The benefits and harms of breast cancer screening: an independent review

Blood-based DNA methylation as biomarker for breast cancer: a systematic review

Multiple studies have investigated global DNA methylation profiles and gene-specific DNA methylation in blood-based DNA to develop powerful screening markers for cancer. This systematic review summarizes the current evidence on methylation studies that investigated methylation level of blood-derived DNA of breast cancer (BC) patients in comparison to healthy controls by conducting a systematic literature review in PubMed and Web of Science. Essential results, such as methylation levels of BC cases and healthy controls, p values, and odds ratios, were extracted from these studies by two investigators independently. Overall, 45 publications met the inclusion criteria for this review. DNA from whole blood, as well as cell-free DNA (cfDNA) from serum or plasma, was used in these studies. The most common method used for measuring global DNA methylation was the investigation of repetitive elements as surrogates and the application of array-based genome-wide methylation analysis. For measuring gene-specific methylation level, methylation-specific PCR and pyrosequencing were the most frequently used methods. Epigenome-wide blood DNA hypomethylation in BC patients were reported in several studies; however, the evidence is still not conclusive. The most frequently investigated gene in whole blood was BRCA1, which was found more frequently methylated in patients compared to controls. RASSF1A was the most widely investigated gene in cfDNA of serum or plasma, which was also found more frequently methylated in patients compared to controls. Several of the eligible studies reported the associations of global hypomethylation and increased BC risk. Studies investigated associations between gene-specific methylation and BC risk, while got heterogeneous results. But two studies reported that hypermethylation of ATM gene was associated with increased BC risk, which suggest the potential use of this gene for BC risk stratification. Overall, our review suggests the possibility of using blood-based DNA methylation marker as promising marker for BC risk stratification, as several studies found associations between certain methylation level in blood and BC risk. However, so far, the evidence is still quite limited. Optimal markers are yet to be developed and promising results needed to be validated in prospective study cohorts and tested in large screening populations.

Radiation risk of breast screening in England with digital mammography

OBJECTIVE

To estimate the risks and benefits of breast screening in terms of number of deaths due to radiation-induced cancers and the number of lives saved owing to modern screening in the National Health Service Breast Screening Programme (NHSBSP) in England.

METHODS

Radiation risk model, patient dose data and data from national screening statistics were used to estimate the number of deaths due to radiation-induced breast cancers in the NHSBSP in England. Dose and dose effectiveness factors (DDREFs) equal to one and two were assumed. The breast cancer mortality reduction in the invited population due to screening and the percentage of females diagnosed with symptomatic breast cancer, who die from breast cancer, were collated from the literature. The number of lives saved owing to screening was calculated.

RESULTS

Assuming, a total of 1,770,436 females between the ages of 50-70 years were screened each year, and a breast cancer mortality reduction of 20% due to screening in the invited population, the number of screen-detected cancers were 14,872 annually, resulting in 1071 lives saved. Conversely, for the same mortality reduction, the number of radiation-induced cancers was 36 and 18 for DDREFs of 1 and 2, respectively. This resulted in seven and three deaths due to radiation-induced cancers annually for DDREFs of 1 and 2, respectively. The ratios of lives saved owing to screening to radiation-induced cancers were 30 : 1 and 60 : 1 for DDREFs of 1 and 2. The ratios of lives saved owing to screening to deaths due to radiation-induced cancers were 156 : 1 and 312 : 1 for DDREFs of 1 and 2. For the 1.8% of the screening population with very thick breasts, the latter ratios decrease to 94 : 1 and 187 : 1 for DDREFs of 1 and 2.

CONCLUSION

The breast cancer mortality reduction due to screening greatly outweighs the risk of death due to radiation-induced cancers. Advances in knowledge: Estimation of the radiation risk for modern breast screening in England using digital mammography.

Breast cancer incidence trends in Norway and estimates of overdiagnosis

Objective

Fluctuations in the incidence of breast cancer in Norway in the last three decades are partly explained by the use of hormone replacement therapy and mammography screening, but overdiagnosis has also been suggested as a cause. We assessed the trends in breast cancer incidence and overdiagnosis in Norway.

Methods

We calibrated our microsimulation model to Norwegian Cancer Registration data. The model takes into account the use of mammography (both within and outside the Norwegian Breast Cancer Screening Programme) and of hormone replacement therapy. We obtained a proper fit of breast cancer incidence in recent years, when assuming an increase in the background risk for breast cancer, and estimated overdiagnosis.

Results

We estimated a 2% overdiagnosis rate as a fraction of all cancers diagnosed in women aged 50–100, and a 3% overdiagnosis rate as a fraction of all cancers diagnosed in women aged 50–70 (i.e. screening age). If all of the increased incidence would be the result of the detection of slow growing tumours, these estimates were 7% and 11%, respectively.

Conclusion

Besides mammography and hormone replacement therapy use, additional risk factors contributed to the sudden increase in breast cancer incidence in Norway. Overdiagnosis estimates due to screening were within the range of international plausible estimates.

Microcalcification on mammography: approaches to interpretation and biopsy

This article discusses the significance of microcalcifications on mammography and the changes in technology that have influenced management; it also describes a pragmatic approach to investigation of microcalcification in a UK screening programme.

Rapid review of evaluation of interventions to improve participation in cancer screening services

Objective

Screening participation is spread differently across populations, according to factors such as ethnicity or socioeconomic status. We here review the current evidence on effects of interventions to improve cancer screening participation, focussing in particular on effects in underserved populations.

Methods

We selected studies to review based on their characteristics: focussing on population screening programmes, showing a quantitative estimate of the effect of the intervention, and published since 1990. To determine eligibility for our purposes, we first reviewed titles, then abstracts, and finally the full paper. We started with a narrow search and expanded this until the search yielded eligible papers on title review which were less than 1% of the total. We classified the eligible studies by intervention type and by the cancer for which they screened, while looking to identify effects in any inequality dimension.

Results

The 68 papers included in our review reported on 71 intervention studies. Of the interventions, 58 had significant positive effects on increasing participation, with increase rates of the order of 2%–20% (in absolute terms).

Conclusions

Across different countries and health systems, a number of interventions were found more consistently to improve participation in cancer screening, including in underserved populations: pre-screening reminders, general practitioner endorsement, more personalized reminders for non-participants, and more acceptable screening tests in bowel and cervical screening.

Specific Aspects of Breast Cancer Therapy of Elderly Women

Breast cancer is the leading cause of death among women, and its incidence increases with age. The average age at diagnosis is 61 years, and the majority of deaths occurs after the age of 65 years. Optimal approach to elderly women with breast cancer is still a major challenge. Elderly patients with cancer should have at least a brief geriatric assessment to detect potentially treatable problems not always adequately evaluated by the oncologists. Therapeutic nihilism should be avoided and effective treatment provided, unless there are compelling reasons against it. Sharing the care for the patient with geriatricians or primary care physicians trained in geriatrics should be considered for all vulnerable and frail elderly patients.

Exploring breast health practices of post-menopausal women: Implications to informed consent

In light of the contention surrounding breast health practices, the research aimed to explore post-menopausal women's experiences of such practices. Semi-structured interviews were conducted in July and August 2015 with 13 Australian women aged 54-74 years. Data were analysed thematically. Participants deemed their engagement with breast health practices as the 'right' thing. However, engaging in these 'right' practices appeared to be fostered by misconceptions. The findings suggest that women may not be making evidence-informed decisions to engage in breast screening; identify contemporary barriers to promoting informed decisions; and may inform information pertinent to breast screening policy, campaigns and decision aid designs.

Cause-specific mortality in women with breast cancer in situ

The long-term mortality remains unknown in women diagnosed with breast cancer in situ (BCIS). Here, we assessed the cause-specific mortality in BCIS patients. This population-based cohort study included 12,243 women diagnosed with BCIS in Sweden between 1980 and 2011. Patients were followed until death, emigration, or 31 December 2013, whichever came first. The 30-year cumulative incidence of breast cancer-specific mortality was 6.3%, which is considerably lower than 49.7% observed for other-cause mortality. Women diagnosed with BCIS were more likely to die from breast cancer (standardized mortality ratio [SMR], 3.85; 95% CI, 3.47-4.27) but less likely to die from cardiovascular disease (SMR, 0.88; 95% CI, 0.82-0.95) than women in the general population. Specifically, the SMRs for breast cancer-specific mortality decreased over time from 5.19 (95% CI, 3.95-6.81) among BCIS diagnosed during 1980-1989 to 3.03 (95% CI, 2.35-3.91) among those diagnosed during 2000-2011. Furthermore, higher risk of death from other causes was seen among those with older age at BCIS diagnosis, lower levels of education, nulliparity, higher Charlson Comorbidity Index, and being hospitalized before BCIS diagnosis; whereas, lower risk of death from breast cancer was seen among BCIS diagnosed in the later time period and those with younger age at first birth. We conclude that most women diagnosed with BCIS die from causes other than breast cancer, which highlights the need for actions not only to reduce nonbreast cancer mortality but also to identify patient where extensive curative BCIS treatment is not adding to survival.

Preliminary results of a new approach for three-dimensional reconstruction of Dynamic AngioThermography (DATG) images based on the inversion of heat equation

Dynamic AngioThermography (DATG) is a contact-plate technique capable of producing a digital representation of breast vascularity. The inception and growth of a tumor are associated with neoangenesis, which may result in a demonstrable alteration in the regional blood flow, while in normal health conditions the vascularity remains unchanged throughout life. DATG, if included in the clinical evaluation for breast cancer, could potentially improve the accuracy of the diagnosis of this disease. Conventional DATG is limited, however, in that it is a projection (i.e. two-dimensional) imaging technique that does not provide any information on the depth and its effect on the pattern of the perfusion revealed by this technique. In fact, the blood pattern is detected by projecting temperature signals on the plate, thus acquiring a digital two-dimensional image. In this article we propose a new approach for extracting information on depth through the inversion of the Fourier heat equation. The idea is to extract the information along the third axis while acquiring and analyzing the temporal sequence during the process of image formation. The method implemented has been tested on a dedicated "electric phantom" and in one in vivo experiment. In spite of the limits of these preliminary tests, the experimental results have shown that this method makes it possible to obtain a 3D representation of the vascularity. Although it appears to be promising, further validation and characterization of our technique are required.

Potential biomarker panels in overall breast cancer management: advancements by multilevel diagnostics

Breast cancer (BC) prevalence has reached an epidemic scale with half a million deaths annually. Current deficits in BC management include predictive and preventive approaches, optimized screening programs, individualized patient profiling, highly sensitive detection technologies for more precise diagnostics and therapy monitoring, individualized prediction and effective treatment of BC metastatic disease. To advance BC management, paradigm shift from delayed to predictive, preventive and personalized medical services is essential. Corresponding step forwards requires innovative multilevel diagnostics procuring specific panels of validated biomarkers. Here, we discuss current instrumental advancements including genomics, proteomics, epigenetics, miRNA, metabolomics, circulating tumor cells and cancer stem cells with a focus on biomarker discovery and multilevel diagnostic panels. A list of the recommended biomarker candidates is provided.

Mammographic density and structural features can individually and jointly contribute to breast cancer risk assessment in mammography screening: a case-control study

Background

Mammographic density is a well-established risk factor for breast cancer. We investigated the association between three different methods of measuring density or parenchymal pattern/texture on digitized film-based mammograms, and examined to what extent textural features independently and jointly with density can improve the ability to identify screening women at increased risk of breast cancer.

Methods

The study included 121 cases and 259 age- and time matched controls based on a cohort of 14,736 women with negative screening mammograms from a population-based screening programme in Denmark in 2007 (followed until 31 December 2010). Mammograms were assessed using the Breast Imaging-Reporting and Data System (BI-RADS) density classification, Tabár’s classification on parenchymal patterns and a fully automated texture quantification technique. The individual and combined association with breast cancer was estimated using binary logistic regression to calculate Odds Ratios (ORs) and the area under the receiver operating characteristic (ROC) curves (AUCs).

Results

Cases showed significantly higher BI-RADS and texture scores on average than controls (p < 0.001). All three methods were individually able to segregate women into different risk groups showing significant ORs for BI-RADS D3 and D4 (OR: 2.37; 1.32–4.25 and 3.93; 1.88–8.20), Tabár’s PIII and PIV (OR: 3.23; 1.20–8.75 and 4.40; 2.31–8.38), and the highest quartile of the texture score (3.04; 1.63–5.67). AUCs for BI-RADS, Tabár and the texture scores (continuous) were 0.63 (0.57–0–69), 0.65 (0.59–0–71) and 0.63 (0.57–0–69), respectively. Combining two or more methods increased model fit in all combinations, demonstrating the highest AUC of 0.69 (0.63-0.74) when all three methods were combined (a significant increase from standard BI-RADS alone).

Conclusion

Our findings suggest that the (relative) amount of fibroglandular tissue (density) and mammographic structural features (texture/parenchymal pattern) jointly can improve risk segregation of screening women, using information already available from normal screening routine, in respect to future personalized screening strategies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2450-7) contains supplementary material, which is available to authorized users.

Designing Radiology Outcomes Studies-Essential Principles

Health outcomes research is essential to align radiology with current standards of high-value patient care, through the assessment of end results of diagnostic tests, interventions, or policy on patient health. To bridge studies of diagnostic test accuracy and health outcomes research, key considerations include: (1) how to determine when a diagnostic test merits evaluation of impact on outcomes, (2) when study of intermediate/surrogate outcomes can be useful, (3) how to consider the possible harms as well as potential benefits of a test, and (4) how to integrate evidence of an imaging test's efficacy/effectiveness with clinical data to assess outcomes. Due to challenges in conducting studies of long-term outcomes consequent to imaging use, intermediate health outcomes may capture a test's impact on successful diagnosis and therapy, and can provide readily measurable, incremental insights into the role of imaging in health-care delivery and efficiency. In an era marked by recognition of quality and value of care, outcomes research will provide essential evidence to inform radiologists' guidance of imaging use toward improved patient care, creation of clinical guidelines, and policy decisions.

Breast Density Knowledge and Awareness: A Review of Literature

OBJECTIVES

We reviewed the literature on breast density knowledge and breast density awareness to explore what challenges are faced by this area of research.

METHOD

A review of PubMED, PsycINFO, and CINAHL databases was performed. Studies were published in peer-reviewed journals (in all years available) and written in English. The broad search terms used were ["breast density"] AND ["knowledge" OR "awareness"]. Eligible articles were included in the final analysis after meeting the following inclusion criteria: (1) the records had to quantitatively examine and report breast density knowledge and awareness, (2) the number of participants in the sample had to be clearly specified, and (3) studies reporting differences in breast density knowledge and awareness between racial and ethnic groups were included in the review.

RESULTS

Of the 277 articles identified, only 5 met inclusion criteria and addressed breast density knowledge and awareness. Characteristics of studies and results were examined.

CONCLUSIONS

There is insufficient evidence to determine a pattern of breast density knowledge and awareness in women. More quality studies are needed that focus on how well women understand the relationship between breast density, breast cancer risk, and breast cancer screening, especially in diverse populations.

Proportion of women with self-reported opportunistic mammography before organized screening

BACKGROUND

In Finland, organized nationwide breast cancer (BC) screening is biennially offered for women aged 50-69 years. The aim was to estimate, for the first time in Finland, the proportion of women having opportunistic mammography at age less than 50 years and to investigate the role of BC family history and educational level for having opportunistic mammography.

MATERIAL AND METHODS

The study material comprises two self-administered, population-based questionnaires from altogether 9845 healthy women; 4666 women in Women's Health and Use of Hormone-study (WHH survey), and 5179 in Breast Cancer Screening, Lifestyle and Quality of Life-study (EET survey). We report the estimated proportions of women with self-reported opportunistic mammography at age <50 years in percentages.

RESULTS

The response percentages were 53% in the WHH survey and 52% in the EET survey. The percentage of women with self-reported opportunistic mammography was 66.7% and 60.4% in the two questionnaires, respectively. Regarding family history of BC, 76.5% and 68.5% of women with BC family history in a first degree relative reported having had a mammography, in contrast to that of 65.5% and 59.4% of women without BC family history. Opportunistic mammography was also more common in women with >12 years of education than women with ≤12 years of education.

DISCUSSION AND CONCLUSIONS

Overall, some two thirds of the women reports of having had a mammography before organized screening started. Opportunistic mammography was more likely among women with a positive family history of BC in a first degree relative as well as more than 12 years of education. Regardless of low response activity, the observed popularity of opportunistic mammography before organized screening gives ground for further evaluation of the related health care practices. Screening activity before organized screening also influences the evaluation of the screening program, as women have different, indeterminate histories of pre-organized screening.

The role of pre-invasive disease in overdiagnosis: A microsimulation study comparing mass screening for breast cancer and cervical cancer

Objective

Although early detection of cancer through screening can prevent cancer deaths, a drawback of screening is overdiagnosis. Overdiagnosis has been much debated in breast cancer screening, but less so in cervical cancer screening. We examined the impact of overdiagnosis by comparing two screening programmes in the Netherlands.

Methods

We estimated overdiagnosis rates by microsimulation for breast cancer screening and cervical cancer screening, using a cohort of women born in 1982 with lifelong follow-up. Overdiagnosis estimates were made analogous to two definitions formed by the UK 2012 breast screening review. Pre-invasive disease was included in both definitions.

Results

Screening prevented 921 cervical cancers (−55%) and 378 cervical cancer deaths (−59%), and 169 (−1.3%) breast cancer cases and 970 breast cancer deaths (−21%). The cervical cancer overdiagnosis rate was 74.8% (including pre-invasive disease). Breast cancer overdiagnosis was estimated at 2.5% (including pre-invasive disease). For women of all ages in breast cancer screening, an excess of 207 diagnoses/100,000 women was found, compared with an excess of 3999 diagnoses/100,000 women in cervical cancer screening.

Conclusions

For breast cancer, the frequency of overdiagnosis in screening is relatively low, but consequences are evident. For cervical cancer, the frequency of overdiagnosis in screening is high, because of detection of pre-invasive disease, but the consequences per case are relatively small due to less invasive treatment. This illustrates that it is necessary to present overdiagnosis in relation to disease stage and consequences.

How Can Advanced Imaging Be Used to Mitigate Potential Breast Cancer Overdiagnosis?

Radiologists, as administrators and interpreters of screening mammography, are considered by some to be major contributors to the potential harms of screening, including overdiagnosis and overtreatment. In this article, we outline current efforts within the breast imaging community toward mitigating screening harms, including the widespread adoption of tomosynthesis and potentially adjusting screening frequency and thresholds for image-guided breast biopsy. However, the emerging field of breast radiomics may offer the greatest promise for reducing overdiagnosis by identifying imaging-based biomarkers strongly associated with tumor biology, and therefore helping prevent the harms of unnecessary treatment for indolent cancers.

Implementation of the German Mammography Screening Program (German MSP) and First Results for Initial Examinations, 2005-2009

BACKGROUND

The German Mammography Screening Program (German MSP) is population-based and intended for women aged 50-69 years (approximately 10.5 million). The program started in 2005 and was implemented within 5 years. This article describes the implementation, structure, and screening process, and presents the results of initial examinations for the prevalence phase.

METHODS

Data were collected annually from invitation centers (invitation, attendance), screening units (performance, outcomes), and cancer registries (incidence).

RESULTS

In 2009, 92% of all annually eligible women were invited; 50% of the annually eligible population participated. The total cancer detection rate in the period of 2005-2009 was 8.1/1,000; the corresponding recall rate was 5.9%. 19.6% of detected cancers were ductal carcinoma in situ; 76.7% of invasive cancers were ≤ 20 mm in size, 30.2% were ≤ 10 mm, and 75.3% were node-negative. During the implementation period, incidence increased by 37 and 56% in the old and new federal states, respectively. Incidence rates decreased following the prevalence phase.

CONCLUSION

The German MSP was successfully implemented. The results of the prevalence phase meet the target values of the European guidelines. Proper functioning of the program is also verified by its effects on breast cancer incidence. To draw reliable conclusions regarding the long-term effects of the program, results from the routine screening rounds have to be awaited.

Overdiagnosis and overtreatment associated with breast cancer mammography screening: A simulation study with calibration to population-based data

OBJECTIVES

The magnitude of overdiagnosis of breast cancer associated with mammography screening remains controversial because of methodological issues. The objective of this study was to quantify overdiagnosis and overtreatment associated with a population-based screening programme, taking into account lead time and uncertainty concerning baseline incidence of breast cancers.

MATERIAL AND METHODS

A simulation model was developed to replicate incidence and detection rates of breast cancer observed in the Isère Département, France. The parameters of the model were estimated using an approximate Bayesian computation method.

RESULTS

For women aged 50-74 years during the 2007-2010 period, overdiagnosis of non-progressive breast cancers accounted for 17.0% (95% credibility interval (CI): 2.5%-35.5%) of all in situ cancers diagnosed, 5.5% (95% CI: 0.8%-9.8%) of all invasive cancers diagnosed, and 20.3% (95% CI: 3.0%-38.9%) of in situ and 13.0% (95% CI: 2.2%-23.3%) of invasive screen detected breast cancers. The estimates of overdiagnosis due to competitive causes of death were 1.0% (95% CI: 0.2%-%1.7) and 1.1% (95% CI: 0.6%-1.7%) for all in situ and invasive cancers diagnosed, respectively, and 1.3% (95% CI: 0.2%-2.0%) and 2.6% (95% CI: 1.4%-4.0%) of all in situ and invasive screen detected breast cancers, respectively. Among 1000 screen-detected cancers in 2010, 155 (95% CI: 27-284), 134 (95% CI: 10-242) and 140 (95% CI: 25-254) women underwent breast conserving surgery, lymph node dissection and radiation therapy for overdiagnosed cancers, respectively.

CONCLUSION

Our estimates of overdiagnosis should be balanced against the reduction of breast cancer mortality to assess the value of breast cancer screening programme.

Meta-analysis of breast cancer mortality benefit and overdiagnosis adjusted for adherence: improving information on the effects of attending screening mammography

BACKGROUND

Women require information about the impact of regularly attending screening mammography on breast cancer mortality and overdiagnosis to make informed decisions. To provide this information we aimed to meta-analyse randomised controlled trials adjusted for adherence to the trial protocol.

METHODS

Nine screening mammography trials used in the Independent UK Breast Screening Report were selected. Extending an existing approach to adjust intention-to-treat (ITT) estimates for less than 100% adherence rates, we conducted a random-effects meta-analysis. This produced a combined deattenuated prevented fraction and a combined deattenuated percentage risk of overdiagnosis.

RESULTS

In women aged 39-75 years invited to screen, the prevented fraction of breast cancer mortality at 13-year follow-up was 0.22 (95% CI 0.15-0.28) and it increased to 0.30 (95% CI 0.18-0.42) with deattenuation. In women aged 40-69 years invited to screen, the ITT percentage risk of overdiagnosis during the screening period was 19.0% (95% CI 15.2-22.7%), deattenuation increased this to 29.7% (95% CI 17.8-41.5%).

CONCLUSIONS

Adjustment for nonadherence increased the size of the mortality benefit and risk of overdiagnosis by up to 50%. These estimates are more appropriate when developing quantitative information to support individual decisions about attending screening mammography.

Socioeconomic inequalities in breast cancer incidence and mortality in Europe-a systematic review and meta-analysis

Background: Breast cancer is the leading cause of female cancer in Europe and is estimated to affect more than one in 10 women. Higher socioeconomic status has been linked to higher incidence but lower case fatality, while the impact on mortality is ambiguous. Methods: We performed a systematic literature review and meta-analysis on studies on association between socioeconomic status and breast cancer outcomes in Europe, with a focus on effects of confounding factors. Summary relative risks (SRRs) were calculated. Results: The systematic review included 25 articles of which 8 studied incidence, 10 case fatality and 8 mortality. The meta-analysis showed a significantly increased incidence (SRR 1.25, 1.17–1.32), a significantly decreased case fatality (SRR 0.72, 0.63–0.81) and a significantly increased mortality (SRR 1.16, 1.10–1.23) for women with higher socioeconomic status. The association for incidence became insignificant when reproductive factors were included. Case fatality remained significant after controlling for tumour characteristics, treatment factors, comorbidity and lifestyle factors. Mortality remained significant after controlling for reproductive factors. Conclusion: Women with higher socioeconomic status show significantly higher breast cancer incidence, which may be explained by reproductive factors, mammography screening, hormone replacement therapy and lifestyle factors. Lower case fatality for women with higher socioeconomic status may be partly explained by differences in tumour characteristics, treatment factors, comorbidity and lifestyle factors. Several factors linked to breast cancer risk and outcome, such as lower screening attendance for women with lower socioeconomic status, are suitable targets for policy intervention aimed at reducing socioeconomic-related inequalities in health outcomes.

The distribution of ductal carcinoma in situ (DCIS) grade in 4232 women and its impact on overdiagnosis in breast cancer screening

BACKGROUND

The incidence of ductal carcinoma in situ (DCIS) has rapidly increased over time. The malignant potential of DCIS is dependent on its differentiation grade.

METHODS

Our aim is to determine the distribution of different grades of DCIS among women screened in the mass screening programme, and women not screened in the mass screening programme, and to estimate the amount of overdiagnosis by grade of DCIS. We retrospectively included a population-based sample of 4232 women with a diagnosis of DCIS in the years 2007-2009 from the Nationwide network and registry of histopathology and cytopathology in the Netherlands. Excluded were women with concurrent invasive breast cancer, lobular carcinoma in situ and no DCIS, women recently treated for invasive breast cancer, no grade mentioned in the record, inconclusive record on invasion, and prevalent DCIS. The screening status was obtained via the screening organisations. The distribution of grades was incorporated in the well-established and validated microsimulation model MISCAN.

RESULTS

Overall, 17.7 % of DCIS were low grade, 31.4 % intermediate grade, and 50.9 % high grade. This distribution did not differ by screening status, but did vary by age. Older women were more likely to have low-grade DCIS than younger women. Overdiagnosis as a proportion of all cancers in women of the screening age was 61 % for low-grade, 57 % for intermediate-grade, 45 % for high-grade DCIS. For women age 50-60 years with a high-grade DCIS this overdiagnosis rate was 21-29 %, compared to 50-66 % in women age 60-75 years with high-grade DCIS.

CONCLUSIONS

Amongst the rapidly increasing numbers of DCIS diagnosed each year is a significant number of overdiagnosed cases. Tailoring treatment to the probability of progression is the next step to preventing overtreatment. The basis of this tailoring could be DCIS grade and age.

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

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

Retrospective Studies: A Fresh Look

PURPOSE

A first objective was to provide an overview of advantages and cautions around so-called retrospective clinical studies. A second objective was to provide guidelines for strong studies that can make a valid contribution to the clinical literature, whether these studies are prospective, retrospective, experimental, or observational.

METHOD

Invited commentaries were solicited from statistical and study design experts.

RESULTS

The strength of a clinical study does not lie so much with its point in time relative to data generation, as it lies with study design. In fact, quite surprisingly, data collected in the past can be modeled to create a prospective study, if appropriate. One distinctive strength of observational studies-which are sometimes but not always retrospective-is the ability to obtain a large corpus of data from medical databases rapidly, as sometimes warranted by pressing health care policy and practice issues.

CONCLUSION

Retrospective studies, often considered inferior to prospective, randomized, and controlled clinical trials, can have strength and validity often not recognized in the hierarchy of clinical data.

Impact of Screening on Breast Cancer Mortality: The UK Program 20 Years On

BACKGROUND

With changes in diagnosis, treatment, and management of breast cancer since the mammography screening trials, there is a need to evaluate contemporary breast screening programs. A case-control study was set up to assess the current impact of attendance in the English Breast Screening Program on breast cancer mortality.

METHODS

Cancer registry cases who died from primary breast cancer ages 47 to 89 years in London in 2008 to 2009 (869 women) were matched to 1 or 2 general population controls (1,642 women) with no diagnosis of breast cancer at the time of the case's diagnosis, who were alive at the case's death. Cases and controls were matched for date of birth and screening area, and had been invited to breast screening at least once prior to the case's diagnosis. ORs were estimated using conditional logistic regression. Self-selection bias was addressed using contemporaneous attendance at the cervical screening program. Sensitivity analyses were undertaken to assess the likely effect of lead time bias.

RESULTS

Attendance at breast screening resulted in a breast cancer mortality reduction of 39% [OR, 0.61; 95% confidence interval (CI), 0.44-0.85] after self-selection correction. Attendance in the last 3 years prior to diagnosis resulted in a 60% mortality reduction (OR, 0.40; 95% CI, 0.31-0.51). Lead time bias effects were negligible.

CONCLUSION

Our results suggest that community breast screening programs provide their expected benefit in terms of reducing the risk of breast cancer death among women participating.

IMPACT

Mammography is an important tool for reducing breast cancer mortality and its impact could be increased by encouraging regular attendance.

Explaining the Better Prognosis of Screening-Exposed Breast Cancers: Influence of Tumor Characteristics and Treatment

BACKGROUND

In England, population mammographic screening has been offered to women for over 20 years. Overall decrease in breast cancer mortality rates and improvements in cancer awareness and organization of medical care over this period call for a more current evaluation of the mediators behind the better prognosis of screening-exposed breast cancers.

METHODS

A case-control study was conducted within the English National Breast Screening Program. Women who died from primary breast cancer in 2008 to 2009 were matched (by year of birth, screening invitation, and area) to controls that received a diagnosis of invasive breast cancer at the time of the case diagnosis but survived the case death. Data were analyzed by unconditional logistic regression with adjustment for matching factors.

RESULTS

The unadjusted OR for dying from breast cancer associated with ever having attended breast screening was 0.44 [95% confidence interval (CI), 0.33-0.58]. After adjustment for lead time, overdiagnosis, and self-selection, the OR increased to 0.69 (95% CI, 0.50-0.94). Adjusting for tumor size, lymph node status, stage, grade, histopathology, and laterality accounted for all the screening effect (OR, 1.00; 95% CI, 0.71-1.40). Further adjustment for treatment factors only had a minimal impact on the OR (OR, 1.02; 95% CI, 0.72-1.45).

CONCLUSIONS

Our results suggest that earlier diagnosis, as reflected by tumor characteristics, remains the major mediator of the improvement in breast cancer survival due to participation in mammographic screening.

IMPACT

Mammographic screening continues to prevent breast cancer-related deaths in the epoch of adjuvant systemic therapy.

Cancer screening in the United States, 2016: A review of current American Cancer Society guidelines and current issues in cancer screening

Each year the American Cancer Society (ACS) publishes a summary of its guidelines for early cancer detection, data and trends in cancer screening rates, and select issues related to cancer screening. In this issue of the journal, we summarize current ACS cancer screening guidelines, including the update of the breast cancer screening guideline, discuss quality issues in colorectal cancer screening and new developments in lung cancer screening, and provide the latest data on utilization of cancer screening from the National Health Interview Survey.

Optimal therapy for polycythemia vera and essential thrombocythemia: Preferred use of interferon therapy based on phase 2 trials

OBJECTIVES

To determine the value of recombinant interferon-alfa (rIFNα) in the treatment of polycythemia vera (PV) and essential thrombocythemia (ET) based on its biological activities and phase 2 clinical studies, pending completion of phase 3 trials; to determine importance of the Internet in patient decision-making in treatment selection.

RESULTS

The value of rIFNα in PV and ET is based upon its biological effects on PV stem cells and megakaryocyte proliferation. Single-arm trials are useful for life-threatening diseases when there are relatively few patients to evaluate endpoints, such as rIFNα treatment of PV and ET. Proper diagnostic criteria are mandatory; for PV, the current World Health Organization criteria emphasizing increased hemoglobin values exclude approximately one-third of eligible patients. Importance of these data: Single-arm studies in diseases exemplified by rIFNα in PV require updated diagnostic criteria for research and for clinical practice. The influence of the Internet on patient decisions for treatment is noteworthy.

CONCLUSION

The biologic basis for selecting therapy is exemplified by rIFNα in treating PV and ET. Current single-arm studies of rIFNα in PV and ET are relevant and acceptable. The importance of the Internet in patient decision-making is important.

Harms of Breast Cancer Screening: Systematic Review to Update the 2009 U.S. Preventive Services Task Force Recommendation

BACKGROUND

In 2009, the U.S. Preventive Services Task Force recommended biennial mammography screening for women aged 50 to 74 years and selective screening for those aged 40 to 49 years.

PURPOSE

To review studies of screening in average-risk women with mammography, magnetic resonance imaging, or ultrasonography that reported on false-positive results, overdiagnosis, anxiety, pain, and radiation exposure.

DATA SOURCES

MEDLINE and Cochrane databases through December 2014.

STUDY SELECTION

English-language systematic reviews, randomized trials, and observational studies of screening.

DATA EXTRACTION

Investigators extracted and confirmed data from studies and dual-rated study quality. Discrepancies were resolved through consensus.

DATA SYNTHESIS

Based on 2 studies of U.S. data, 10-year cumulative rates of false-positive mammography results and biopsies were higher with annual than biennial screening (61% vs. 42% and 7% vs. 5%, respectively) and for women aged 40 to 49 years, those with dense breasts, and those using combination hormone therapy. Twenty-nine studies using different methods reported overdiagnosis rates of 0% to 54%; rates from randomized trials were 11% to 22%. Women with false-positive results reported more anxiety, distress, and breast cancer-specific worry, although results varied across 80 observational studies. Thirty-nine observational studies indicated that some women reported pain during mammography (1% to 77%); of these, 11% to 46% declined future screening. Models estimated 2 to 11 screening-related deaths from radiation-induced cancer per 100,000 women using digital mammography, depending on age and screening interval. Five observational studies of tomosynthesis and mammography indicated increased biopsies but reduced recalls compared with mammography alone.

LIMITATIONS

Studies of overdiagnosis were highly heterogeneous, and estimates varied depending on the analytic approach. Studies of anxiety and pain used different outcome measures. Radiation exposure was based on models.

CONCLUSION

False-positive results are common and are higher for annual screening, younger women, and women with dense breasts. Although overdiagnosis, anxiety, pain, and radiation exposure may cause harm, their effects on individual women are difficult to estimate and vary widely.

PRIMARY FUNDING SOURCE

Agency for Healthcare Research and Quality.

Optimal breast cancer screening strategies for older women: current perspectives

Breast cancer is a major cause of cancer-related deaths among older women, aged 65 years or older. Screening mammography has been shown to be effective in reducing breast cancer mortality in women aged 50–74 years but not among those aged 75 years or older. Given the large heterogeneity in comorbidity status and life expectancy among older women, controversy remains over screening mammography in this population. Diminished life expectancy with aging may decrease the potential screening benefit and increase the risk of harms. In this review, we summarize the evidence on screening mammography utilization, performance, and outcomes and highlight evidence gaps. Optimizing the screening strategy will involve separating older women who will benefit from screening from those who will not benefit by using information on comorbidity status and life expectancy. This review has identified areas related to screening mammography in older women that warrant additional research, including the need to evaluate emerging screening technologies, such as tomosynthesis among older women and precision cancer screening. In the absence of randomized controlled trials, the benefits and harms of continued screening mammography in older women need to be estimated using both population-based cohort data and simulation models.

A randomised trial of the effect of postal reminders on attendance for breast screening

BACKGROUND

Some women make an informed choice not to attend breast screening, whereas others may have forgotten about the appointment. We report on a randomised trial that investigates whether a reminder letter affects attendance.

METHODS

Women scheduled for a breast screening appointment were randomised to either receive a reminder letter a few days before their breast screening appointment in addition to the standard invitation letter (intervention) or not (control). The primary outcome was attendance within 30 days of the first offered appointment. Secondary outcomes were attendance within 90 and 180 days.

RESULTS

In all, 11,383 (49.9%) women were randomised to the intervention and 11,445 (50.1%) to the control. In the intervention arm, 7759 (68.2%) attended within 30 days of the first offered appointment compared with 7349 (64.2%) in the control arm. This difference was significant (P<0.001). The odds ratio (OR) (95% confidence interval) for the primary end point was 1.19 (1.13-1.26). This was not significantly affected by age, socioeconomic status or type of screen (prevalent or incident). Secondary endpoint analyses supported these results. Results did differ, however, between the different centres studied.

CONCLUSIONS

This study found that postal reminders increase breast screening uptake, and could be practicable to implement in the NHS Breast Screening Programme.

Estradiol, TGF-β1 and hypoxia promote breast cancer stemness and EMT-mediated breast cancer migration

Breast cancer is one of the most common cancer types among women, acting as a distinct cause of mortality, and has a high incidence of recurrence. External stimuli, including 17β-estradiol (E2), transforming growth factor (TGF)-β1 and hypoxia, may be important in breast cancer growth and metastasis. However, the effects of these stimuli on breast cancer stem cell (CSC) regulation have not been fully investigated. In the present study, the proportion of cluster of differentiation (CD)44⁺/CD24^-/low cells increased following treatment with E2, TGF-β1 and hypoxia in MCF-7 cells. The expression of CSC markers, including SOX2, KLF4 and ABCG2, was upregulated continually by E2, TGF-β1 and hypoxia. In addition, the expression levels of epithelial-mesenchymal transition-associated factors increased following treatment with E2, TGF-β1 and hypoxia. Therefore, the migration ability of E2-, TGF-β1- and hypoxia-treated MCF-7 cells was enhanced compared with control cells. In addition, the enhancement of apoptosis by 5-flurouracil or radiation was abolished following treatment with E2, TGF-β1 and hypoxia. These results indicate that E2, TGF-β1 and hypoxia are important for regulating breast CSCs, and that the modulation of the microenvironment in tumors may improve the efficiency of breast cancer therapy.

Trends in UK regional cancer mortality 1991-2007

Background:

Until 1990, there was an upward trend in mortality from breast, lung, prostate, and colon cancers in the United Kingdom. With improvements in cancer treatment there has, in general, been a fall in mortality over the last 20 years. We evaluate regional cancer mortality trends in the United Kingdom between 1991 and 2007.

Methods:

We analysed mortality trends for breast, lung, prostate, and colon cancers using data obtained from the EUREG cancer database. We have described changes in age-standardised rates (using European standard population) per 100 000 for cancer mortality and generated trends in mortality for the 11 regions using Joinpoint regression.

Results:

Across all regions in the United Kingdom there was a downward trend in mortality for the four most common cancers in males and females. Overall, deaths from colon cancer decreased most rapidly and deaths from prostate cancer decreased at the slowest rate. Similar downward trends in mortality were observed across all regions of the United Kingdom with the data for lung cancer exhibiting the greatest variation.

Conclusions:

Mortality from the four most common cancers decreased across all regions of the United Kingdom; however, the rate of decline varied between cancer type and in some instances by region.

Clinical effectiveness of cancer screening biomarker tests offered as self-pay health service: a systematic review

BACKGROUND

Biomarker tests are increasingly being offered by laboratories and clinicians as self-pay health services to screen asymptomatic individuals; however, sufficient evidence may not be available to support this practice. We investigated the benefit-harm tradeoffs associated with 11 biomarkers currently offered in Germany as self-pay tests to screen for cancer.

METHODS

We systematically searched bibliographic databases for health technology assessments, systematic reviews and randomized-controlled trials (RCTs) through September 2015. We included publications that analysed cancer screening biomarkers and reported patient-relevant outcomes (mortality, morbidity, quality of life), and potential harms of screening, among asymptomatic individuals in screening and non-screening arms. Language was restricted to English and German. Two reviewers independently screened references; data were extracted and quality of included studies was evaluated by a reviewer and validated by a second reviewer.

RESULTS

Six publications of secondary literature and four publications reporting results from two RCTs were included. For 10 cancer screening biomarkers, no direct evidence on patient-relevant outcomes was available. Only one trial, which simultaneously assessed cancer antigen 125 (CA125) and vaginal ultrasound for ovarian cancer screening, provided the outcome of interest. Screening compared with usual care did not reduce ovarian cancer mortality. Patient harms included overdiagnosis and false-positive results.

CONCLUSION

Although ovarian cancer screening with CA125 showed no benefit, false-positive tests, overdiagnosis and overtreatment were reported. Physicians and laboratories should provide patients with comprehensive information about the lack of evidence and potential harms caused by biomarker screening tests offered as a self-pay health service.

Less Is More: The Evolving Surgical Approach to Breast Cancer

Personalized medicine is emerging as an important guiding principle in diagnosis and treatment. This means not just doing more for some, but safely doing less for others. The lessons learned about the biology of breast cancer over the last 2 decades have enabled us to understand the incredible heterogeneity of breast cancer and its associated behavior. Although much work remains, there is an emerging opportunity to identify and recognize more indolent forms of breast cancer, made more prevalent through the widespread adoption of screening. With our improving systemic therapies and improved molecular tools, we now have the opportunity to reduce the burden of treatment in women with lower-risk tumors. Our surgical treatments have evolved, with less morbid and more cosmetic procedures. In this article, we review the indications for further reducing local therapy, including adjuvant radiation.

To screen or not to screen for breast cancer? How do modelling studies answer the question?

Breast cancer screening is a topic of hot debate, and currently no general consensus has been reached on starting and ending ages and screening intervals, in part because of a lack of precise estimations of the benefit-harm ratio. Simulation models are often applied to account for the expected benefits and harms of regular screening; however, the degree to which the model outcomes are reliable is not clear. In a recent systematic review, we therefore aimed to assess the quality of published simulation models for breast cancer screening of the general population. The models were scored according to a framework for qualitative assessment. We distinguished seven original models that utilized a common model type, modelling approach, and input parameters. The models predicted the benefit of regular screening in terms of mortality reduction; and overall, their estimates compared well to estimates of mortality reduction from randomized controlled trials. However, the models did not report on the expected harms associated with regular screening. We found that current simulation models for population breast cancer screening are prone to many pitfalls; their outcomes bear a high overall risk of bias, mainly because of a lack of systematic evaluation of evidence to calibrate the input parameters and a lack of external validation. Our recommendations concerning future modelling are therefore to use systematically evaluated data for the calibration of input parameters, to perform external validation of model outcomes, and to account for both the expected benefits and the expected harms so as to provide a clear balance and cost-effectiveness estimation and to adequately inform decision-makers.

Screening and overdiagnosis: public health implications

Overdiagnosis is the diagnosis of an abnormality that bears no substantial health hazard and no benefit for patients to be aware of. Resulting mainly from the use of increasingly sensitive screening and diagnostic tests, as well as broadened definitions of conditions requiring an intervention, overdiagnosis is a growing but still largely misunderstood public health issue. Fear of missing a diagnosis or of litigation, financial incentives or patient's need of reassurance are further causes of overdiagnosis. The main consequence of overdiagnosis is overtreatment. Treating an overdiagnosed condition bears no benefit but can cause harms and generates costs. Overtreatment also diverts health professionals from caring for those most severely ill. Recognition of overdiagnosis due to screening is challenging since it is rarely identifiable at the individual level and difficult to quantify precisely at the population level. Overdiagnosis exists even for screening of proven efficacy and efficiency. Measures to reduce overdiagnosis due to screening include heightened sensitization of health professionals and patients, active surveillance and deferred treatment until early signs of disease progression and prognosis estimation through biomarkers (including molecular) profiling. Targeted screening and balanced information on its risk and benefits would also help limit overdiagnosis. Research is needed to assess the public health burden and implications of overdiagnosis due to screening activity.

For which cancers might patients benefit most from expedited symptomatic diagnosis? Construction of a ranking order by a modified Delphi technique

BACKGROUND

This study aimed to answer the question 'for which cancers, in a symptomatic patient, does expediting the diagnosis provide an improvement in mortality and/or morbidity?'

METHODS

An initial ranking was constructed from previous work identifying 'avoidable deaths' for 21 common cancers in the UK. In a two-round modified Delphi exercise, 22 experts, all experienced across multiple cancers, used an evidence pack summarising recent relevant publications and their own experience to adjust this ranking. Participants also answered on a Likert scale whether they anticipated mortality or morbidity benefits for each cancer from expedited diagnosis.

RESULTS

Substantial changes in ranking occurred in the Delphi exercise. Finally, expedited diagnosis was judged to provide the greatest mortality benefit in breast cancer, uterine cancer and melanoma, and least in brain and pancreatic cancers. Three cancers, prostate, brain and pancreas, attracted a median answer of 'disagree' to whether they expected mortality benefits from expedited diagnosis of symptomatic cancer.

CONCLUSIONS

Our results can guide future research, with emphasis given to studying interventions to improve symptomatic diagnosis of those cancers ranked highly. In contrast, research efforts for cancers with the lowest rankings could be re-directed towards alternative avenues more likely to yield benefit, such as screening or treatment.

Breast Cancer Screening for Women at Average Risk: 2015 Guideline Update From the American Cancer Society

IMPORTANCE

Breast cancer is a leading cause of premature mortality among US women. Early detection has been shown to be associated with reduced breast cancer morbidity and mortality.

OBJECTIVE

To update the American Cancer Society (ACS) 2003 breast cancer screening guideline for women at average risk for breast cancer.

PROCESS

The ACS commissioned a systematic evidence review of the breast cancer screening literature to inform the update and a supplemental analysis of mammography registry data to address questions related to the screening interval. Formulation of recommendations was based on the quality of the evidence and judgment (incorporating values and preferences) about the balance of benefits and harms.

EVIDENCE SYNTHESIS

Screening mammography in women aged 40 to 69 years is associated with a reduction in breast cancer deaths across a range of study designs, and inferential evidence supports breast cancer screening for women 70 years and older who are in good health. Estimates of the cumulative lifetime risk of false-positive examination results are greater if screening begins at younger ages because of the greater number of mammograms, as well as the higher recall rate in younger women. The quality of the evidence for overdiagnosis is not sufficient to estimate a lifetime risk with confidence. Analysis examining the screening interval demonstrates more favorable tumor characteristics when premenopausal women are screened annually vs biennially. Evidence does not support routine clinical breast examination as a screening method for women at average risk.

RECOMMENDATIONS

The ACS recommends that women with an average risk of breast cancer should undergo regular screening mammography starting at age 45 years (strong recommendation). Women aged 45 to 54 years should be screened annually (qualified recommendation). Women 55 years and older should transition to biennial screening or have the opportunity to continue screening annually (qualified recommendation). Women should have the opportunity to begin annual screening between the ages of 40 and 44 years (qualified recommendation). Women should continue screening mammography as long as their overall health is good and they have a life expectancy of 10 years or longer (qualified recommendation). The ACS does not recommend clinical breast examination for breast cancer screening among average-risk women at any age (qualified recommendation).

CONCLUSIONS AND RELEVANCE

These updated ACS guidelines provide evidence-based recommendations for breast cancer screening for women at average risk of breast cancer. These recommendations should be considered by physicians and women in discussions about breast cancer screening.

Image toggling saves time in mammography

When two images are perfectly aligned, even subtle differences are readily detected when the images are "toggled" back and forth in the same location. However, substantial changes between two photographs can be missed if the images are misaligned ("change blindness"). Nevertheless, recent work from our lab, testing nonradiologists, suggests that toggling misaligned photographs leads to superior performance compared to side-by-side viewing (SBS). In order to determine if a benefit of toggling misaligned images may be observed in clinical mammography, we developed an image toggling technique where pairs of new and prior breast imaging exam images could be efficiently toggled back and forth. Twenty-three radiologists read 10 mammograms evenly divided in toggle and SBS modes. The toggle mode led to a 6-s benefit in reaching a decision [[Formula: see text], [Formula: see text]]. The toggle viewing mode also led to a 5% improvement in diagnostic accuracy, though in our small sample this effect was not statistically reliable. Time savings were found even though successive mammograms were not perfectly aligned. Given the ever-increasing caseload for radiologists, this simple manipulation of how the images are viewed could save valuable time in clinical practice, allowing radiologists to read more cases or spend more time on difficult cases.

Evaluation of health benefits and harms of the breast cancer screening programme in the Basque Country using discrete event simulation

BACKGROUND

Since the breast cancer screening programme in the Basque Country (BCSPBC) was started in 1996, more than 400,000 women aged 50 to 69 years have been invited to participate. Based on epidemiological observations and simulation techniques it is possible to extend observed short term data into anticipated long term results. The aim of this study was to assess the effectiveness of the programme through 2011 by quantifying the outcomes in breast cancer mortality, life-years gained, false positive results, and overdiagnosis.

METHODS

A discrete event simulation model was constructed to reproduce the natural history of breast cancer (disease-free, pre-clinical, symptomatic, and disease-specific death) and the actual observed characteristics of the screening programme during the evaluated period in the Basque women population. Goodness-of-fit statistics were applied for model validation. The screening effects were measured as differences in benefits and harms between the screened and unscreened populations. Breast cancer mortality reduction and life-years gained were considered as screening benefits, whereas, overdiagnosis and false positive results were assessed as harms. Results for a single cohort were also obtained.

RESULTS

The screening programme yielded a 16 % reduction in breast cancer mortality and a 10 % increase in the incidence of breast cancer through 2011. Almost 2 % of all the women in the programme had a false positive result during the evaluation period. When a single cohort was analysed, the number of deaths decreased by 13 %, and 4 % of screen-detected cancers were overdiagnosed. Each woman with BC detected by the screening programme gained 2.5 life years due to early detection corrected by lead time.

CONCLUSIONS

Fifteen years after the screening programme started, this study supports an important decrease in breast cancer mortality due to the screening programme, with reasonable risk of overdiagnosis and false positive results, and sustains the continuation of the breast cancer screening programme in the Basque population.