Trends In Breast Cancer Mortality Research Articles

Mammography Screening for Women Aged 75 Years or More

Evaluation of: Schonberg MA, Breslau ES, McCarthy EP. Targeting of mammography screening according to life expectancy in women aged 75 and older. J. Am. Geriatr. Soc. 61(3), 388–395 (2013). The evidence on the effectiveness of mammography screening for women aged 75 years or more has been reviewed. As there is no randomized screening trial evidence of benefit, the evidence from trials involving younger women have to be extrapolated. However, the relevant trials were performed before recent advances in breast cancer treatment were available, thus the absolute degree of benefit has to be much less than estimated from the trials. Recent trends in breast cancer incidence and mortality in the USA are considered. The majority of deaths from breast cancer in women aged 75 years or more are from cases diagnosed at younger ages. It is probable that less than one in 6000 women aged 75 years or more would benefit from mammography screening.

Trends in Breast Cancer Stage and Mortality in Michigan (1992–2009) by Race, Socioeconomic Status, and Area Healthcare Resources

The long-term effect of socioeconomic status (SES) and healthcare resources availability (HCA) on breast cancer stage of presentation and mortality rates among patients in Michigan is unclear. Using data from the Michigan Department of Community Health (MDCH) between 1992 and 2009, we calculated annual proportions of late-stage diagnosis and age-adjusted breast cancer mortality rates by race and zip code in Michigan. SES and HCA were defined at the zip-code level. Joinpoint regression was used to compare the Average Annual Percent Change (AAPC) in the median zip-code level percent late stage diagnosis and mortality rate for blacks and whites and for each level of SES and HCA. Between 1992 and 2009, the proportion of late stage diagnosis increased among white women [AAPC = 1.0 (0.4, 1.6)], but was statistically unchanged among black women [AAPC = −0.5 (−1.9, 0.8)]. The breast cancer mortality rate declined among whites [AAPC = −1.3% (−1.8,−0.8)], but remained statistically unchanged among blacks [AAPC = −0.3% (−0.3, 1.0)]. In all SES and HCA area types, disparities in percent late stage between blacks and whites appeared to narrow over time, while the differences in breast cancer mortality rates between blacks and whites appeared to increase over time.

Trends in breast cancer incidence and mortality in the United States: implications for prevention

While debate continues regarding short-term changes in breast cancer incidence and the impact of screening on mortality, a long-term view of trends in incidence and mortality may better inform our understanding of the changing patterns of disease and ultimately guide in population-based prevention. Although many factors have influenced breast cancer incidence over the past seven decades, some have played more prominent roles at various times. Changing reproductive patterns, greater longevity, and post-menopausal hormone (estrogen + progesterone) were important in the steady increase before 1980, while mammographic screening, probably in conjunction with escalating combined estrogen + progesterone use, played dominant roles in the post-1980 surge. Accruing evidence also indicates that the rapid drop in 2003 was mostly due to a sharp decline in estrogen + progesterone use. The most paradoxical observation relates to the divergence in incidence and mortality trends most noticeable when mortality rates started to decline shortly after the surge in incidence rates started in 1980. In addition to the dynamic changes in risk factor profiles, the divergence reflects wider uptake of screening mammography, better characterization of tumor biology, and improvements in treatment. The rise in incidence rates over the past three decades is due to an increase in estrogen receptor positive (ER+) tumors, which respond favorably to treatment. On the other hand, the incidence of estrogen receptor negative (ER-) tumors, which respond poorly to hormonal therapy, has been decreasing for almost three decades. Furthermore, widespread adoption of screening mammography has led to tumors being diagnosed at earlier stages when treatment is effective and advances in treatment have ensured adoption of targeted and better tolerated therapies. To achieve long-term success in the primary prevention of breast cancer, a greater understanding of factors responsible for the decrease in ER- tumors is essential. In addition, improving the sensitivity of breast cancer screening to facilitate earlier detection of tumors with very aggressive phenotypes would go a long way in bridging the divergence between incidence and mortality.

Patterns of breast cancer mortality trends in Europe

ObjectivesTo identify patterns of variation in breast cancer mortality in Europe (1980–2010), using a model-based approach. MethodsMortality data were obtained from the World Health Organization database and mixed models were used to describe the time trends in the age-standardized mortality rates (ASMR). Model-based clustering was used to identify clusters of countries with homogeneous variation in ASMR. ResultsThree patterns were identified. Patterns 1 and 2 are characterized by stable or slightly increasing trends in ASMR in the first half of the period analysed, and a clear decline is observed thereafter; in pattern 1 the median of the ASMR is higher, and the highest rates were achieved sooner. Pattern 3 is characterised by a rapid increase in mortality until 1999, declining slowly thereafter. ConclusionThis study provides a general model for the description and interpretation of the variation in breast cancer mortality in Europe, based in three main patterns.

Breast cancer trends in Israeli Jewish and Arab Women, 1996–2007

Breast cancer is the most common malignancy in Israeli Jewish and Arab women. The main objective of this study was to reexamine the trends in breast cancer incidence, mortality, and survival in Israel in 1996 through 2007, as well as the use of mammography. Data were obtained from the Israel National Cancer Registry, the Central Bureau of Statistics, and National Health Surveys. Incidence and mortality rates per 100 000 are age adjusted to the world standard population. Time trends are presented using the joinpoint regression analysis. The relative survival was calculated for the diagnosis years 1996-2003. Data on mammography performance were obtained from the Knowledge, Attitudes and Practices surveys carried out in 2002-2008. From 1996 through 2007, the incidence of in-situ breast cancer increased in both subpopulations whereas the incidence of invasive breast cancer decreased by 3% for Jewish women and increased by 98% for Arab women (P value for 'between-populations' differences <0.001). Reports on having had a mammogram in the last 2 years increased by 16% in Jewish women and by 17% in Arab women in 2002 through 2008 (P=0.880). Breast cancer mortality rates decreased significantly from 24.7 in 1996 to 19.0 in 2007 in Jewish women, but remained stable in Arab women (P=0.041). The 5-year relative survival increased in both subpopulations (P=0.420). The incidence of breast cancer has been stable in Jewish women, but had been increasing rapidly in Arab women throughout 1996-2007. The differences indicate an epidemiologic transition in the Arab minority in Israel. Efforts should focus not only on secondary but also on primary prevention strategies.

Time trends in breast cancer incidence and mortality in a mid-sized northeastern Brazilian city

BackgroundBreast cancer incidence within an area is usually proportional to the area’s income level. High-income areas have shown the highest incidence rates and since 2003, negative trends. As for mortality, rates are often higher in low-income regions. The purpose of this study was to analyze trends in incidence and mortality in a capital city of a northeastern Brazilian state with an intermediate human development index.MethodsIncidence data from the Population-Based Cancer Registry of Aracaju and mortality data from the Official State Database for the period 1996–2006 were used. Incidence and mortality crude and age-standardized rates were calculated. Time trends were obtained using the Joinpoint Regression Model.ResultsFor the period studied, invasive breast cancer age-standardized incidence rates increased annually with an annual percentage change (APC) of 2.9 (95% CI: 1.2-4.6). Significant increasing trends were observed in groups aged 45–54 years (APC: 3.9, 95% CI: 1.4 to 6.6), and 55–64 years (APC: 5.6, 95% CI: 1.8 to 9.6). Age-standardized mortality rates did not show an increasing trend (APC: 3.0, (95% CI: -2.8 to9.1), except for the group aged 55–64 years (APC: 11.3, 95% CI: 1.1 to 22.4).ConclusionsIn the study community, breast cancer showed increasing incidence among women in the peri- and postmenopausal periods. However, mortality did not present increasing overall trends, except for among the group aged 55–64 years. For better outcomes, screening policies should focus on the peri- and postmenopausal periods of women’s lives to diagnose disease.

Trends in Female Breast Cancer Mortality in Urban Centers and Rural Regions of Brazil

BACKGROUND: Social and regional inequalities in Brazil such as delayed diagnosis and a healthcare system with technological limitations hamper the access of socioeconomically deprived women with breast cancer to treatment. Women living in urban centers are known to have a more favorable socioeconomic status and better access to medical and hospital care compared to those living in rural areas. In addition, the coverage of death registration is wider in urban areas. Nevertheless, few studies have been conducted to compare breast cancer mortality in urban centers and rural regions of Brazil. AIMS: To provide a comprehensive picture of mortality trends in female breast cancer in urban centers and rural regions of Brazil. METHODS: This was an ecological study of a temporal series, using mortality database (SIM/WHO) and demographic database (IBGE/WHO). An analysis of the mortality trends between 1980 and 2010 was performed using Poisson regression model. RESULTS: Breast cancer mortality was found to be 3 times lower in rural areas compared to urban areas throughout the entire evaluation period. A declining trend in mortality was found in some urban centers: Porto Alegre (-1.6%; 95%CI: -2.4 to -0.7; p<0.01); Rio de Janeiro (-0.9%; -1.4 to -0.4; p<0.01); Sao Paulo (-1.7%; -2.6 to -0.9; p<0.01); Belo Horizonte (-1.2%; -2.0 to -0.4; p=0.01) and Recife (-0.9%; -1.7 to -0.1; p=0.03). However, increases were found in other urban centers: Fortaleza (0.5%; 95%CI: 0.1–0.9; p=0.02), Belem (0.8%; 0.2–1.5; p=0.01), Joao Pessoa (1.6%; 0.7–2.6; p<0.01), Teresina (4.6%; 1.2–8.2; p=0.01) and Porto Velho (9.0%; 3.8–14.6; p<0.01). A reduction occurred in rural areas of the state of Sao Paulo (-2.8%; 95%CI: -4.4 to -1.3; p<0.01). However, increases were found in most other rural areas in all the different states of the country, the worst being in Maranhao (17.6%; 95%CI: 9.2–26.7; p<0.01), Paraiba (14.5%; 10.0–19.2; p<0.01), Piaui (10.0%; 8.1–13.7; p<0.01) and Alagoas (10.8%; 7.1–14.6; p<0.01). DISCUSSION: In the period between 1980 and 2010, considerable differences were found in mortality from breast cancer in the urban and rural regions of Brazil. These findings coincide with the socioeconomic inequalities that are prevalent in this country. Mortality rates are higher in the urban centers despite the fact that this is exactly where specialized healthcare is more readily available. No conclusions can be reached concerning the access of these women to diagnosis and treatment, since the coverage of death registration is heterogeneous in the different areas of the country. CONCLUSION: Reductions were found in female breast cancer mortality in five urban centers in Brazil, while increases incurred in most rural areas with the exception of some regions in the south of the country. One of the reasons for this disparity may be the lower access to treatment among patients living in rural areas.

Mammography Screening and Breast Cancer Mortality in Sweden

Swedish women aged 40-69 years were gradually offered regular mammography screening since 1974, and nationwide coverage was achieved in 1997. We hypothesized that this gradual implementation of breast cancer screening would be reflected in county-specific mortality patterns during the last 20 years. Using data from the Swedish Board of Health and Welfare from 1960 to 2009, we used joinpoint regression to analyze breast cancer mortality trends in women aged 40 years and older (1,286,000 women in 1995-1996). Poisson regression models were used to compare observed mortality trends with expected trends if screening had resulted in breast cancer mortality reductions of 10%, 20%, or 30% among women screened during 18 years of follow-up after the introduction of screening. All statistical tests were two-sided. From 1972 to 2009, breast cancer mortality rates in Swedish women aged 40 years and older declined by 0.98% annually, from 68.4 to 42.8 per 100,000, and it continuously declined in 14 of the 21 Swedish counties. In three counties, breast cancer mortality declined sharply during or soon after the implementation of screening; in two counties, a steep decline started at least 5 years after screening was introduced; and in two counties, breast cancer mortality increased after screening started. In counties in which screening started in 1974-1978, mortality trends during the next 18 years were similar to those before screening started, and in counties in which screening started in 1986-1987, mortality increased by approximately 12% (P = .007) after the introduction of screening compared with previous trends. In counties in which screening started in 1987-1988 and in 1989-1990, mortality declined by approximately 5% (P = .001) and 8% (P < .001), respectively, after the introduction of screening. Conclusion County-specific mortality statistics in Sweden are consistent with studies that have reported limited or no impact of screening on mortality from breast cancer.

Disparities in breast cancer mortality trends in a middle income country

In recent decades, breast cancer cases have increased steadily worldwide. However, the increases do not hold across all demographics and breast cancer cases in low and middle income countries have increased much faster than the global trend. Colombia is not an exception. Breast cancer was the most frequent tumor and the second cause of cancer-related deaths in women in 2008, with an estimated of 6,700 new cases and 2,100 deaths. We present here an analysis of breast cancer mortality rates and trends in Colombia, over the period 1985-2008. We studied overall and age-specific changes in breast cancer mortality using change-point Poisson regression models. Between 1985 and 2008, there were 32,375 breast cancer deaths in women in Colombia. Breast cancer mortality increased since 1985, although the annual increase varied between age groups and socioeconomic levels. Only in women aged 45-64 years old that live in areas of high socioeconomic levels, breast cancer mortality was stable or decreasing. Hence, successful cancer control is possible in middle income countries, as shown by the progress observed in certain groups. The development of an integrated strategy of early detection and early access to proper treatment, suitable for areas with limited resources, is an urgent necessity.

E4. Current issues in breast cancer screening

E4. Current issues in breast cancer screening

Increased Trend of Breast Cancer Mortality in Iran

Breast cancer is the most commonly diagnosed cancer in women worldwide In Iran, it ranks first among cancers diagnosed in women and is the fifth most common cause of death. The aim of this study was to present the mortality trends from breast cancer for Iranian women during a period of almost a decade, in order to provide update information regarding the likely future. We analyzed National death Statistic reported by the Iranian Ministry of Health and Medical Education from 1995 to 2004 to generate annual mortality rates/100,000, overall, by age group (<15, 15-49 and ≥ 50 years of age) and age standardized rate (ASR). The age standardized mortality rate of breast cancer increased dramatically during these years from 1.40 to 3.52 per 100,000 and its mortality was increasing 151.4% for Iranian women, although it seemed that the rate leveled off from 2002 to 2004. Moreover the increasing rate was higher for those aged between 15-49 compared to age > 50 years old. There is an increasing trend for breast cancer mortality in Iran. Thus, health education programs to rectify the lack of women awareness about breast cancer signs and effective screening are urgently needed.

High burden of breast cancer in Belgium: recent trends in incidence (1999-2006) and historical trends in mortality (1954-2006).

IntroductionIn Belgium, breast cancer mortality has been monitored since 1954, whereas cancer incidence data have only been made available for a few years. In this article we update historical trends of breast cancer mortality and describe the recent breast cancer incidence.MethodsIncidence data were extracted from the Belgium Cancer Registry from 2004 to 2006 for the Walloon and Brussels Regions and Belgium, and from 1999 to 2006 for the Flemish Region. The Directorate-general Statistics and Economic information provided the mortality data for the years 1954-1999 and 2004. The regional authorities of the Flemish and Brussels Regions provided the mortality data for the years 2000-2003 and 2005-2006.ResultsIn 2004, the World age-standardised breast cancer incidence for the whole of Belgium was 110 per 100, 000 person-years for all ages; and 172, 390 and 345 per 100, 000 person-years for the 35-49, 50-69, and 70+ age groups, respectively. The incidence rate was slightly higher in each age group in the Brussels Region. In Flanders, where the incidence could be observed during a longer period, an increase was observed until 2003 in the 50-69 age group, followed by a decrease. To the contrary, in the oldest age group, incidence continued to rise over the whole period, whereas no change in incidence was observed between 1999 and 2006 in the 35-49 age group.Mortality increased until the late 1980s and afterwards decreased in all regions and in age groups younger than 70. In women of 70 years and older, the decline began later.ConclusionsThe burden of breast cancer in Belgium is very high. In 2004, Belgium ranked first for the age-standardised incidence rate in Europe for all ages combined and in the 35-49 and 50-69 age groups. The impact of the known risk factors and of mammographic screening should be further studied. The mortality rate in Belgium ranked lower than incidence, suggesting favourable survival. Plausible explanations for the discrepancy between incidence and mortality are discussed.

Trends in Breast Cancer Mortality in Sweden before and after Implementation of Mammography Screening

BackgroundIncidence-based mortality modelling comparing the risk of breast cancer death in screened and unscreened women in nine Swedish counties has suggested a 39% risk reduction in women 40 to 69 years old after introduction of mammography screening in the 1980s and 1990s.ObjectiveWe evaluated changes in breast cancer mortality in the same nine Swedish counties using a model approach based on official Swedish breast cancer mortality statistics, robust to effects of over-diagnosis and treatment changes. Using mortality data from the NordCan database from 1974 until 2003, we estimated the change in breast cancer mortality before and after introduction of mammography screening in at least the 13 years that followed screening start.ResultsBreast mortality decreased by 16% (95% CI: 9 to 22%) in women 40 to 69, and by 11% (95% CI: 2 to 20%) in women 40 to 79 years of age.DiscussionWithout individual data it is impossible to completely separate the effects of improved treatment and health service organisation from that of screening, which would bias our results in favour of screening. There will also be some contamination of post-screening mortality from breast cancer diagnosed prior to screening, beyond our attempts to adjust for delayed benefit. This would bias against screening. However, our estimates from publicly available data suggest considerably lower benefits than estimates based on comparison of screened versus non-screened women.

Breast and cervical cancer in 187 countries between 1980 and 2010: a systematic analysis

Breast and cervical cancer are important causes of mortality in women aged ≥15 years. We undertook annual age-specific assessments of breast and cervical cancer in 187 countries. We systematically collected cancer registry data on mortality and incidence, vital registration, and verbal autopsy data for the period 1980-2010. We modelled the mortality-to-incidence (MI) ratio using a hierarchical model. Vital registration and verbal autopsy were supplemented with incidence multiplied by the MI ratio to yield a comprehensive database of mortality rates. We used Gaussian process regression to develop estimates of mortality with uncertainty by age, sex, country, and year. We used out-of-sample predictive validity to select the final model. Estimates of incidence with uncertainty were also generated with mortality and MI ratios. Global breast cancer incidence increased from 641,000 (95% uncertainty intervals 610,000-750,000) cases in 1980 to 1,643,000 (1,421,000-1,782,000) cases in 2010, an annual rate of increase of 3·1%. Global cervical cancer incidence increased from 378,000 (256,000-489,000) cases per year in 1980 to 454,000 (318,000-620,000) cases per year in 2010-a 0·6% annual rate of increase. Breast cancer killed 425,000 (359,000-453,000) women in 2010, of whom 68,000 (62,000-74,000) were aged 15-49 years in developing countries. Cervical cancer death rates have been decreasing but the disease still killed 200,000 (139,000-276,000) women in 2010, of whom 46,000 (33,000-64,000) were aged 15-49 years in developing countries. We recorded pronounced variation in the trend in breast cancer mortality across regions and countries. More policy attention is needed to strengthen established health-system responses to reduce breast and cervical cancer, especially in developing countries. Susan G Komen for the Cure and the Bill & Melinda Gates Foundation.

The decline in breast cancer mortality in Europe: An update (to 2009)

We updated trends in breast cancer mortality in Europe up to the late 2000’s. In the EU, age-adjusted (world standard population) breast cancer mortality rates declined by 6.9% between 2002 and 2006, from 17.9 to 16.7/100,000. The largest falls were in northern European countries, but more recent declines were also observed in central and eastern Europe. In 2007, all major European countries had overall breast cancer rates between 15 and 19/100,000. In relative terms, the declines in mortality were larger at younger age (−11.6% at age 20–49 years between 2002 and 2007 in the EU), and became smaller with advancing age (−6.6% at age 50–69, −5.0% at age 70–79 years). The present report confirms and further quantifies the persisting steady fall in breast cancer mortality in Europe over the last 25–30 years, which is mainly due to advancements in the therapy.

Breast cancer mortality in neighbouring European countries with different levels of screening but similar access to treatment: trend analysis of WHO mortality database

Objective To compare trends in breast cancer mortality within three pairs of neighbouring European countries in relation to implementation of screening.Design Retrospective trend analysis.Setting Three country pairs (Northern Ireland (United...

Regional patterns and time trends in breast cancer mortality among women in China.

e12016 Background: Breast cancer is one of the leading causes of death in China. There is limited information available from large population-based cancer registries to describe the variability in breast cancer mortality in women by region and over time. Methods: The number of deaths and number of women at risk were obtained from the Third National Mortality Retrospective Sampling Survey (2004-2005). A total of 69 690 241 person-years (py) were accumulated in this study. The time trends in mortality during 1973 to 2005 were assessed using data from this survey as well as two previous surveys known as the First Survey in 1973-1975 and the Second Survey in 1990-1992. These surveys are broadly considered representative of the population in China. Results: The crude mortality rate among female breast cancer patients in China in 2004-2005 was 5.90 per 100 000 py (4112/69 690 241). This ranked the sixth most common cancer death in women, and accounted for 5.90% (4112/69 667) of all female cancer deaths. The crude mortality rates among female breast cancer patients were 6.86/100 000 py (1777/25 900 856) in Eastern China, 5.91/100 000 py (1431/24 225 738) in Central China and 4.62/100 000 py (904/19 563 647) in Western China. The age-standardized mortality rate in urban areas (4.91/100 000 py, 1899 deaths) was 1.44 fold higher than that in rural areas (3.42/100 000 py, 2213 deaths). The crude mortality doubled from 2.95/100 000 py in 1973-1975. The age-standardized mortality rate increased from 1.09/100 000 py in 1973-1975 to 3.97/100 000 py in 2004-2005. Conclusions: The mortality rate of female breast cancer in urban areas was higher than in rural areas. The mortality rate was highest in the Eastern region of China, followed by the Central then the Western regions. Breast cancer mortality in women increased substantially in China between 1973 & 2005.

Mortality trends in female breast cancer from 1973 to 2007 in urban Shanghai.

e12015 Background: There is limited published information describing the disease burden of breast cancer in urban Shanghai. Such information is important for planning cancer control and prevention activities. The objective of this analysis was to examine the long-term mortality trends in breast cancer in women from 1973 to 2007 in urban Shanghai. Methods: Female breast cancer deaths and number of women at risk were collected respectively by the Vital Statistics Registry of the Shanghai Center for Disease Control and Prevention and by the Municipal Bureau of Public Security of Shanghai. Time trends in the age-standardized mortality rate of breast cancer in women in urban Shanghai were analyzed using Joinpoint regression modeling including annual percentage change (APC) for both the entire period and for the time segments. Results: A total of 13 285 female breast cancer deaths were registered from 1973 to 2007 in urban Shanghai. The 5-year crude mortality was 18.3 per 100 000 person-years (py) and the age-adjusted mortality was 8.9 per 100 000 py. Breast cancer ranked the fourth leading cause of cancer death among women. From 1973 to 2007, the age-adjusted female breast cancer mortality rate increased consistently in urban Shanghai, with an overall increase of 9.0% and an APC of 0.72% (P<0.001). Conclusions: The observed increasing trend in female breast cancer mortality in urban Shanghai may reflect underlying changes in cancer related risk factors. Currently, risk factors are still widely prevalent. The cancer prevention and control strategies should continue to focus on both common measures for reducing individual exposures and environmental measures.

Trends in breast cancer survival in Germany from 1976 to 2008—A period analysis by age and stage

Background: Implementation of mammography screening and advances in breast cancer treatment are considered as main reasons for the decline in breast cancer mortality observed in many industrialized countries during the past two decades. The purpose of this study was to provide a comprehensive assessment of trends in breast cancer incidence, mortality and survival by age and stage in Germany. Methods: Data from the population based Saarland Cancer Registry including patients diagnosed with breast cancer from 1972 to 2007 were used. Period analysis methods were employed to calculate 5-year relative survival and its trends. Results: Mortality started to decline during the 1990s, and a previous increase in incidence levelled off in the early 21st century. Overall age-standardized 5-year relative survival of invasive breast cancer steadily increased during the past three decades to 83% in 2004–2008. This increase was mostly due to an increase in survival for patients with localized cancers and locally or regionally spread tumours (increase of age-standardized 5-year relative survival from 92% to 98% and from 65% to 80%, respectively, between 1992 and 2008), whereas age-standardized 5-year relative survival essentially remained unchanged at levels close to 21% in patients with metastasized cancer. For women aged 70 years or older 5-year relative survival and its increase over time were inferior compared to younger patients. Conclusions: The observed trends in population based survival suggest that advances in treatment of early breast cancer have substantially contributed to the gain in prognosis. The poor prognosis of metastasized breast cancer patients and the increasing age gradient in 5-year relative survival call for enhanced efforts for early detection and more rigorous treatment of elderly patients.

The Impact of Detection and Treatment of Carcinoma In Situ on Breast Cancer Mortality

Abstract Purpose: Ductal carcinoma in situ (DCIS), a nonobligate precursor to invasive breast cancer, makes up 20% of new breast cancer diagnoses. DCIS is primarily detected by mammography and has excellent prognosis regardless of therapy choice. We aim to quantify the impact of detection and treatment of DCIS on breast cancer mortality using computer modeling. Methods: We used a validated microsimulation model to replicate U.S. trends in breast cancer incidence and mortality from 1975 to 2000. All breast cancer tumors began in the in situ stage and progressed through more advanced stages with increasing tumor size and lymph node involvement, with a fraction of tumors assumed as nonlethal. Age-adjusted breast cancer mortality was examined under historical U.S. screening and treatment patterns and three alternative scenarios: (1) only women 50 years and older received screening and all breast cancer cases received treatment according to historical patterns, (2) all women received screening according to historical patterns but DCIS was untreated unless later detected at an invasive stage, and (3) historical screening was used but DCIS was never treated. Results: The model predicts breast cancer mortality rates declined during the 1990s to a low of 39.9 per 100,000 in 2000, which is consistent with observed mortality based on the SEER program (38.0 per 100,000 in 2000). Delaying mammography until age 50 or postponing treatment until DCIS progressed to invasive cancer increased mortality to 42.4 and 43.2 per 100,000, respectively, by 2000. If DCIS patients did not receive any treatment, mortality remained steady (∼51.2 per 100,000) through 2000. Conclusions: Our model results suggested detection and treatment of DCIS in the U.S. reduced breast cancer deaths in the year 2000 by about 28%. Most of this benefit (92%–94%) could also be achieved if instead mammography began at age 50 or treatment was reserved for invasive breast cancers only.