Interpreting Breast Cancer Mortality Trends Related to Introduction of Mammography Screening: A Simulation Study
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PROVIDER: S-EPMC9549205 | biostudies-literature | 2022 Jan
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Project description:BackgroundDespite the relatively low breast cancer incidence in Estonia, mortality remains high, and participation in mammography screening is below the recommended 70%. The objective of this register-based study was to evaluate incidence-based (IB) breast cancer mortality before and after the introduction of organized mammography screening in 2004.MethodsBreast cancer deaths individually linked to breast cancer diagnosis were obtained from the Estonian Cancer Registry and used for calculating IB mortality. We compared age-specific IB mortality rates across 5-year birth cohorts and 5-year periods. Poisson regression was used to compare IB mortality for one age group invited to screening (50-63) and three age groups not invited to screening (30-49, 65-69, and 70+) during two periods before and after screening initiation (1993-2003 and 2004-2014). Joinpoint regression was used for age-standardized incidence and IB mortality trends.ResultsAge-standardized IB mortality has been decreasing since 1997. Age-specific IB mortality for birth cohorts never exposed to screening showed a continuous increase with age, while in cohorts exposed to organized screening the mortality curve flattened or declined after the age of first invitation. Significant decreases in mortality from 1993-2003 to 2004-2014 were seen in the 30-49 (age-adjusted rate ratio 0.51, 95% CI 90.42-0.63) and 50-63 (0.65, 95% CI 0.56-0.74) age groups, while no decline was seen in the 65-69 and 70+ age groups.ConclusionsThe age specific IB mortality curves in birth cohorts exposed to screening and the significant mortality decline in the target age group after the initiation of the organized program suggest a beneficial effect of screening. Improved treatment without screening has not reduced mortality in older age groups. Our results support raising the upper screening age limit to 74 years.
| S-EPMC11297520 | biostudies-literature
Project description:ObjectiveTo evaluate the effectiveness of contemporary mammography screening using individual information about screening history and breast cancer mortality from public screening programmes.DesignProspective cohort study of Norwegian women who were followed between 1986 and 2009. Within that period (1995-2005), a national mammography screening programme was gradually implemented, with biennial invitations sent to women aged 50-69 years.ParticipantsAll Norwegian women aged 50-79 between 1986 and 2009.Main outcome measuresMultiple Poisson regression analysis was used to estimate breast cancer mortality rate ratios comparing women who were invited to screening (intention to screen) with women who were not invited, with a clear distinction between cases of breast cancer diagnosed before (without potential for screening effect) and after (with potential for screening effect) the first invitation for screening. We took competing causes of death into account by censoring women from further follow-up who died from other causes. Based on the observed mortality reduction combined with the all cause and breast cancer specific mortality in Norway in 2009, we used the CISNET (Cancer Intervention and Surveillance Modeling Network) Stanford simulation model to estimate how many women would need to be invited to biennial mammography screening in the age group 50-69 years to prevent one breast cancer death during their lifetime.ResultsDuring 15 193 034 person years of observation (1986-2009), deaths from breast cancer occurred in 1175 women with a diagnosis after being invited to screening and 8996 women who had not been invited before diagnosis. After adjustment for age, birth cohort, county of residence, and national trends in deaths from breast cancer, the mortality rate ratio associated with being invited to mammography screening was 0.72 (95% confidence interval 0.64 to 0.79). To prevent one death from breast cancer, 368 (95% confidence interval 266 to 508) women would need to be invited to screening.ConclusionInvitation to modern mammography screening may reduce deaths from breast cancer by about 28%.
| S-EPMC4061379 | biostudies-literature
Project description:Survival in female breast cancers has generally improved but the relative contribution of early detection or treatment in this positive development is not known. Our aim was to assess the possible role of national mammography screening programs in survival improvement. Such screening has been offered to women, usually at 50-69 years of age, in Finland and Sweden since the 1980s and in Denmark and Norway since the 1990s. Participation rates have been high, ranging from 60% to 90%. We analyzed incidence and mortality changes and relative 5- and 10-year survival trends in breast cancer as novel measures in these countries using the NORDCAN database. Survival trends were compared in age groups of women who were screened to those who were not screened. We observed a relative survival advantage in 5-year and 10-year survival in the screened age groups after the period of national mammography screening was in place and this was consistent in each country. Timing and age-specific targeting of the improvements suggest that mammography may have contributed to the survival benefits. However, as we had no individual data on women who used the service, more detailed studies are needed to confirm the suggested survival advantage, particularly concerning mortality in stage-specific breast cancer.
| S-EPMC9736677 | biostudies-literature
Project description:BackgroundThe 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.MethodsWe 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.ResultsAmong 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.ConclusionsMammography 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.
| S-EPMC4041743 | biostudies-literature
Project description:ObjectiveTo determine whether the previously observed 25% reduction in breast cancer mortality in Copenhagen following the introduction of mammography screening was indeed due to screening, by using an additional screening region and five years additional follow-up.DesignWe used Poisson regression analyses adjusted for changes in age distribution to compare the annual percentage change in breast cancer mortality in areas where screening was used with the change in areas where it was not used during 10 years before screening was introduced and for 10 years after screening was in practice (starting five years after introduction of screening).SettingCopenhagen, where mammography screening started in 1991, and Funen county, where screening was introduced in 1993. The rest of Denmark (about 80% of the population) served as an unscreened control group.ParticipantsAll Danish women recorded in the Cause of Death Register and Statistics Denmark for 1971-2006.Main outcome measureAnnual percentage change in breast cancer mortality in regions offering mammography screening and those not offering screening.ResultsIn women who could benefit from screening (ages 55-74 years), we found a mortality decline of 1% per year in the screening areas (relative risk (RR) 0.99, 95% confidence interval (CI) 0.96 to 1.01) during the 10 year period when screening could have had an effect (1997-2006). In women of the same age in the non-screening areas, there was a decline of 2% in mortality per year (RR 0.98, 95% CI 0.97 to 0.99) in the same 10 year period. In women who were too young to benefit from screening (ages 35-55 years), breast cancer mortality during 1997-2006 declined 5% per year (RR 0.95, CI 0.92 to 0.98) in the screened areas and 6% per year (RR 0.94, CI 0.92 to 0.95) in the non-screened areas. For the older age groups (75-84 years), there was little change in breast cancer mortality over time in both screened and non-screened areas. Trends were less clear during the 10 year period before screening was introduced, with a possible increase in mortality in women aged less than 75 years in the non-screened regions.ConclusionsWe were unable to find an effect of the Danish screening programme on breast cancer mortality. The reductions in breast cancer mortality we observed in screening regions were similar or less than those in non-screened areas and in age groups too young to benefit from screening, and are more likely explained by changes in risk factors and improved treatment than by screening mammography.
| S-EPMC2844939 | biostudies-literature
Project description: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.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.2 simulation-modeling approaches.U.S. population.Women aged 40 to 74 years.Annual or biennial digital mammography screening from age 40, 45, or 50 years until age 74 years.Lifetime breast cancer deaths averted (benefits) and radiation-induced breast cancer incidence and mortality (harms) per 100,000 women screened.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.Life-years lost from radiation-induced breast cancer could not be estimated.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.Agency for Healthcare Research and Quality, U.S. Preventive Services Task Force, National Cancer Institute.
| S-EPMC4878445 | biostudies-literature
Project description:BackgroundReductions in breast cancer mortality observed over the last three decades are partly due to improved patient management, which may erode the benefit-harm balance of mammography screening.MethodsWe estimated the numbers of women needed to invite (NNI) to prevent one breast cancer death within 10 years. Four scenarios of screening effectiveness (5-20% mortality reduction) were applied on 10,580 breast cancer deaths among Norwegian women aged 50-75 years from 1986 to 2016. We used three scenarios of overdiagnosis (10-40% excess breast cancers during screening period) for estimating ratios of numbers of overdiagnosed breast cancers for each breast cancer death prevented.ResultsUnder the base case scenario of 20% breast cancer mortality reduction and 20% overdiagnosis, the NNI rose from 731 (95% CI: 644-830) women in 1996 to 1364 (95% CI: 1181-1577) women in 2016, while the number of women with overdiagnosed cancer for each breast cancer death prevented rose from 3.2 in 1996 to 5.4 in 2016. For a mortality reduction of 8.7%, the ratio of overdiagnosed breast cancers per breast cancer death prevented rose from 7.4 in 1996 to 14.0 in 2016. For a mortality reduction of 5%, the ratio rose from 12.8 in 1996 to 25.2 in 2016.ConclusionsDue to increasingly potent therapeutic modalities, the benefit in terms of reduced breast cancer mortality declines while the harms, including overdiagnosis, are unaffected. Future improvements in breast cancer patient management will further deteriorate the benefit-harm ratio of screening.
| S-EPMC9341840 | biostudies-literature
Project description:IntroductionIn the past decades, mortality due to breast cancer has declined considerably in Switzerland and other developed countries. The reasons for this decline remain controversial as several factors occurred almost simultaneously, including important advances in treatment approaches, breast cancer awareness and the introduction of mammography screening programmes in many European countries. In Switzerland, mammography screening programmes (MSPs) have existed in some regions for over 20 years but do not yet exist in others. This offers the possibility to analyse its effects with modern spatiotemporal methodology. We aimed to assess the spatiotemporal patterns and the effect of MSPs on breast cancer mortality.SettingSwitzerland.ParticipantsThe study covers breast cancer deaths of the female population of Switzerland during the period 1969-2012. We retrieved data from the Swiss Federal Statistical Office aggregated on a small-area level.DesignWe fitted Bayesian hierarchical spatiotemporal models on death rates indirectly standardised by national references. We used linguistic region, degree of urbanisation, duration of population-based screening programmes and socioeconomic index as covariates.ResultsIn Switzerland, breast cancer mortality in women slightly increased until 1989-1992 and declined strongly thereafter. Until 2009-2012, the standardised mortality ratio declined to 57% (95% CI 54% to 60%) of the 1969-1972 value. None of the other coefficients of the spatial regressions had a significant effect on breast cancer mortality. In 2009-2012, no region had significantly elevated or reduced breast cancer mortality at 95% credible interval level compared with the national mean.ConclusionThere has been a strong reduction of breast cancer mortality from the 1990s onwards. No important spatial disparities were observed. The factors studied (urbanisation, language, duration of population-based MSP and socioeconomic characteristics) did not seem to have an influence on them. Low participation rates and opportunistic screening use may have contributed to the low impact of MSPs.
| S-EPMC5857683 | biostudies-literature
Project description:BackgroundThe usefulness of case-control studies has been questioned. Our aim was to evaluate the long-term effect of screening on breast cancer mortality within the population-based mammography programme in Finland using a case-control design, and to compare the analyses with the earlier cohort study.MethodsThe cases were women invited to screening, diagnosed and died from breast cancer in 1992-2011 while being 50-84 years at death. We chose 10 controls for each case with non-restrictive eligibility criteria. Our data included 1907 cases and 18 978 matched controls. We analysed associations between the screening participation and the risk of breast cancer death using the conditional Cox proportional hazards model. The effect estimates were corrected for self-selection bias.ResultsAn overall effect of screening was 0.67 (95% confidence interval (CI): 0.49-0.90), and that remained unchanged over time. Analyses with matching criteria comparable to the cohort study yielded an effect (0.70, 95% CI: 0.49-1.00) in 1992-2003 similar to that of the previous cohort analysis (0.72, 95% CI: 0.56-0.88).ConclusionsOrganised mammography screening decreases mortality from breast cancer by 33% among the participants. If made comparable, a case-cohort study can yield effect estimates similar to a cohort study.
| S-EPMC4984912 | biostudies-literature
Project description:ObjectivesThis study surveyed the views of breast screening readers in the UK on how to incorporate Artificial Intelligence (AI) technology into breast screening mammography.MethodsAn online questionnaire was circulated to the UK breast screening readers. Questions included their degree of approval of four AI implementation scenarios: AI as triage, AI as a companion reader/reader aid, AI replacing one of the initial two readers, and AI replacing all readers. They were also asked to rank five AI representation options (discrete opinion; mammographic scoring; percentage score with 100% indicating malignancy; region of suspicion; heat map) and indicate which evidence they considered necessary to support the implementation of AI into their practice among six options offered.ResultsThe survey had 87 nationally accredited respondents across the UK; 73 completed the survey in full. Respondents approved of AI replacing one of the initial two human readers and objected to AI replacing all human readers. Participants were divided on AI as triage and AI as a reader companion. A region of suspicion superimposed on the image was the preferred AI representation option. Most screen readers considered national guidelines (77%), studies using a nationally representative dataset (65%) and independent prospective studies (60%) as essential evidence. Participants' free-text comments highlighted concerns and the need for additional validation.ConclusionsOverall, screen readers supported the introduction of AI as a partial replacement of human readers and preferred a graphical indication of the suspected tumour area, with further evidence and national guidelines considered crucial prior to implementation.
| S-EPMC9733732 | biostudies-literature