Service screening mammography reduces breast cancer mortality among elderly women in Turku

Worldwide Review and Meta-Analysis of Cohort Studies Measuring the Effect of Mammography Screening Programmes on Incidence-Based Breast Cancer Mortality

In 2012, the Euroscreen project published a review of incidence-based mortality evaluations of breast cancer screening programmes. In this paper, we update this review to October 2019 and expand its scope from Europe to worldwide. We carried out a systematic review of incidence-based mortality studies of breast cancer screening programmes, and a meta-analysis of the estimated effects of both invitation to screening and attendance at screening, with adjustment for self-selection bias, on incidence-based mortality from breast cancer. We found 27 valid studies. The results of the meta-analysis showed a significant 22% reduction in breast cancer mortality with invitation to screening, with a relative risk of 0.78 (95% CI 0.75-0.82), and a significant 33% reduction with actual attendance at screening (RR 0.67, 95% CI 0.61-0.75). Breast cancer screening in the routine healthcare setting continues to confer a substantial reduction in mortality from breast cancer.

Evidence for reducing cancer-specific mortality due to screening for breast cancer in Europe: A systematic review

BACKGROUND

The aim of this study was to quantify the impact of organised mammography screening on breast cancer mortality across European regions. Therefore, a systematic review was performed including different types of studies from all European regions and stringently used clearly defined quality appraisal to summarise the best evidence.

METHODS

Six databases were searched including Embase, Medline and Web of Science from inception to March 2018. To identify all eligible studies which assessed the effect of organised screening on breast cancer mortality, two reviewers independently applied predefined inclusion and exclusion criteria. Original studies in English with a minimum follow-up of five years that were randomised controlled trials (RCTs) or observational studies were included. The Cochrane risk of bias instrument and the Newcastle-Ottawa Scale were used to assess the risk of bias.

RESULTS

Of the 5015 references initially retrieved, 60 were included in the final analysis. Those comprised 36 cohort studies, 17 case-control studies and 7 RCTs. None were from Eastern Europe. The quality of the included studies varied: Nineteen of these studies were of very good or good quality. Of those, the reduction in breast cancer mortality in attenders versus non-attenders ranged between 33% and 43% (Northern Europe), 43%-45% (Southern Europe) and 12%-58% (Western Europe). The estimates ranged between 4% and 31% in invited versus non-invited.

CONCLUSION

This systematic review provides evidence that organised screening reduces breast cancer mortality in all European regions where screening was implemented and monitored, while quantification is still lacking for Eastern Europe. The wide range of estimates indicates large differences in the evaluation designs between studies, rather than in the effectiveness of screening.

Mammography service screening and breast cancer mortality in New Zealand: a National Cohort Study 1999-2011

Background:

This breast cancer mortality evaluation of service screening mammography in New Zealand, the first since commencement of screening in 1999, applies to the 1999–2011 diagnostic period. Individual-level linked information on mammography screening, breast cancer diagnosis and breast cancer mortality is used to analyse differences in breast cancer mortality according to participation in organised screening mammography, as provided by BreastScreen Aotearoa (BSA).

Methods:

Women were followed from the time they became eligible for screening, from age 50 years (1999–2004) and 45 years (⩾2004). Breast cancer mortality from cancers diagnosed during the screening period from 1999 to 2011 (n=4384) is examined in relation to individual screening participation or non-participation during preceding person-years of follow-up from the time of screening eligibility. To account for changes from never- to ever-screened status, breast cancer mortality is calculated for each year in relation to prior accumulated time of participation and non-participation in screening. Breast cancer mortality is also examined in regularly screened women (screened ⩾3 times and mean screening interval ⩽30 months), and irregularly screened women compared with never-screened women. Statistical analyses are by negative binomial and Poisson regression with adjustment for age and ethnic group (Māori, Pacific women) in a repeated-measures analysis. Relative risks for breast cancer mortality compared with never-screened women, are adjusted also for screening selection bias, to indicate the extent of breast cancer mortality reduction in a population offered and not offered mammography screening. Prognostic indicators at diagnosis of breast cancer are also compared between different screening participation groups, including by grade of tumour, extent of disease (spread), multiple tumour status and maximum tumour size using χ² statistics, t-tests and two-sample median tests.

Results:

For 1999–2011, after adjusting for age and ethnicity, breast cancer mortality in ever-screened women is estimated to be 62% (95% CI: 51–70) lower than in never-screened women. After further adjustment for screening selection bias, the mortality reduction in NZ is estimated to be 29% (95% CI: 20–38) at an average screening coverage of 64% for 2001–2011, and 34% (95% CI: 25–43) for recent screening coverage (2012–13, 71%). For irregularly screened women, the mortality reduction is estimated to be 31% (95% CI: 21–40), and 39% (95% CI: 22–52) in regularly screened women compared with never-screened women, after adjusting for age, ethnicity and screening selection bias (using recent 2012–2013 screening coverage of 71%). Ever-screened women diagnosed with breast cancer have more favourable prognostic indicators than never-screened women, with a higher proportion of localised cancer (63 compared with 46%), a higher proportion with a well-differentiated tumour (30 compared with 18%), lower risk of multiple tumours (RR=0.48) and smaller median tumour size (15 mm compared with 20 mm)—all differences are statistically significant (P<0.0001).

Conclusions:

This is the first total population cohort study of an established nation-wide screening mammography programme using individual-level information on screening participation and mortality outcomes from breast cancer. The findings are in accord with other mammography screening service evaluations and with randomised trials of mammography screening.

Mammography screening in three Finnish residential areas: comprehensive population-based study of breast cancer incidence and incidence-based mortality 1976-2009

BACKGROUND

The aim of this study was to evaluate the effectiveness of a large-scale screening programme for breast cancer (BC) in Turku, Finland. Incidence and incidence-based mortality (IBM) figures were compared with the areas applying different screening policies.

METHODS

Deaths and person-time of women aged 40-84 were assessed for the period 1976-1986 (prescreening era) and the periods 1987-1997 and 1998-2009 (screening periods) using incidence and IBM by age at diagnosis and at death. There was a total of 40.7 million women-years, 83 497 invasive BCs obtained from the Finnish Cancer Registry; 17 508 BC deaths were linked with the data from Statistics Finland.

RESULTS

In Turku, a significant (> 20%) reduction in IBM occurred during 1987-2009 among women aged 60-74 years at diagnosis compared with Helsinki (IBMRR: 0.75, 95% CI: 0.57-1.00), and in women aged 75-84 years at death compared with the rest of Finland (IBMRR: 0.72, 95% CI: 0.53-0.96).

CONCLUSIONS

The wide mammography screening programme in Turku was effective in decreasing BC mortality in the elderly age groups. These results support the implementation of BC screening from age 50 up to 74 years.

Mammography interval and breast cancer mortality in women over the age of 75

The purpose of this study is to evaluate the relationship between mammography interval and breast cancer mortality among older women with breast cancer. The study population included 1,914 women diagnosed with invasive breast cancer at age 75 or later during their participation in the Women's health initiative, with an average follow-up of 4.4 years (3.1 SD). Cause of death was based on medical record review. Mammography interval was defined as the time between the last self-reported mammogram 7 or more months prior to diagnosis, and the date of diagnosis. Multivariable adjusted hazard ratios (HR) and 95 % confidence intervals (CIs) for breast cancer mortality and all-cause mortality were computed from Cox proportional hazards analyses. Prior mammograms were reported by 73.0 % of women from 7 months to ≤2 year of diagnosis (referent group), 19.4 % (>2 to <5 years), and 7.5 % (≥5 years or no prior mammogram). Women with the longest versus shortest intervals had more poorly differentiated (28.5 % vs. 22.7 %), advanced stage (25.7 % vs. 22.9 %), and estrogen receptor negative tumors (20.9 % vs. 13.1 %). Compared to the referent group, women with intervals of >2 to <5 years or ≥5 years had an increased risk of breast cancer mortality (HR 1.62, 95 % CI 1.03-2.54) and (HR 2.80, 95 % CI 1.57-5.00), respectively, p trend = 0.0002. There was no significant relationship between mammography interval and other causes of death. These results suggest a continued role for screening mammography among women 75 years of age and older.

[Assessment of screening in women cancers and in 75 years older in Loire department]

In France, there is an important interregional disparity concerning participation to cancer screening programs. The aim of this study was to assess oncologic screening practices in Loire, a French rural department, in women and in the elderly (over age 74 years). For this, two surveys were conducted. The first one was regarding screening for breast, cervical and colorectal cancer in women over age 18 years living in Loire. The second survey was regarding onco-geriatric screening through two questionnaires : one for the elderly and the other for general practitioner (GP) of the department, evaluating screening for breast, colorectal, prostate, cervical and lung cancer. One hundred sixty six women were included in the first investigation mean age of 47.6 years. Ninety three point six per cent were screening for breast cancer, 19% received Human Papilloma virus vaccine, 83.1% were screening by Papanicolau smear for cervical cancer and finally, 51.7% were screening for colorectal cancer, among the one entering screening program criteria. In the second survey, 44 patients and 28 GP were included. Thirty-eight point six per cent of patients over 74 years continue screening. Only 11.4% were reluctant to screening and in 80% because of anxiety du to the results. Among GP, 50 % continued screening on two major criteria : life expectancy and performans status. The present study shows heterogeneity of screening in this department both rural and working class and gives us a societo-medical photography.

Screening mammography & breast cancer mortality: meta-analysis of quasi-experimental studies

Background

The magnitude of the benefit associated with screening has been debated. We present a meta-analysis of quasi-experimental studies on the effects of mammography screening.

Methods

We searched MEDLINE/PubMed and Embase for articles published through January 31, 2013. Studies were included if they reported: 1) a population-wide breast cancer screening program using mammography with 5+ years of data post-implementation; 2) a comparison group with equal access to therapies; and 3) breast cancer mortality. Studies excluded were: RCTs, case-control, or simulation studies. We defined quasi-experimental as studies that compared either geographical, historical or birth cohorts with a screening program to an equivalent cohort without a screening program. Meta-analyses were conducted in Stata using the metan command, random effects. Meta-analyses were conducted separately for ages screened: under 50, 50 to 69 and over 70 and weighted by population and person-years.

Results

Among 4,903 published papers that were retrieved, 19 studies matched eligibility criteria. Birth cohort studies reported a significant benefit for women screened <age 50, but not for women screened ages 50–69. Significant reductions in breast cancer mortality were observed in historical comparisons. For geographical comparisons, there was a significant 20% reduction in mortality for women <age 50 and a significant 21–22% reduction for women ages 50–69. Studies that tested the interaction of geographical and historical comparisons produced a pooled, significant 13–17% reduction in incident breast cancer mortality for women ages 50–69, but the effects in most individual studies were non-significant. All studies of women ages 70+ were non-significant.

Conclusions

Mammography screening may have modest effects on cancer mortality between the ages of 50 and 69 and non-significant effects for women older than age 70. Results are consistent with meta-analyses of RCTs. Effects on total mortality could not be assessed because of the limited number of studies.

Breast carcinoma detection modes and death in a female population in relation to population-based mammography screening

Purpose

Associations between population-based screening, breast carcinoma detection modes and breast carcinoma death have not been studied using nationwide data at individual level. We evaluated these in Finland, where invitational age is gradually expanding from 50–59 to 50–69 years in 2008–2017. We also predicted breast carcinoma patterns in 2020 to assess the impact of changing invitational policy on breast carcinoma incidence and mortality.

Methods

The data included breast carcinomas in 2000–2010 (n = 48 040), and deaths due to these carcinomas (n = 4722). We divided carcinomas into those detected before or after the screening age, and those detected at the screening age. The latter was further divided into screen-detected and interval carcinomas, and carcinomas in the non-attendees. The prediction of future patterns was based on incidence data from the ten-year period 1998–2007 preceding the period of expanding invitational age in the national programme.

Results

Approximately 13% of in situ carcinomas were detected before, 29% after, and 57% at the screening age. In invasive cancers, the percentages were 16%, 42%, and 42%, respectively. At the screening age, more than half of invasive cancers were screening-detected, one quarter interval cancers, and one out of six cancers in the non-attendees. Almost 60% of breast cancer deaths were due to cancers detected after the screening age. By 2020, breast cancers detected at the screening age will increase from 42% to 65%, and breast cancers detected by screening from 23% to 38%.

Conclusions

The study demonstrates a novel approach to examine associations between breast carcinoma incidence and mortality within and outside population-based screening. The results show mammography screening having a distinct role in overall breast carcinoma incidence and mortality.

Electronic supplementary material

The online version of this article (doi:10.1186/2193-1801-3-348) contains supplementary material, which is available to authorized users.

Variation in detection of ductal carcinoma in situ during screening mammography: a survey within the International Cancer Screening Network

BACKGROUND

There is concern about detection of ductal carcinoma in situ (DCIS) in screening mammography. DCIS accounts for a substantial proportion of screen-detected lesions but its effect on breast cancer mortality is debated. The International Cancer Screening Network conducted a comparative analysis to determine variation in DCIS detection.

PATIENTS AND METHODS

Data were collected during 2004-2008 on number of screening examinations, detected breast cancers, DCIS cases and Globocan 2008 breast cancer incidence rates derived from national or regional cancer registers. We calculated screen-detection rates for breast cancers and DCIS.

RESULTS

Data were obtained from 15 screening settings in 12 countries; 7,176,050 screening examinations; 29,605 breast cancers and 5324 DCIS cases. The ratio between highest and lowest breast cancer incidence was 2.88 (95% confidence interval (CI) 2.76-3.00); 2.97 (95% CI 2.51-3.51) for detection of breast cancer; and 3.49 (95% CI 2.70-4.51) for detection of DCIS.

CONCLUSIONS

Considerable international variation was found in DCIS detection. This variation could not be fully explained by variation in incidence nor in breast cancer detection rates. It suggests the potential for wide discrepancies in management of DCIS resulting in overtreatment of indolent DCIS or undertreatment of potentially curable disease. Comprehensive cancer registration is needed to monitor DCIS detection. Efforts to understand discrepancies and standardise management may improve care.

Breast cancer mortality in mammographic screening in Europe: a review of incidence-based mortality studies

OBJECTIVES

To estimate the impact of service mammography screening on breast cancer mortality using European incidence-based mortality (IBM) studies (or refined mortality studies). IBM studies include only breast cancer deaths occurring in women with breast cancer diagnosed after their first invitation to screening.

METHODS

We conducted a literature review and identified 20 publications based on IBM studies. They were classified according to the method used for estimating the expected breast cancer mortality in the absence of screening: (1) women not yet invited; (2) historical data from the same region as well as from historical and current data from a region without screening; and (3) historical comparison group combined with data for non-participants.

RESULTS

The estimated effect of mammography screening on breast cancer mortality varied across studies. The relative risks were 0.76-0.81 in group 1; 0.75-0.90 in group 2; and 0.52-0.89 in group 3. Study databases overlapped in both Swedish and Finnish studies, adjustment for lead time was not optimal in all studies, and some studies had other methodological limitations. There was less variability in the relative risks after allowing for the methodological shortcomings.

CONCLUSIONS

Based on evidence from the most methodologically sound IBM studies, the most likely impact of European service mammography screening programmes was a breast cancer mortality reduction of 26% (95% confidence interval 13-36%) among women invited for screening and followed up for 6-11 years.

The impact of mammographic screening on breast cancer mortality in Europe: a review of observational studies

OBJECTIVES

To assess the impact of population-based mammographic screening on breast cancer mortality in Europe, considering different methodologies and limitations of the data.

METHODS

We conducted a systematic literature review of European trend studies (n = 17), incidence-based mortality (IBM) studies (n = 20) and case-control (CC) studies (n = 8). Estimates of the reduction in breast cancer mortality for women invited versus not invited and/or for women screened versus not screened were obtained. The results of IBM studies and CC studies were each pooled using a random effects meta-analysis.

RESULTS

Twelve of the 17 trend studies quantified the impact of population-based screening on breast cancer mortality. The estimated breast cancer mortality reductions ranged from 1% to 9% per year in studies reporting an annual percentage change, and from 28% to 36% in those comparing post- and prescreening periods. In the IBM studies, the pooled mortality reduction was 25% (relative risk [RR] 0.75, 95% confidence interval [CI] 0.69-0.81) among invited women and 38% (RR 0.62, 95% CI 0.56-0.69) among those actually screened. The corresponding pooled estimates from the CC studies were 31% (odds ratio [OR] 0.69, 95% CI 0.57-0.83), and 48% (OR 0.52, 95% CI 0.42-0.65) adjusted for self-selection.

CONCLUSIONS

Valid observational designs are those where sufficient longitudinal individual data are available, directly linking a woman's screening history to her cause of death. From such studies, the best 'European' estimate of breast cancer mortality reduction is 25-31% for women invited for screening, and 38-48% for women actually screened. Much of the current controversy on breast cancer screening is due to the use of inappropriate methodological approaches that are unable to capture the true effect of mammographic screening.

Mammography activity in Norway 1983 to 2008

BACKGROUND

In Norway, an organized screening mammography program, the Norwegian Breast Cancer Screening Program (NBCSP) started in four counties in 1996 and became nationwide in 2004. We collected data on pre-program screening activity, and in view of this activity we evaluated the potential impact of the program on breast cancer mortality in Norway.

METHODS

We searched data sources on mammography activity in Norway. Three data sources reported on examination activity, and two on self-reported examinations. We aimed at calculating annual number of women examined by mammography from 1983 to 2008, and coverage rate in program and non-program Norwegian counties.

RESULTS

The annual number of women examined increased from 5000 in 1983 to 110,000 in 1993 to reach its maximum of 131,000 in 2002, excluding program examinations. The annual number of women examined in the organized program increased from 1996 to a steady state about 190,000 in 2004. Prior to start of the organized program, 40% of women in target age groups reported to have had mammography examination. During the years 1996-2002, 64% of first participants in the organized program reported to have been examined previously. Assuming that the Norwegian program would in absence of prior screening have decreased breast cancer mortality by 25%, and that the activity in- and outside the organized program were equally effective, the measured effect of the organized program would under actual circumstances be a reduction of 11%.

CONCLUSION

The example of Norway illustrates that although monitoring of screening outcome is highly warranted, this may be seriously jeopardized if use of mammography examinations was widespread prior to implementation of an organized program.

Effects of annual vs triennial mammography interval on breast cancer incidence and mortality in ages 40-49 in Finland

Background:

The aim of this study was to evaluate the effects of mammography screening invitation interval on breast cancer mortality in women aged 40–49 years.

Methods:

Since 1987 in Turku, Finland, women aged 40–49 years and born in even calendar years were invited for mammography screening annually and those born in odd years triennially. The female cohorts born during 1945–1955 were followed for up to 10 years for incident breast cancers and thereafter for an additional 3 years for mortality.

Results:

Among 14 765 women free of breast cancer at age 40, there were 207 incident primary invasive breast cancers diagnosed before the age of 50. Of these, 36 women died of breast cancer. The mean follow-up time for cancer incidence was 9.8 years and for mortality 12.8 years. The incidence of breast cancer was similar in the annual and triennial invitation groups (RR: 0.98, 95% confidence interval (CI): 0.75–1.29). Further, there were no significant differences in overall mortality (RR: 1.20, 95% CI: 0.99–1.46) or in incidence-based breast cancer mortality (RR: 1.14, 95% CI: 0.59–1.27) between the annual and triennial invitation groups.

Conclusions:

There were no differences in the incidence of breast cancer or incidence-based breast cancer mortality between the women who were invited for screening annually or triennially.

Breast cancer screening for women ages 50 to 69 years a systematic review of observational evidence

OBJECTIVE

To systematically review the observational evidence concerning the effect of screening on breast cancer mortality in actual populations of women ages 50-69 years.

METHODS

We searched MEDLINE and multiple reference lists for relevant cohort and ecologic studies. At least 2 authors reviewed abstracts and full texts of studies meeting eligibility criteria. We rated each accepted study on standard quality criteria and developed a Summary Evidence Table.

RESULTS

Seventeen studies met eligibility criteria. Five studies found no to small effect of screening (0-12% relative risk reduction [RRR] in breast cancer mortality), 4 found a large effect (greater than 33% RRR), and 8 found a moderate effect (13% to 33% reduction). The authors found concerns about quality in all studies. There was insufficient evidence to determine whether the effectiveness of screening is decreasing over time.

CONCLUSIONS

Current observational evidence shows that breast cancer screening in actual populations of women ages 50 to 69 reduces breast cancer mortality; the magnitude of the effect is probably smaller than predicted in the randomized controlled trials. Because the magnitude may change (either increase or decrease) in the future, further ecologic studies are needed. The methodology and infrastructure for these studies should be improved.

Population studies of the effectiveness of mammographic screening

OBJECTIVE

To examine population data to see whether survival from breast cancer has improved differentially in screened and unscreened women and examine published studies on mammographic screening to determine whether there is evidence that screening is no longer effective.

METHODS

Data was reviewed on trends in breast cancer specific survival among women participating and not participating in the British Columbia Breast Screening Program. Population studies of mammographic screening published between 2000 and 2010 with breast cancer mortality as the outcome were also reviewed.

RESULTS

Breast cancer specific survival in British Columbia improved more in screening participants than non-participants, HR=0.74 (0.58,0.93) between the periods 1990-4 and 2000-4. Among the published studies of mortality between 2000 and 2010 selected from different jurisdictions all had found a reduction in breast cancer mortality although this was not always statistically different from zero. Studies had used a range of designs and evaluative methods which may have contributed to the magnitude of the effect reported.

CONCLUSION

No evidence was found in the British Columbia data and the published studies reviewed, that treatment or other changes, had caused mammographic screening to become ineffective.

Advantages and Disadvantages of Mammography Screening

Mammography screening is the only method presently considered appropriate for mass screening of asymptomatic women. Its frequent use, however, warrants diligent analysis of potential side effects. Radiation risk is far below the natural yearly risk of breast cancer and should not be used as an argument against screening. False-positive calls lead to additional imaging or histopathological assessment, mainly percutaneous breast biopsy. These measures are tolerated and accepted fairly well. Their number is limited by strict quality assurance and constant training. Interval cancers represent a limitation of breast screening that should prompt further research for optimization. Evaluation of overdiagnosis is a highly debated topic in the literature. According to the probably most realistic available calculations, overdiagnosis is acceptable as it is compensated by the potential mortality reduction. Nonetheless, this potential side effect warrants optimal adjustment of therapy to the patient's individual risk. The mortality reduction seen in randomized studies was confirmed by results from national screening programs. A recent case referent study indicated that improvements in mortality reduction run parallel to improved mammographic techniques. Use of less aggressive therapies is another valuable effect of screening. Awareness of potential problems, strict quality assurance, and further research should help to further develop screening programs.

Socioeconomic status as determinant for participation in mammography screening: assessing the difference between using women's own versus their partner's

OBJECTIVES

Earlier research has shown that participation in mammography screening tends to vary across socioeconomic levels. We assessed the difference between using the woman's own socioeconomic status (SES) and using that of her household or partner as determinant of participation in mammography screening.

METHODS

Participation data from two mammography screening programs in Denmark were linked to a national SES classification system providing data for each citizen, their partner, and household. We calculated the odds ratio of non-participation across SES levels using the woman's own, the household's, and her partner's SES status, respectively.

RESULTS

When using the woman's own SES, the odds ratio of non-participation showed a clear U-shape across SES levels, in both programs. When using the partner's SES the difference in non-participation across SES levels was significantly smaller (p < 0.001).

CONCLUSIONS

To what extent SES was a determinant for screening participation strongly depended on whether using the woman's own SES or that of her partner. In a public health perspective it is important to take this into account when addressing the problem of non-attendance in screening.

[Prevalence of non-utilization of mammography and associated factors in elderly women]

This study analyzes the prevalence of non-utilization of mammography among older women, according to socio-demographic variables, health status, and use of preventive health services. This was a cross-sectional study including women 60 years or older. We interviewed 4,621 women 60 to 106 years of age; the majority were widows (51.8%) and had little or no schooling (53.8%). Most (89%) reported health problems, and 66.4% used private medical care. Prevalence of self-reported mammography was 72.1%. Gynecological visits (PR = 2.39; 95%CI: 2.04-2.80), Pap smear (PR = 3.24; 95%CI: 2.89-3.63), years of schooling (PR = 1.07; 95%CI: 1.02-1.12), health care insurance (PR = 1.16; 95%CI: 1.11-1.20), physician visits (PR = 1.23; 95%CI: 1.11-1.37), age (PR = 1.12; 95%CI: 1.08-1.17), marital status (PR = 1.05; 95%CI: 1.00-1.09), and barriers to health services (PR = 0.94; 95%CI: 0.89-0.98) were also associated with non-utilization of mammography. These associations may be partially explained by lack of knowledge, poor access to public health services, and cultural factors related to the aging process and reproductive incapacity.

Evaluation of breast cancer service screening programme with a Bayesian approach: mortality analysis in a Finnish region

Evaluation of long-term effectiveness of population-based breast cancer service screening program in a small geographic area may suffer from self-selection bias and small samples. Under a prospective cohort design with exposed and non-exposed groups classified by whether women attended the screen upon invitation, we proposed a Bayesian acyclic graphic model for correcting self-selection bias with or without incorporation of prior information derived from previous studies with an identical screening program in Sweden by chronological order and applied it to an organized breast cancer service screening program in Pirkanmaa center of Finland. The relative mortality rate of breast cancer was 0.27 (95% CI 0.12-0.61) for the exposed group versus the non-exposed group without adjusting for self-selection bias. With adjustment for selection-bias, the adjusted relative mortality rate without using previous data was 0.76 (95% CI 0.49-1.15), whereas a statistically significant result was achieved [0.73 (95% CI 0.57-0.93)] with incorporation of previous information. With the incorporation of external data sources from Sweden in chronological order, adjusted relative mortality rate was 0.67 (0.55-0.80). We demonstrated how to apply a Bayesian acyclic graphic model with self-selection bias adjustment to evaluating an organized but non-randomized breast cancer screening program in a small geographic area with a significant 27% mortality reduction that is consistent with the previous result but more precise. Around 33% mortality was estimated by taking previous randomized controlled data from Sweden.

Cancer screenings, diagnostic technology evolution, and cancer control

Screening should allow for the anticipation of cancer diagnosis at an earlier stage, when curative treatment is possible. Screening for cervical, large bowel, and breast cancer were shown to be effective in reducing mortality. The wide acceptance of the screening concept led to the wide diffusion also of screening of uncertain benefit against prostate cancer and skin melanoma. Diagnostic technologies are continuously evolving, and new tests are proposed to improve existing screenings or as screening tests for additional cancer sites (e.g., lung cancer). Cancer screening, however, is a complex and costly intervention that does not result only in benefits but also may cause harm. A major emerging problem of screening is overdiagnosis, or the detection of cases that would have not progressed to the symptomatic phase in the absence of screening. Thus, both experimental and observational evaluation studies are needed to reduce harm caused by screenings and to select effective interventions among many proposed innovations. Finally, the research of markers to assess the aggressive nature of screen-detected lesions is of great importance to improve screenings ' harm/benefit ratio.

Comparison of cancer registry and clinical data as predictors for breast cancer survival

BACKGROUND

In spite of the increasing amount of clinically relevant information for survival from breast cancer, the amount of data recorded in a population-based cancer registry is limited and the registry-based survival predictions are routinely made without clinical details.

OBJECTIVE

To find out how important is the role of screening and clinical tumor characteristics in addition to cancer registry information in describing the breast cancer survival.

METHODS

A representative clinical database on 483 breast cancer patients diagnosed during 1996-1997 in Tampere University Hospital Area was linked with Finnish Cancer Registry data and a survival model including the available registry variables was compared to models including screen-detection information and clinical tumor characteristics also.

RESULTS AND CONCLUSION

Estimates of registry stage and age act as surrogates for clinical variables and mammography-detection. The surrogacy was found to be almost complete indicating that clinical variables are not necessarily needed when making breast cancer mortality predictions based on a population-based cancer registry. In cases with dissimilar staging cancer registry stage gave a better picture of the breast cancer survival than the clinical stage.

Does educational level determine screening participation?

The objective of this study was to test the hypothesis that nonparticipation in organized mammography screening is due to insufficient understanding of the information in the invitation letter by relating educational level to user pattern. Data from two Danish mammography screening programmes in Copenhagen, 1991-1999, and Funen, 1993-2001 were taken for this study. The Danish Central Population Register was used to define target groups; screened participation data were provided by the health authority, and data on highest obtained education came from Statistics Denmark. Data on all breast imaging in 2000 outside organized screening were provided by radiology clinics. Included were all women eligible for at least three screens, and participation was classified into four mutually exclusive user groups. Organized mammography screening programmes in Copenhagen and Funen, Denmark were used as field of this study. Main outcome measures were age-adjusted relative risks (RR) and 95% confidence intervals (CI) of 'never use' versus 'always use' of screening by educational level, using women with secretarial/sales education as baseline. The RR of 'never use' was 1.65 (95% CI: 1.37-1.99) in Copenhagen and 1.93 (95% CI: 1.42-2.62) in Funen for academics, 1.60 (95% CI: 1.48-1.73) in Copenhagen and 1.26 (95% CI: 1.14-1.39) Funen for women with lower primary educational level. Taking other breast imaging into account, the RR was 1.60 (95% CI: 1.32-1.95) for academics in Copenhagen, and 1.90 (95% CI: 1.75-2.07) for women with lower primary education. In conclusion, our results did not support the hypothesis that lack of understanding the information in the invitation letter explains nonparticipation. 'Never use' was not inversely associated with the level of education, but showed a U-shaped association, even when use of breast imaging outside organized screening was taken into account.

Estimating the cumulative risk of a false-positive under a regimen involving various types of cancer screening tests

OBJECTIVES

When evaluating screening for the early detection of cancer, it is important to estimate both harms and benefits. One common harm is a false-positive (FP), which is a positive screening result, perhaps followed by an invasive test, with no cancer detected on the diagnostic work-up or within a specified time period. An important goal is to estimate the risk of at least one FP, which we call the cumulative risk of an FP, if persons took a regimen of various screening tests, as is commonly recommended. The estimation is complicated because the data come from a study in which subjects are offered various screening tests in rounds with some missing tests in most subjects. Previous methods for estimating cumulative risk of FPs with a single type of test are not directly applicable, so a new approach was developed.

METHODS

The tests were ordered by appearance, where the last test was either the first FP (analogous to a failure time) or the last test taken with no FPs having occurred on that test or previously (analogous to a censoring time). We applied a Kaplan-Meier approach for survival analysis with the innovation that the hazard for a first FP for a given test depends on the type of test and number of previous tests of that type which were taken.

RESULTS

The method is illustrated with data from the screening arm of the randomized Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial. With an FP defined as a diagnostic work-up in the absence of cancer (or advanced adenoma) within three years, the probability of at least one FP among 14 tests in men was 60.5% with 95% confidence interval of (59.3%, 61.6%).

CONCLUSION

A simple estimate is proposed for the probability of at least one FP if persons took a regimen of multiple screening tests of different types. The methodology is useful for summarizing the burden of multiphasic screening programmes.

The effect of an organized, nationwide breast cancer screening programme on non-organized mammography activities

OBJECTIVES

To analyse the effect of an organized, nationwide breast cancer screening programme on non-organized mammography activities in Hungary.

SETTING

The nationwide dataset of the Hungarian National Health Insurance Fund Administration covering the years 2000-2005.

METHODS

Data derived from the nationwide database of the Hungarian National Health Insurance Fund Administration. The study includes all women undergoing mammography before (2000-2001) and after (2002-2003/2004-2005) the introduction of organized screening.

RESULTS

The number of women having non-organized (opportunistic/diagnostic) mammograms was around 250,000 in 2000-2001, but increased to 350,000 in 2005. In the age group 45-64 years in 2000-2001, only 27.4% of all women undergoing mammography were examined within locally-organized programmes. After the introduction of the nationwide programme, this percentage increased to 61.0% in 2002-2003, and 56.3% in 2004-2005. After the introduction of the nationwide organized programme (2002-2003), the proportion of organized screening mammographies remained among the highest in county Hajdú-Bihar (78.4%) and Zala (88.3%) and increased significantly in county Vas (87.7%).

CONCLUSION

The introduction of an organized nationwide screening programme in Hungary resulted in increases in the number of screening mammographies, and also of non-organized mammographies. Although the ratio of organized screening versus non-organized mammography changed in favour of screening mammographies, there are large within-country differences between counties.

Breast cancer mortality with varying invitational policies in organised mammography

We examined the effect of different invitational policies on the reduction of breast cancer mortality at 60–79 years of age within the Finnish mammography programme in 1992–2003, which varied in its coverage at 60–69 years of age. The data from 260 municipalities were grouped into three categories: regular invitations at 50–59 years of age only, regular invitations at 50–69 years of age, and regular invitations at 50–59 years of age with irregular invitations at 60–69 years of age. Observed deaths from breast cancer were compared to those expected without screening among all women and among the screened and non-screened women. Observed deaths were obtained from population data and from a cohort follow-up in 1992–2003. Expected deaths were derived by modelling breast cancer mortality at population level in 1974–1985 and 1992–2003. The reduction in breast cancer mortality was strongest, 28% (0.72, 0.51–0.97), in municipalities with regular invitations at 50–69 years of age. No overall effect at 60–79 years of age was observed with regular invitations at 50–59 years of age. The study confirms a reduction by screening of breast cancer mortality in Finland. Uniform extension of invitations to 60–69 years of age would increase the number of prevented breast cancer deaths among the elderly.

Impacts of the Finnish service screening programme on breast cancer rates

BACKGROUND

The aim of the current study was to examine impacts of the Finnish breast cancer (BC) screening programme on the population-based incidence and mortality rates. The programme has been historically targeted to a rather narrow age band, mainly women of ages 50-59 years.

METHODS

The study was based on the information on breast cancer during 1971-2003 from the files of the Finnish Cancer Registry. Incidence, cause-specific mortality as well as incidence-based (refined) mortality from BC were analysed with Poisson regression. Age-specific incidence and routine cause-specific mortality were estimated for the most recent five-year period available; incidence-based mortality, respectively, for the whole steady state of the programme, 1992-2003.

RESULTS

There was excess BC incidence with actual screening ages; incidence in ages 50-69 was increased 8% (95 CI 2.9-13.4). There was an increasing temporal tendency in the incidence of localised BC; and, respectively, a decrease in that of non-localised BC. The latter was most consistent in age groups where screening had been on-going several years or eventually after the last screen. The refined mortality rate from BC diagnosed in ages 50-69 was decreased with -11.1% (95% CI -19.4, -2.1).

CONCLUSIONS

The current study demonstrates that BC screening in Finland is effective in reducing mortality rates from breast cancers, even though the impact on the population level is smaller than expected based on the results from randomised trials among women screened in age 50 to 69. This may be explained by the rather young age group targeted in our country. Consideration whether to targeted screening up to age 69 is warranted.

Organised mammography screening reduces breast cancer mortality: a cohort study from Finland

We evaluated the effectiveness and the efficacy of population-based mammography programme in Finland, and explored associations between the screening performance and the screening efficacy. The main outcome, incidence-based mortality from breast cancer, was estimated by invitation, participation, age at death, and screening centres categorised by recall rates. The study was based on an individual followup of screening invitees and participants from 1992 to 2003. The coverage of screening invitations was 95% among 50-59 years old women, and 20-40% among women aged 60-69 years. We compared observed deaths from breast cancer to expected breast cancer deaths without screening in ages 50-69 at death. The observed deaths were obtained from a cohort of individual invitees (n = 361,848). The expected deaths were defined by modelling breast cancer mortality from 1974 to 1985 and 1992 to 2003 at population level. The population data were derived from the same municipalities (n = 260) that were incorporated into the cohort. The breast cancer mortality among the invited women was reduced by 22% (relative risk 0.78, 95% confidence interval 0.70-0.87). After adjusting for the self-selection, the efficacy among the participants was 28% (0.72,0.56-0.88). No clear association between the recall rates and the screening efficacy was observed. The organised mammography screening in Finland is effective. The relationship between the estimates of process and outcome of mammography is not yet straightforward: effectiveness and efficacy remain the best estimates for evaluating the success of mammography screening.

Auditing and benchmarks in screening and diagnostic mammography

Radiologists can use outcome data such as cancer size and stage to determine how well their own practice provides benefit to their patients and can use measures such as screening recall rates and positive predictive values to assess how well adverse consequences are being contained. New data on national benchmarks for screening and diagnostic mammography in the United States allow radiologists to evaluate their own performance with respect to their peers. This article discusses recommended outcome values in the United States and Europe, current Mammography Quality Standards Act audit requirements, and Institute of Medicine proposals for future requirements.

Socio-demographic determinants of participation in mammography screening

Our objective was to use individual data on socio-demographic characteristics to identify predictors of participation in mammography screening and control to what extent they can explain the regional difference. We used data from mammography screening programmes in Copenhagen, 1991-1999, and Funen, 1993-2001, Denmark. Target groups were identified from the Population Register, screening data came from the health authority, and socio-demographic data from Statistics Denmark. Included were women eligible for at least 3 screens. The crude RR of never use versus always use was 3.21 (95%CI, 3.07-3.35) for Copenhagen versus Funen, and the adjusted RR was 2.55 (95%CI, 2.43-2.67). The adjusted RR for never use among women without contact to a primary care physician was 2.50 (95% CI, 2.31-2.71) and 2.89 (95% CI, 2.66-3.14), and for women without dental care 2.94 (95% CI, 2.77-3.12) and 2.88 (95% CI, 2.68-3.10) for Copenhagen and Funen, respectively. Other important predictive factors for nonparticipation were not being married and not being Danish. In conclusion, to enhance participation in mammography screening programmes special attention needs to be given to women not using other primary health care services. All women in Copenhagen, irrespective of their socio-demographic characteristics, had low participation. Screening programmes have to find ways to handle this urbanity factor.

Estimating the benefits of mammography screening: the impact of study design

BACKGROUND

Mammography screening is justifiable only if it leads to reduction in breast cancer mortality. However, evaluation of routine screening is not straightforward, as no unscreened control group is available. We report here on a cohort study of the effect of routine mammography on breast cancer mortality, and illustrate how variations in the analytic approach can affect the conclusions.

METHODS

We used data from the mammography screening program in Copenhagen, Denmark, for the period 1991-2001. We used local historical, concurrent regional, and historical regional control groups, and included only deaths from breast cancers diagnosed during the observation periods. We examined the impact of various control groups, of including all breast cancer deaths, and of using individual data versus routine statistics.

RESULTS

Combining all 3 control groups gave an estimated 25% reduction in breast cancer mortality. The estimate was 20% using only a local historical control group, and 9% using only a concurrent regional control group. Including all breast cancer deaths resulted in an estimate of 21% reduction in breast cancer mortality. Using routine statistics and a concurrent regional control group resulted in an estimated increase of 6% in breast cancer mortality.

CONCLUSION

Estimated changes in breast cancer mortality following the introduction of routine mammography ranged from a 25% reduction (based on the best methodology) to a 6% increase with a less rigid study design. The estimated effect of routine mammography on breast cancer mortality is thus highly dependent on study design.