we found that the cumulative risk of multiple false positive results is high. For instance, based on the censoring bias model, for a high-risk individual, the cumulative probability of at least two false positive mammography results after 10 rounds of annual screening is 40.4.

False-Positive Results in a Population-Based Colorectal Screening Program: Cumulative Risk from 2000 to 2017 with Biennial Screening

BACKGROUND

The aim of this study was to estimate the cumulative risk of a false-positive (FP) result in a fecal occult blood test (FOBT) through 7 screening rounds and to identify its associated factors in a population-based colorectal cancer screening program.

METHODS

Retrospective cohort study, which included participants ages 50 to 69 years of a colorectal cancer screening program in Catalonia, Spain. During this period, 2 FOBTs were used (guaiac and immunochemical). A discrete-time survival model was performed to identify risk factors of receiving a positive FOBT with no high-risk adenoma or colorectal cancer in the follow-up colonoscopy. We estimated the probability of having at least 1 FP over 7 screening rounds.

RESULTS

During the period of 2000 to 2017, the cumulative FP risk was 16.3% (IC_95%: 14.6%-18.3%), adjusted by age, sex, and type of test. The median number of screens was 2. Participants who began screening at age 50 years had a 7.3% [95% confidence interval (CI), 6.35-8.51] and a 12.4% (95% CI, 11.00-13.94) probability of an FP with 4 screening rounds of guaiac-based test and immunochemical test, respectively. Age, the fecal immunochemical test, first screening, and number of personal screens were factors associated with an FP result among screenees.

CONCLUSIONS

The cumulative risk of an FP in colorectal screening using FOBT seems acceptable as the colonoscopy, with its high accuracy, lengthens the time until additional colorectal screening is required, while complication rates remain low.

IMPACT

It is useful to determine the cumulative FP risk in cancer screening for both advising individuals and for health resources planning.

The impact of different prostate-specific antigen (PSA) testing intervals on Gleason score at diagnosis and the risk of experiencing false-positive biopsy recommendations: a population-based cohort study

OBJECTIVE

Given a man's current prostate- specific antigen (PSA) level, age and family history of prostate cancer, what are the benefits (decreased risk of higher Gleason score [GS] cancer at diagnosis) and harms (increased risk of false-positive biopsy recommendation) of waiting 1, 2, 3, 4 or 5-8 years until the next PSA test?

DESIGN

Prospective cohort.

SETTING

All PSA tested men in Stockholm, Sweden, between 2003 and 2015.

PARTICIPANTS

Men aged 50-74 years with at least two PSA tests between 2003 and 2015 (n=174 636).

MAIN OUTCOME MEASURES

Log-binomial regression to calculate the risk ratio (RR) of GS ≥7 and GS 6 versus benign outcome at prostate biopsy and 12-year cumulative probability of experiencing a false-positive biopsy by testing interval, age, PSA level and first-degree family history.

RESULTS

Men with PSA ≤1 ng/mL had low risk of GS ≥7 prostate cancer irrespective of testing interval; <3% had a PSA >3 at the next testing occasion, and of the 663 men biopsied after the next PSA test only 32 (5%) had GS ≥7 cancer. Men with PSA >1 ng/mL had increased risk of being diagnosed with GS ≥7 prostate cancer when screened with longer than annual intervals (RRs ranged from 1.4 to 3.2 depending on PSA level and testing interval). The results were consistent across age groups and family history status. This benefit needs to be balanced against the increased risk for false-positive biopsy recommendation with shorter testing intervals (twofold for annual vs biennial and threefold for annual vs triennial).

CONCLUSIONS

Men aged 50-74 years with PSA ≤1 ng/mL can wait 3-4 years before having a new PSA test. For men with PSA >1 ng/mL, we observed an increased risk of being diagnosed with GS ≥7 prostate cancer with longer than annual testing intervals. This benefit needs to be balanced against the markedly increased risks for false-positive biopsy recommendations with shorter testing intervals recommendations.

Long-term risk of screen-detected and interval breast cancer after false-positive results at mammography screening: joint analysis of three national cohorts

BACKGROUND

We assessed the long-term risk of screen-detected and interval breast cancer in women with a first or second false-positive screening result.

METHODS

Joint analysis had been performed using individual-level data from three population-based screening programs in Europe (Copenhagen in Denmark, Norway, and Spain). Overall, 75,513 screened women aged 50-69 years from Denmark (1991-2010), 556,640 from Norway (1996-2008), and 517,314 from Spain (1994-2010) were included. We used partly conditional Cox hazards models to assess the association between false-positive results and the risk of subsequent screen-detected and interval cancer.

RESULTS

During follow-up, 1,149,467 women underwent 3,510,450 screening exams, and 10,623 screen-detected and 5700 interval cancers were diagnosed. Compared to women with negative tests, those with false-positive results had a two-fold risk of screen-detected (HR = 2.04, 95% CI: 1.93-2.16) and interval cancer (HR = 2.18, 95% CI: 2.02-2.34). Women with a second false-positive result had over a four-fold risk of screen-detected and interval cancer (HR = 4.71, 95% CI: 3.81-5.83 and HR = 4.22, 95% CI: 3.27-5.46, respectively). Women remained at an elevated risk for 12 years after the false-positive result.

CONCLUSIONS

Women with prior false-positive results had an increased risk of screen-detected and interval cancer for over a decade. This information should be considered to design personalised screening strategies based on individual risk.

Consequences of a false-positive mammography result: drug consumption before and after screening

Background Previous research showed women experiencing false-positive mammograms to have greater anxiety about breast cancer than women with normal mammograms. To elucidate psychological effects of false-positive mammograms, we studied impact on drug intake. Methods We calculated the ratio of drug use for women with false-positive versus women with normal mammograms, before and after the event, using population-based registers, 1997-2006. The ratio of the ratios (RRR) assessed the impact. Results Before the test, 40.3% of women from the false-positive group versus 36.2% from the normal group used anxiolytic and antidepressant drugs. There was no difference in use of beta blockers. Hormone therapy was used more frequently by the false-positive, 36.6% versus 28.7%. The proportion of women using anxiolytic and antidepressant drugs increased with 19% from the before to the after period in the false-positive group, and with 16% in the normal group, resulting in an RRR of 1.02 (95% CI 0.92-1.14). RRR was 1.03 for beta blockers, 0.97 for hormone therapy. Conclusion(s) Drugs used to mitigate mood disorders were used more frequently by women with false-positive than by women with normal mammograms already before the screening event, while the changes from before to after screening were similar for both groups. The results point to the importance of control for potential selection in studies of screening effects.

Radiation-Induced Breast Cancer Incidence and Mortality From Digital Mammography Screening: A Modeling Study

BACKGROUND

Estimates of risk for radiation-induced breast cancer from mammography screening have not considered variation in dose exposure or diagnostic work-up after abnormal screening results.

OBJECTIVE

To estimate distributions of radiation-induced breast cancer incidence and mortality from digital mammography screening while considering exposure from screening and diagnostic mammography and dose variation among women.

DESIGN

2 simulation-modeling approaches.

SETTING

U.S. population.

PATIENTS

Women aged 40 to 74 years.

INTERVENTION

Annual or biennial digital mammography screening from age 40, 45, or 50 years until age 74 years.

MEASUREMENTS

Lifetime breast cancer deaths averted (benefits) and radiation-induced breast cancer incidence and mortality (harms) per 100,000 women screened.

RESULTS

Annual screening of 100,000 women aged 40 to 74 years was projected to induce 125 breast cancer cases (95% CI, 88 to 178) leading to 16 deaths (CI, 11 to 23), relative to 968 breast cancer deaths averted by early detection from screening. Women exposed at the 95th percentile were projected to develop 246 cases of radiation-induced breast cancer leading to 32 deaths per 100,000 women. Women with large breasts requiring extra views for complete examination (8% of population) were projected to have greater radiation-induced breast cancer risk (266 cancer cases and 35 deaths per 100,000 women) than other women (113 cancer cases and 15 deaths per 100,000 women). Biennial screening starting at age 50 years reduced risk for radiation-induced cancer 5-fold.

LIMITATION

Life-years lost from radiation-induced breast cancer could not be estimated.

CONCLUSION

Radiation-induced breast cancer incidence and mortality from digital mammography screening are affected by dose variability from screening, resultant diagnostic work-up, initiation age, and screening frequency. Women with large breasts may have a greater risk for radiation-induced breast cancer.

PRIMARY FUNDING SOURCE

Agency for Healthcare Research and Quality, U.S. Preventive Services Task Force, National Cancer Institute.

Factors Associated With Rates of False-Positive and False-Negative Results From Digital Mammography Screening: An Analysis of Registry Data

BACKGROUND

Women screened with digital mammography may receive false-positive and false-negative results and subsequent imaging and biopsies. How these outcomes vary by age, time since the last screening, and individual risk factors is unclear.

OBJECTIVE

To determine factors associated with false-positive and false-negative digital mammography results, additional imaging, and biopsies among a general population of women screened for breast cancer.

DESIGN

Analysis of registry data.

SETTING

Participating facilities at 5 U.S. Breast Cancer Surveillance Consortium breast imaging registries with linkages to pathology databases and tumor registries.

PATIENTS

405,191 women aged 40 to 89 years screened with digital mammography between 2003 and 2011. A total of 2963 were diagnosed with invasive cancer or ductal carcinoma in situ within 12 months of screening.

MEASUREMENTS

Rates of false-positive and false-negative results and recommendations for additional imaging and biopsies from a single screening round; comparisons by age, time since the last screening, and risk factors.

RESULTS

Rates of false-positive results (121.2 per 1000 women [95% CI, 105.6 to 138.7]) and recommendations for additional imaging (124.9 per 1000 women [CI, 109.3 to 142.3]) were highest among women aged 40 to 49 years and decreased with increasing age. Rates of false-negative results (1.0 to 1.5 per 1000 women) and recommendations for biopsy (15.6 to 17.5 per 1000 women) did not differ greatly by age. Results did not differ by time since the last screening. False-positive rates were higher for women with risk factors, particularly family history of breast cancer; previous benign breast biopsy result; high breast density; and, for younger women, low body mass index.

LIMITATIONS

Confounding by variation in patient-level characteristics and outcomes across registries and regions may have been present. Some factors, such as numbers of first- and second-degree relatives with breast cancer and diagnoses associated with previous benign biopsy results, were not examined.

CONCLUSION

False-positive mammography results and additional imaging are common, particularly for younger women and those with risk factors, whereas biopsies occur less often. Rates of false-negative results are low.

PRIMARY FUNDING SOURCE

Agency for Healthcare Research and Quality and National Cancer Institute.

Statistical Methods for Estimating the Cumulative Risk of Screening Mammography Outcomes

BACKGROUND

This study illustrates alternative statistical methods for estimating cumulative risk of screening mammography outcomes in longitudinal studies.

METHODS

Data from the US Breast Cancer Surveillance Consortium (BCSC) and the Nijmegen Breast Cancer Screening Program in the Netherlands were used to compare four statistical approaches to estimating cumulative risk. We estimated cumulative risk of false-positive recall and screen-detected cancer after 10 screening rounds using data from 242,835 women ages 40 to 74 years screened at the BCSC facilities in 1993-2012 and from 17,297 women ages 50 to 74 years screened in Nijmegen in 1990-2012.

RESULTS

In the BCSC cohort, a censoring bias model estimated bounds of 53.8% to 59.3% for false-positive recall and 2.4% to 7.6% for screen-detected cancer, assuming 10% increased or decreased risk among women screened for one additional round. In the Nijmegen cohort, false-positive recall appeared to be associated with subsequent discontinuation of screening leading to overestimation of risk of a false-positive recall based on adjusted discrete-time survival models. Bounds estimated by the censoring bias model were 11.0% to 19.9% for false-positive recall and 4.2% to 9.7% for screen-detected cancer.

CONCLUSION

Choice of statistical methodology can substantially affect cumulative risk estimates. The censoring bias model is appropriate under a variety of censoring mechanisms and provides bounds for cumulative risk estimates under varying degrees of dependent censoring.

IMPACT

This article illustrates statistical methods for estimating cumulative risks of cancer screening outcomes, which will be increasingly important as screening test recommendations proliferate.

Towards personalized screening: Cumulative risk of breast cancer screening outcomes in women with and without a first-degree relative with a history of breast cancer

Several reviews have estimated the balance of benefits and harms of mammographic screening in the general population. The balance may, however, differ between individuals with and without family history. Therefore, our aim is to assess the cumulative risk of screening outcomes; screen-detected breast cancer, interval cancer, and false-positive results, in women screenees aged 50-75 and 40-75, with and without a first-degree relative with a history of breast cancer at the start of screening. Data on screening attendance, recall and breast cancer detection were collected for each woman living in Nijmegen (The Netherlands) since 1975. We used a discrete time survival model to calculate the cumulative probability of each major screening outcome over 19 screening rounds. Women with a family history of breast cancer had a higher risk of all screening outcomes. For women screened from age 50-75, the cumulative risk of screen-detected breast cancer, interval cancer and false-positive results were 9.0, 4.4 and 11.1% for women with a family history and 6.3, 2.7 and 7.3% for women without a family history, respectively. The results for women 40-75 followed the same pattern for women screened 50-75 for cancer outcomes, but were almost doubled for false-positive results. To conclude, women with a first-degree relative with a history of breast cancer are more likely to experience benefits and harms of screening than women without a family history. To complete the balance and provide risk-based screening recommendations, the breast cancer mortality reduction and overdiagnosis should be estimated for family history subgroups.

Comparison of cumulative false-positive risk of screening mammography in the United States and Denmark

INTRODUCTION

In the United States (US), about one-half of women screened with annual mammography have at least one false-positive test after ten screens. The estimate for European women screened ten times biennially is much lower. We evaluate to what extent screening interval, mammogram type, and statistical methods, can explain the reported differences.

METHODS

We included all screens from women first screened at age 50-69 years in the US Breast Cancer Surveillance Consortium (BCSC) (n=99,455) between 1996-2010, and from two population-based mammography screening programs in Denmark (n=230,452 and n=400,204), between 1991-2012 and 1993-2013, respectively. Model-based cumulative false-positive risks were computed for the entire sample, using two statistical methods (Hubbard Njor) previously used to estimate false-positive risks in the US and Europe.

RESULTS

Empirical cumulative risk of at least one false-positive test after eight (annual or biennial) screens was 41.9% in BCSC, 16.1% in Copenhagen, and 7.4% in Funen. Variation in screening interval and mammogram type did not explain the differences by country. Using the Hubbard method, the model-based cumulative risks after eight screens was 45.1% in BCSC, 9.6% in Copenhagen, and 8.8% in Funen. Using the Njor method, these risks were estimated to be 43.6, 10.9 and 8.0%.

CONCLUSION

Choice of statistical method, screening interval and mammogram type does not explain the substantial differences in cumulative false-positive risk between the US and Europe.

The cumulative risk of false-positive screening results across screening centres in the Norwegian Breast Cancer Screening Program

BACKGROUND

Recall for assessment in mammographic screening entails an inevitable number of false-positive screening results. This study aimed to investigate the variation in the cumulative risk of a false positive screening result and the positive predictive value across the screening centres in the Norwegian Breast Cancer Screening Program.

METHODS

We studied 618,636 women aged 50-69 years who underwent 2,090,575 screening exams (1996-2010. Recall rate, positive predictive value, rate of screen-detected cancer, and the cumulative risk of a false positive screening result, without and with invasive procedures across the screening centres were calculated. Generalized linear models were used to estimate the probability of a false positive screening result and to compute the cumulative false-positive risk for up to ten biennial screening examinations.

RESULTS

The cumulative risk of a false-positive screening exam varied from 10.7% (95% CI: 9.4-12.0%) to 41.5% (95% CI: 34.1-48.9%) across screening centres, with a highest to lowest ratio of 3.9 (95% CI: 3.7-4.0). The highest to lowest ratio for the cumulative risk of undergoing an invasive procedure with a benign outcome was 4.3 (95% CI: 4.0-4.6). The positive predictive value of recall varied between 12.0% (95% CI: 11.0-12.9%) and 19.9% (95% CI: 18.3-21.5%), with a highest to lowest ratio of 1.7 (95% CI: 1.5-1.9).

CONCLUSIONS

A substantial variation in the performance measures across the screening centres in the Norwegian Breast Cancer Screening Program was identified, despite of similar administration, procedures, and quality assurance requirements. Differences in the readers' performance is probably of influence for the variability. This results underscore the importance of continuous surveillance of the screening centres and the radiologists in order to sustain and improve the performance and effectiveness of screening programs.

The cumulative risk of false-positive results in the Norwegian Breast Cancer Screening Program: updated results

BACKGROUND

Some false-positive results are inevitable in mammographic screening, but the impact of false-positive findings on the program and the participants is a disadvantage of screening. The objective of the current study was to estimate the cumulative risk of a false-positive result over 10 biennial screening examinations and the cumulative risk of undergoing an invasive procedure with a benign outcome in women screened between the ages of 50 years to 69 years.

METHODS

A retrospective cohort study was performed in 231,310 women aged 50 years to 51 years at the time of first mammography screening who underwent 715,311 screening mammograms in the Norwegian Breast Cancer Screening Program from 1996 through 2010. Generalized linear mixed models were used to estimate the probability of a false-positive screening result and to compute the cumulative false-positive risk for up to 10 biennial screening examinations.

RESULTS

The cumulative false-positive risk after 20 years of biennial screening for women who initiated screening aged 50 years to 51 years was 20.0% (95% confidence interval [95% CI], 19.7%-20.4%). The cumulative risk of undergoing an invasive procedure with a benign outcome for the same group of women was 4.1% (95% CI, 3.9%-4.3%). The cumulative risk of undergoing a fine-needle aspiration cytology, core needle biopsy, or open biopsy with a benign outcome was 1.4% (95% CI, 1.3%-1.5%), 2.0% (95% CI, 1.9%-2.1%), and 0.16% (95% CI, 0.13%-0.19%), respectively.

CONCLUSIONS

One in every 5 women will be recalled for further assessment with a negative outcome if they attend biennial mammographic screening between ages 50 years to 69 years. The risk of an invasive procedure with a benign outcome is approximately 4%. It is important to communicate the existence and extent of this risk to the target group and to reduce to a minimum the waiting times between screening and further assessment.

Impact of mammography screening interval on breast cancer diagnosis by menopausal status and BMI

BACKGROUND

Controversy remains regarding the frequency of screening mammography. Women with different risks for developing breast cancer because of body mass index (BMI) may benefit from tailored recommendations.

OBJECTIVE

To determine the impact of mammography screening interval for women who are normal weight (BMI < 25), overweight (BMI 25-29.9), or obese (BMI ≥ 30), stratified by menopausal status.

DESIGN

Two cohorts selected from the Breast Cancer Surveillance Consortium. Patient and mammography data were linked to pathology databases and tumor registries.

PARTICIPANTS

The cohort included 4,432 women aged 40-74 with breast cancer; the false-positive analysis included a cohort of 553,343 women aged 40-74 without breast cancer.

MAIN MEASURES

Stage, tumor size and lymph node status by BMI and screening interval (biennial vs. annual). Cumulative probability of false-positive recall or biopsy by BMI and screening interval. Analyses were stratified by menopausal status.

KEY RESULTS

Premenopausal obese women undergoing biennial screening had a non-significantly increased odds of a tumor size > 20 mm relative to annual screeners (odds ratio [OR] = 2.07; 95 % confidence interval [CI] 0.997 to 4.30). Across all BMI categories from normal to obese, postmenopausal women with breast cancer did not present with higher stage, larger tumor size or node positive tumors if they received biennial rather than annual screening. False-positive recall and biopsy recommendations were more common among annually screened women.

CONCLUSION

The only negative outcome identified for biennial vs. annual screening was a larger tumor size (> 20 mm) among obese premenopausal women. Since annual mammography does not improve stage at diagnosis compared to biennial screening and false-positive recall/biopsy rates are higher with annual screening, women and their primary care providers should weigh the harms and benefits when deciding on annual versus biennial screening.

Mammographic screening interval in relation to tumor characteristics and false-positive risk by race/ethnicity and age

BACKGROUND

Biennial screening mammography retains most of the benefits of annual breast cancer screening with reduced harms. Whether screening guidelines based on race/ethnicity and age would be more effective than age-based guidelines is unknown.

METHODS

Mammography data from the Breast Cancer Surveillance Consortium were linked to pathology and tumor databases. The authors identified women aged 40 to 74 years who underwent annual, biennial, or triennial screening mammography between 1994 and 2008. Logistic regression was used to estimate adjusted odds ratios (OR) and 95% confidence intervals (95% CI) of adverse tumor characteristics among 14,396 incident breast cancer cases and 10-year cumulative risks of false-positive recall and biopsy recommendation among 1,276,312 noncases.

RESULTS

No increased risk of adverse tumor characteristics associated with biennial versus annual screening were noted in white women, black women, Hispanic women aged 40 to 49 years, or Asian women aged 50 to 74 years. Hispanic women aged 50 to 74 years who screened biennially versus annually were found to have an increased risk of late-stage disease (OR, 1.6; 95% CI, 1.0-2.5) and large tumors (OR, 1.6; 95% CI, 1.1-2.4). Asian women aged 40 to 49 years who underwent biennial screening had an elevated risk of positive lymph nodes (OR, 3.1; 95% CI, 1.3-7.1). No elevated risks were associated with triennial versus biennial screening. Cumulative false-positive risks decreased markedly with a longer screening interval.

CONCLUSIONS

The authors found limited evidence of elevated risks of adverse tumor characteristics with biennial versus annual screening, whereas cumulative false-positive risks were lower. However, elevated risks of late-stage disease in Hispanic women and lymph node-positive disease in younger Asian women who screened less often than annually warrant consideration and replication.

Outcomes of screening mammography by frequency, breast density, and postmenopausal hormone therapy

IMPORTANCE

Controversy exists about the frequency women should undergo screening mammography and whether screening interval should vary according to risk factors beyond age.

OBJECTIVE

To compare the benefits and harms of screening mammography frequencies according to age, breast density, and postmenopausal hormone therapy (HT) use.

DESIGN

Prospective cohort.

SETTING

Data collected January 1994 to December 2008 from mammography facilities in community practice that participate in the Breast Cancer Surveillance Consortium (BCSC) mammography registries.

PARTICIPANTS

Data were collected prospectively on 11,474 women with breast cancer and 922,624 without breast cancer who underwent mammography at facilities that participate in the BCSC.

MAIN OUTCOMES AND MEASURES

We used logistic regression to calculate the odds of advanced stage (IIb, III, or IV) and large tumors (>20 mm in diameter) and 10-year cumulative probability of a false-positive mammography result by screening frequency, age, breast density, and HT use. The main predictor was screening mammography interval.

RESULTS

Mammography biennially vs annually for women aged 50 to 74 years does not increase risk of tumors with advanced stage or large size regardless of women's breast density or HT use. Among women aged 40 to 49 years with extremely dense breasts, biennial mammography vs annual is associated with increased risk of advanced-stage cancer (odds ratio [OR], 1.89; 95% CI, 1.06-3.39) and large tumors (OR, 2.39; 95% CI, 1.37-4.18). Cumulative probability of a false-positive mammography result was high among women undergoing annual mammography with extremely dense breasts who were either aged 40 to 49 years (65.5%) or used estrogen plus progestogen (65.8%) and was lower among women aged 50 to 74 years who underwent biennial or triennial mammography with scattered fibroglandular densities (30.7% and 21.9%, respectively) or fatty breasts (17.4% and 12.1%, respectively).

CONCLUSIONS AND RELEVANCE

Women aged 50 to 74 years, even those with high breast density or HT use, who undergo biennial screening mammography have similar risk of advanced-stage disease and lower cumulative risk of false-positive results than those who undergo annual mammography. When deciding whether to undergo mammography, women aged 40 to 49 years who have extremely dense breasts should be informed that annual mammography may minimize their risk of advanced-stage disease but the cumulative risk of false-positive results is high.

A semiparametric censoring bias model for estimating the cumulative risk of a false-positive screening test under dependent censoring

False-positive test results are among the most common harms of screening tests and may lead to more invasive and expensive diagnostic testing procedures. Estimating the cumulative risk of a false-positive screening test result after repeat screening rounds is, therefore, important for evaluating potential screening regimens. Existing estimators of the cumulative false-positive risk are limited by strong assumptions about censoring mechanisms and parametric assumptions about variation in risk across screening rounds. To address these limitations, we propose a semiparametric censoring bias model for cumulative false-positive risk that allows for dependent censoring without specifying a fixed functional form for variation in risk across screening rounds. Simulation studies demonstrated that the censoring bias model performs similarly to existing models under independent censoring and can largely eliminate bias under dependent censoring. We used the existing and newly proposed models to estimate the cumulative false-positive risk and variation in risk as a function of baseline age and family history of breast cancer after 10 years of annual screening mammography using data from the Breast Cancer Surveillance Consortium. Ignoring potential dependent censoring in this context leads to underestimation of the cumulative risk of false-positive results. Models that provide accurate estimates under dependent censoring are critical for providing appropriate information for evaluating screening tests.

Screening outcomes in older US women undergoing multiple mammograms in community practice: does interval, age, or comorbidity score affect tumor characteristics or false positive rates?

Background Uncertainty exists about the appropriate use of screening mammography among older women because comorbid illnesses may diminish the benefit of screening. We examined the risk of adverse tumor characteristics and false positive rates according to screening interval, age, and comorbidity. Methods From January 1999 to December 2006, data were collected prospectively on 2993 older women with breast cancer and 137 949 older women without breast cancer who underwent mammography at facilities that participated in a data linkage between the Breast Cancer Surveillance Consortium and Medicare claims. Women were aged 66 to 89 years at study entry to allow for measurement of 1 year of preexisting illnesses. We used logistic regression analyses to calculate the odds of advanced (IIb, III, IV) stage, large (>20 millimeters) tumors, and 10-year cumulative probability of false-positive mammography by screening frequency (1 vs 2 years), age, and comorbidity score. The comorbidity score was derived using the Klabunde approximation of the Charlson score. All statistical tests were two-sided. Results Adverse tumor characteristics did not differ statistically significantly by comorbidity, age, or interval. Cumulative probability of a false-positive mammography result was higher among annual screeners than biennial screeners irrespective of comorbidity: 48.0% (95% confidence interval [CI] = 46.1% to 49.9%) of annual screeners aged 66 to 74 years had a false-positive result compared with 29.0% (95% CI = 28.1% to 29.9%) of biennial screeners. Conclusion Women aged 66 to 89 years who undergo biennial screening mammography have similar risk of advanced-stage disease and lower cumulative risk of a false-positive recommendation than annual screeners, regardless of comorbidity.

False-positive screening mammograms and biopsies among women participating in a Canadian provincial breast screening program

BACKGROUND

Mammography screening results in false positives that cause anxiety and utilize scarce medical resources for their resolution. Determination of screening recommendations requires knowledge of the population risk of false positives.

METHODS

Data were extracted from the Screening Mammography Program of British Columbia and analyzed to determine the influence of personal factors including age, ethnic group and screening history, and the centre where screening was performed, on the likelihood a new screen would result in a false positive and whether a biopsy was required. The resulting probabilities were combined to provide values for lifetime screening algorithms.

RESULTS

Age, screen sequence number, history of previous abnormal screens and centre where screening was performed were significantly related to the likelihood a new screen would be a false positive. British Columbia women screened biennially between the ages of 50 and 69 have a projected 41% chance of a false-positive screen and a 5.6% risk of a related biopsy, with the best performing centres having rates of 26% and 3%, respectively.

INTERPRETATION

Model projections for BC overall are comparable to other North American estimates. Estimates varied depending upon screening centre attended.

False-positive screening mammograms and biopsies among women participating in a Canadian provincial breast screening program

BACKGROUND

Mammography screening results in false positives that cause anxiety and utilize scarce medical resources for their resolution. Determination of screening recommendations requires knowledge of the population risk of false positives.

METHODS

Data were extracted from the Screening Mammography Program of British Columbia and analyzed to determine the influence of personal factors including age, ethnic group and screening history, and the centre where screening was performed, on the likelihood a new screen would result in a false positive and whether a biopsy was required. The resulting probabilities were combined to provide values for lifetime screening algorithms.

RESULTS

Age, screen sequence number, history of previous abnormal screens and centre where screening was performed were significantly related to the likelihood a new screen would be a false positive. British Columbia women screened biennially between the ages of 50 and 69 have a projected 41% chance of a false-positive screen and a 5.6% risk of a related biopsy, with the best performing centres having rates of 26% and 3%, respectively.

INTERPRETATION

Model projections for BC overall are comparable to other North American estimates. Estimates varied depending upon screening centre attended.

Screening: part 19 of a series on evaluation of scientific publications

BACKGROUND

The early detection of cancer and other diseases is generally considered beneficial, yet there is evidence that in some diseases screening may be of limited benefit. To clarify this issue, we present the statistical principles that underlie screening. Methods We define screening and discuss the conditions for its successful use. We give illustrative examples from among the currently recommended types of screening in Germany and from the recent medical literature, particularly with regard to mammography.

RESULTS

Certain specific conditions must be fulfilled for screening to be beneficial (usually measured by reduced mortality): The screening procedure must be of high quality, and the screening intervals must be well adapted to the distribution of the sojourn time. Alongside its benefits, screening can also cause harm, particularly to the many patients who are given a false positive test result. According to German law, potential participants are entitled to being given all information necessary to make an informed decision about screening.

CONCLUSION

Just like clinical interventions, screening programs should be evaluated before they are introduced or, at the latest, at the time of their introduction.

Long-term benefits of breast screening

SUMMARY A series of prospective randomized controlled trials of breast cancer screening convincingly demonstrated the efficacy of an invitation to mammography to reduce breast cancer deaths. Evaluation efforts since then have focused on the absolute benefit of breast cancer screening overall and in age-specific subgroups, with various measures of benefit versus harm, and an interest in the degree to which improvements in therapy and women’s improved reporting of symptoms have eclipsed some or all of the benefit of detection of occult disease by mammography. In this article we describe the summary measures of the efficacy of mammography demonstrated by the randomized controlled trials, the importance of long-term follow-up to measure the absolute benefit of mammography and the balance of benefits and harms, including the number needed to screen to save one life and overdiagnosis.

Risk of breast cancer after false-positive test results in screening mammography

BACKGROUND

Screening for disease in healthy people inevitably leads to some false-positive tests in disease-free individuals. Normally, women with false-positive screening tests for breast cancer are referred back to routine screening. However, the long-term outcome for women with false-positive tests is unknown.

METHODS

We used data from a long-standing population-based screening mammography program in Copenhagen, Denmark, to determine the long-term risk of breast cancer in women with false-positive tests. The age-adjusted relative risk (RR) of breast cancer for women with a false-positive test compared with women with only negative tests was estimated with Poisson regression, adjusted for age, and stratified by screening round and technology period. All statistical tests were two-sided.

RESULTS

A total of 58 003 women, aged 50-69 years, were included in the analysis. Women with negative tests had an absolute cancer rate of 339/100 000 person-years at risk, whereas women with a false-positive test had an absolute rate of 583/100 000 person-years at risk. The adjusted relative risk of breast cancer after a false-positive test was 1.67 (95% confidence interval [CI] 1.45 to 1.88). The relative risk remained statistically significantly increased 6 or more years after the false-positive test, with point estimates varying between 1.58 and 2.30. When stratified by assessment technology phase and using equal follow-up time, the false-positive group from the mid 1990s had a statistically significantly higher risk of breast cancer (RR = 1.65, 95% CI = 1.22 to 2.24) than the group with negative tests, whereas the false-positive group from the early 2000s was not statistically significantly different from the group testing negative.

CONCLUSIONS

The implementation of new assessment technology coincided with a decrease in the size of excess risk of breast cancer for women with false-positive screening results. However, it may be beneficial to actively encourage women with false-positive tests to continue to attend regular screening.

Influence of false-positive mammography results on subsequent screening: do physician recommendations buffer negative effects?

OBJECTIVE

Cancer screening guidelines often include discussion about the unintended negative consequences of routine screening. This prospective study examined effects of false-positive mammography results on women's adherence to subsequent breast cancer screening and psychological well-being. We also assessed whether barriers to screening exacerbated the effects of false-positive results.

METHODS

We conducted secondary analyses of data from telephone interviews and medical claims records for 2406 insured women. The primary outcome was adherence to screening guidelines, defined as adherent (10-14 months), delayed (15-34 months), or no subsequent mammogram on record.

RESULTS

About 8% of women reported that their most recent screening mammograms produced false-positive results. In the absence of self-reported advice from their physicians to be screened, women were more likely to have no subsequent mammograms on record if they received false-positive results than if they received normal results (18% vs. 7%, OR = 3.17, 95% CI = 1.30, 7.70). Receipt of false-positive results was not associated with this outcome for women who said their physicians had advised regular screening in the past year (7% vs. 10%, OR = 0.74, 95% CI = 0.38, 1.45). False-positive results were associated with greater breast cancer worry (P < .01), thinking more about the benefits of screening (P < .001), and belief that abnormal test results do not mean women have cancer (P < .01), regardless of physicians' screening recommendations.

CONCLUSION

False-positive mammography results, coupled with reports that women's physicians did not advise regular screening, could lead to non-adherence to future screening. Abnormal mammograms that do not result in cancer diagnoses are opportunities for physicians to stress the importance of regular screening.

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.

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.

The evidence base for breast cancer screening

The history of breast cancer screening is littered with controversy. With 10 trials spanning 4 decades, we have a substantial body of evidence, but with different aims and flaws. Combined analysis of the intention-to-treat results gives an overall relative reduction in breast cancer mortality of 19% (95% CI 12%-26%), which, if adjusted for non-attendance gives an approximate 25% relative reduction for those who attend screening. However, given that 4% of all-cause mortality is due to breast cancer deaths, this translates into a less than 1% reduction in all-cause mortality. An emerging issue in interpretation is the improvements in treatment since these trials recruited women. Modern systemic therapy would have improved survival (models suggest between 12% and 21%) in both screened and non-screened groups, which would result in a lesser difference in absolute risk reduction from screening but probably a similar, or slightly smaller, relative risk reduction. However benefits and harms, particularly over-diagnosis, need to balanced and differ by age-groups. The informed views of recipients of screening are needed to guide current and future policy on screening.