Stage-specific incidence and survival of breast cancer in Norway: The implications of changes in coding and classification practice

Breast and cervical cancer screening practices in nine countries of Eastern Europe and Central Asia: A population-based survey

BACKGROUND

Eastern Europe and Central Asia (EECA) countries have higher cervical and breast cancer mortality rates and later stage at diagnosis compared with the rest of WHO European Region. The aim was to explore current early detection practices including "dispensarization" for breast and cervix cancer in the region.

METHODS

A questionnaire survey on early detection practices for breast and cervix cancer was sent to collaborators in 11 countries, differentiating services in the primary health setting, and population-based programs. Responses were received from Armenia, Belarus, Georgia, Kazakhstan, Kyrgyzstan, the Russian Federation (Arkhangelsk, Samara and Tomsk regions), Tajikistan, Ukraine, and Uzbekistan.

RESULTS

All countries but Georgia, Kyrgyzstan, and the Russian Federation had opportunistic screening by clinical breast exam within "dispensarization" program. Mammography screening programs, commonly starting from age 40, were introduced or piloted in eight of nine countries, organized at national oncology or screening centres in Armenia, Belarus and Georgia, and within primary care in others. Six countries had "dispensarization" program for cervix cancer, mostly starting from the age 18, with smears stained either by Romanowsky-Giemsa alone (Belarus, Tajikistan and Ukraine), or alternating with Papanicolaou (Kazakhstan and the Russian Federation). In parallel, screening programs using Papanicolaou or HPV test were introduced in seven countries and organized within primary care.

CONCLUSION

Our study documents that parallel screening systems for both breast and cervix cancers, as well as departures from evidence-based practices are widespread across the EECA. Within the framework of the WHO Initiatives, existing opportunistic screening should be replaced by population-based programs that include quality assurance and control.

Secondary and Quaternary Delays in the Diagnosis of Breast Cancer: Are the Physicians Responsible too?

Causes of delay in presentation of breast cancer has been categorised into 'Primary Delay' (delay by the patient or her family); 'Secondary Delay' (delay by the doctors in the first contact - family physician or quacks/alternative medicine practitioners); 'Tertiary Delay' (delay in the system in a specialist breast care unit e.g. waiting list, delayed reporting, doctors on leave, strikes); and 'Quaternary Delay' (e.g. patient hopping from one competent breast cancer specialist to another or mid-course attrition to alternative treatments). In India, many patients have blind belief and high attrition towards the quacks and alternative medicine practitioners. Our study was to assess whether these 'Secondary and Quaternary Delays', particularly the attrition towards the alternative non-modern medical practitioners, have any effect on the delayed presentation and advancement of the overall anatomical staging among the breast cancer patients. We performed a retrospective observational study, based on 'Triple Assessment' and pre-structured Questionnaire. All pathologically confirmed female breast cancer patients admitted from 02/2017 to 08/2018 in the department of General Surgery in our Institute were included. Male breast cancer, histopathologically unconfirmed/inconclusive breast lumps, patients with previous breast surgery/radiotherapy/chemotherapy were excluded. Data from 267 patients was analysed. The mean age at presentation of breast cancer was 47.54 years. The average delay between the onset of the first symptom and the histological diagnosis was 13.76 ± SD 13.08 months. About half (50.2%) of our patients visited the non-modern medical practitioners at least once during their disease. The mean delay in diagnosis was significantly higher (p < 0.0001) among them. The average 'Secondary Delay' was significantly higher among those who visited the non-modern medical practitioners (9.7 ± SD 9.38 months). The average delay between the visit to the first doctor and the histological diagnosis was also significantly higher among them (18.35 ± 14 months). Patients with attrition to non-modern medical practitioners also were diagnosed in higher cT stages: cT4a (66.67%, 2 of 3) and cT4b (60%, 33 of 55). Most (56.9%) of stage IIIB patients visited the non-modern medical practitioners before their diagnosis. Patients who visited the non-modern medical practitioners had significantly more delay in the diagnosis of breast cancer. The 'Secondary and Quaternary Delays' form the major portion in the overall delay and lead to advancement of the anatomical staging of the disease. Creating public awareness, proper training and 'continued medical education' for primary care physicians, and the AYUSH practitioners are required. Further population-based studies are advised.

Comparison of female breast cancer between Russia and Germany: A population-based study on time trends and stage at diagnosis

OBJECTIVES

While a mammography-screening program (MSP) is being offered systematically in Germany since 2009, the dispanserizatsiya has been implemented in Russia since 2013. This study examined trends of stage at breast cancer diagnosis in two Russian regions and compared the results with the development in Germany. In addition, we aimed to gain further insights into the early detection of breast cancer in Russia.

METHODS

Incidence data from two cancer registries in Russia and 12 population-based cancer registries in Germany were used to analyse breast cancer incidence rates among women above age 30 over time. Further, we calculated rate ratios to compare the age group-specific incidence rates after the implementation of MSP in Germany (2010-2014) with the period before implementation (2003-2005) separately for each tumour stage and all stages combined.

RESULTS

During the study period from 2003 to 2014, age-standardised rates for breast cancer were 54.6 and 116.7 per 100,000 for Russia and Germany, respectively. The proportion of the T1 stage at diagnosis among Russian women aged 50 + is half than that in Germany. Nevertheless, we observed an increasing trend of early-stage alongside the reduction of advanced-stage incidence rates of breast cancer in Russia.

CONCLUSIONS

The observed trend in Russia may reflect overall positive changes in early detection of breast cancer, with actual proportion of T1 stage still far behind Germany. Advances in breast cancer screening efforts through the dispanserizatsiya may help to further reduce the breast cancer burden.

Compliance with recommended cancer patient pathway timeframes and choice of treatment differed by cancer type and place of residence among cancer patients in Norway in 2015-2016

Background

Cancer patient pathways (CPPs) were implemented in Norway to reduce unnecessary waiting times, regional variations, and to increase the predictability of cancer care for the patients. This study aimed to determine if 70% of cancer patients started treatment within the recommended time frames, and to identify potential delays.

Methods

Patients registered with a colorectal, lung, breast, or prostate cancer diagnosis at the Cancer Registry of Norway in 2015–2016 were linked with the Norwegian Patient Registry and Statistics Norway. Adjusting for sociodemographic variables, multivariable quantile (median) regressions were used to examine the association between place of residence and median time to start of examination, treatment decision, and start of treatment.

Results

The study included 20 668 patients. The proportions of patients who went through the CPP within the recommended time frames were highest among colon (84%) and breast (76%) cancer patients who underwent surgery and lung cancer patients who started systemic anticancer treatment (76%), and lowest for prostate cancer patients who underwent surgery (43%). The time from treatment decision to start of treatment was the main source of delay for all cancers. Travelling outside the resident health trust prolonged waiting time and was associated with a reduced odds of receiving surgery and radiotherapy for lung and rectal cancer patients, respectively.

Conclusions

Achievement of national recommendations of the CCP times differed by cancer type and treatment. Identified bottlenecks in the pathway should be targeted to decrease waiting times. Further, CPP guidelines should be re-examined to determine their ongoing relevance.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09306-9.

Factors associated with emergency-onset diagnosis, time to treatment and type of treatment in colorectal cancer patients in Norway

Background

International differences in survival among colorectal cancer (CRC) patients may partly be explained by differences in emergency presentations (EP), waiting times and access to treatment.

Methods

CRC patients registered in 2015–2016 at the Cancer Registry of Norway were linked with the Norwegian Patient Registry and Statistics Norway. Multivariable logistic regressions analysed the odds of an EP and access to surgery, radiotherapy and systemic anticancer treatment (SACT). Multivariable quantile regression analysed time from diagnosis to treatment.

Results

Of 8216 CRC patients 29.2% had an EP before diagnosis, of which 81.4% were admitted to hospital with a malignancy-related condition. Higher age, more advanced stage, more comorbidities and colon cancer were associated with increased odds of an EP (p < 0.001). One-year mortality was 87% higher among EP patients (HR=1.87, 95%CI:1.75–2.02). Being married or high income was associated with 30% reduced odds of an EP (p < 0.001). Older age was significantly associated with increased waiting time to treatment (p < 0.001). Region of residence was significantly associated with waiting time and access to treatment (p < 0.001). Male (OR = 1.30, 95%CI:1.03,1.64) or married (OR = 1.39, 95%CI:1.09,1.77) colon cancer patients had an increased odds of SACT. High income rectal cancer patients had an increased odds (OR = 1.48, 95%CI:1.03,2.13) of surgery.

Conclusion

Patients who were older, with advanced disease or more comorbidities were more likely to have an emergency-onset diagnosis and less likely to receive treatment. Income was not associated with waiting time or access to treatment among CRC patients, but was associated with the likelihood of surgery among rectal cancer patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08415-1.

Factors associated with emergency-related diagnosis, time to treatment and type of treatment in 5713 lung cancer patients

Background

International and national differences exist in survival among lung cancer patients. Possible explanations include varying proportions of emergency presentations (EPs), unwanted differences in waiting time to treatment and unequal access to treatment.

Methods

Case-mix-adjusted multivariable logistic regressions the odds of EP and access to surgery, radiotherapy and systemic anticancer treatment (SACT). Multivariable quantile regression analyzed time from diagnosis to first treatment.

Results

Of 5713 lung cancer patients diagnosed in Norway in 2015–16, 37.9% (n = 2164) had an EP before diagnosis. Higher age, more advanced stage and more comorbidities were associated with increasing odds of having an EP (P < 0.001) and a lower odds of receiving any treatment (P < 0.001). After adjusting for case-mix, waiting times to curative radiotherapy and SACT were 12.1 days longer [95% confidence interval (CI): 10.2, 14.0] and 5.6 days shorter (95% CI: −7.3, −3.9), respectively, compared with waiting time to surgery. Patients with regional disease experienced a 4.7-day shorter (Coeff: −4.7, 95% CI:−9.4, 0.0) waiting time to curative radiotherapy when compared with patients with localized disease. Patients with a high income had a 22% reduced odds [odds ratio (OR) = 0.78, 95% CI: 0.63, 0.97] of having an EP, and a 63% (OR = 1.63, 95% CI: 1.20, 2.21) and a 40% (OR = 1.40, 95% CI: 1.12, 1.76) increased odds of receiving surgery and SACT, respectively.

Conclusion

Patients who were older, had advanced disease or increased comorbidities were more likely to have an EP and less likely to receive treatment. While income did not affect the waiting time for lung cancer treatment in Norway, it did affect the likelihood of receiving surgery and SACT.

Benefits and harms of breast cancer mammography screening for women at average risk of breast cancer: A systematic review for the European Commission Initiative on Breast Cancer

OBJECTIVES

Mammography screening is generally accepted in women aged 50-69, but the balance between benefits and harms remains controversial in other age groups. This study systematically reviews these effects to inform the European Breast Cancer Guidelines.

METHODS

We searched PubMed, EMBASE and Cochrane Library for randomised clinical trials (RCTs) or systematic reviews of observational studies in the absence of RCTs comparing invitation to mammography screening to no invitation in women at average breast cancer (BC) risk. We extracted data for mortality, BC stage, mastectomy rate, chemotherapy provision, overdiagnosis and false-positive-related adverse effects. We performed a pooled analysis of relative risks, applying an inverse-variance random-effects model for three age groups (<50, 50-69 and 70-74). GRADE (Grading of Recommendations Assessment, Development and Evaluation) was used to assess the certainty of evidence.

RESULTS

We identified 10 RCTs including 616,641 women aged 38-75. Mammography reduced BC mortality in women aged 50-69 (relative risk (RR) 0.77, 95%CI (confidence interval) 0.66-0.90, high certainty) and 70-74 (RR 0.77, 95%CI 0.54-1.09, high certainty), with smaller reductions in under 50s (RR 0.88, 95%CI 0.76-1.02, moderate certainty). Mammography reduced stage IIA+ in women 50-69 (RR 0.80, 95%CI 0.64-1.00, very low certainty) but resulted in an overdiagnosis probability of 23% (95%CI 18-27%) and 17% (95%CI 15-20%) in under 50s and 50-69, respectively (moderate certainty). Mammography was associated with 2.9% increased risk of invasive procedures with benign outcomes (low certainty).

CONCLUSIONS

For women 50-69, high certainty evidence that mammography screening reduces BC mortality risk would support policymakers formulating strong recommendations. In other age groups, where the net balance of effects is less clear, conditional recommendations will be more likely, together with shared decision-making.

Comparison of breast cancer and cervical cancer stage distributions in ten newly independent states of the former Soviet Union: a population-based study

Background

Screening for breast cancer and cervical cancer in the newly independent states of the former Soviet Union is largely opportunistic, and countries in the region have among the highest cervical cancer incidence in the WHO European Region. We aimed to compare the stage-specific distributions and changes over time in breast cancer and cervical cancer incidence in the newly independent states of the former Soviet Union.

Methods

We collected breast cancer and cervical cancer incidence data from official statistics from Armenia, Azerbaijan, Belarus, Georgia, Kazakhstan, Kyrgyzstan, Republic of Moldova, Russian Federation, Ukraine, and Uzbekistan for the years 2008–17 by tumour, node, metastasis (TNM) stage, and by age where population-based cancer registry data were available. We used log-linear regression to quantify the changes over time in age-standardised rates.

Findings

During the period 2013–17, more than 50% of breast cancer cases across the analysed countries, and more than 75% of breast cancer cases in Belarus, Kazakhstan, and Ukraine, were registered at stages I–II. The proportion of stage I breast cancer cases was highest in the screening age group (50–69 years) compared with other ages in Moldova and the Russian registries, but was highest in those aged 15–49 years in Georgia and Ukraine. Breast cancer stage-specific incidence rates increased over time, most prominently for stage I cancers. For cervical cancer, the proportions of cancers diagnosed at a late stage (stages III and IV) were high, particularly in Moldova and Armenia (>50%). The proportion of stage I cervical cancer cases decreased with age in all countries, whereas the proportions of late stage cancers increased with age. Stage-specific incidence rates of cervical cancer generally increased over the period 2008–17.

Interpretation

Our results suggest modest progress in early detection of breast cancer in the newly independent states of the former Soviet Union. The high proportions of early-stage disease in the absence of mammography screening (eg, in Belarus) provide a benchmark for what is achievable with rapid diagnosis. For cervical cancer, there is a need to tackle the high burden and unfavourable stage-specific changes over time in the region. A radical shift in national policies away from opportunistic screening toward organised, population-based, quality-assured human papillomavirus vaccination and screening programmes is urgently needed.

Funding

Union for International Cancer Control, WHO Regional Office for Europe, and Ministry of Health of Ukraine.

In modern times, how important are breast cancer stage, grade and receptor subtype for survival: a population-based cohort study

Background

In breast cancer, immunohistochemistry (IHC) subtypes, together with grade and stage, are well-known independent predictors of breast cancer death. Given the immense changes in breast cancer treatment and survival over time, we used recent population-based data to test the combined influence of IHC subtypes, grade and stage on breast cancer death.

Methods

We identified 24,137 women with invasive breast cancer aged 20 to 74 between 2005 and 2015 in the database of the Cancer Registry of Norway. Kaplan-Meier curves, mortality rates and adjusted hazard ratios for breast cancer death were estimated by IHC subtypes, grade, tumour size and nodal status during 13 years of follow-up.

Results

Within all IHC subtypes, grade, tumour size and nodal status were independent predictors of breast cancer death. When combining all prognostic factors, the risk of death was 20- to 40-fold higher in the worst groups compared to the group with the smallest size, low grade and ER+PR+HER2− status. Among node-negative ER+HER2− tumours, larger size conferred a significantly increased breast cancer mortality. ER+PR−HER2− tumours of high grade and advanced stage showed particularly high breast cancer mortality similar to TNBC. When examining early versus late mortality, grade, size and nodal status explained most of the late (> 5 years) mortality among ER+ subtypes.

Conclusions

There is a wide range of risks of dying from breast cancer, also across small breast tumours of low/intermediate grade, and among node-negative tumours. Thus, even with modern breast cancer treatment, stage, grade and molecular subtype (reflected by IHC subtypes) matter for prognosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13058-021-01393-z.

Socioeconomic inequalities in stage-specific breast cancer incidence: a nationwide registry study of 1.1 million young women in Norway, 2000-2015

BACKGROUND

Women with high socioeconomic status (SES) have the highest incidence rates of breast cancer. We wanted to determine if high SES women only have higher rates of localized disease, or whether they also have higher rates of non-localized disease. To study this, we used data on a young population with universal health care, but not offered screening.

MATERIAL AND METHODS

Using individually linked registry data, we compared stage-specific breast cancer incidence, by education level and income quintile, in a Norwegian cohort of 1,106,863 women aged 30-48 years during 2000-2015 (N = 7531 breast cancer cases). We calculated stage-specific age-standardized rates and incidence rate ratios and rate differences using Poisson models adjusted for age, period and immigration history.

RESULTS

Incidence of localized and regional disease increased significantly with increasing education and income level. Incidence of distant stage disease did not vary significantly by education level but was significantly reduced in the four highest compared to the lowest income quintile. The age-standardized rates for tertiary versus compulsory educated women were: localized 28.2 vs 19.8, regional 50.8 vs 40.4 and distant 2.3 vs 2.6 per 100,000 person-years. The adjusted incidence rate ratios (tertiary versus compulsory) were: localized 1.40 (95% CI 1.25-1.56), regional 1.25 (1.15-1.35), distant 0.90 (0.64-1.26). The age-standardized rates for women in the highest versus lowest income quintile were: localized 28.9 vs 17.7, regional 52.8 vs 41.5 and distant 2.3 vs 3.2 per 100,000 person-years. The adjusted incidence rate ratios (highest versus lowest quintile) were: localized 1.63 (1.42-1.87), regional 1.27 (1.09-1.32), distant 0.64 (0.43-0.94).

CONCLUSION

Increased breast cancer rates among young high SES women is not just increased detection of small localized tumors, but also increased incidence of tumors with regional spread. The higher incidence of young high SES women is therefore real and not only because of excessive screening.

Stage-specific survival has improved for young breast cancer patients since 2000: but not equally

Purpose

The stage-specific survival of young breast cancer patients has improved, likely due to diagnostic and treatment advances. We addressed whether survival improvements have reached all socioeconomic groups in a country with universal health care and national treatment guidelines.

Methods

Using Norwegian registry data, we assessed stage-specific breast cancer survival by education and income level of 7501 patients (2317 localized, 4457 regional, 233 distant and 494 unknown stage) aged 30–48 years at diagnosis during 2000–2015. Using flexible parametric models and national life tables, we compared excess mortality up to 12 years from diagnosis and 5-year relative survival trends, by education and income as measures of socioeconomic status (SES).

Results

Throughout 2000–2015, regional and distant stage 5-year relative survival improved steadily for patients with high education and high income (high SES), but not for patients with low education and low income (low SES). Regional stage 5-year relative survival improved from 85 to 94% for high SES patients (9% change; 95% confidence interval: 6, 13%), but remained at 84% for low SES patients (0% change; − 12, 12%). Distant stage 5-year relative survival improved from 22 to 58% for high SES patients (36% change; 24, 49%), but remained at 11% for low SES patients (0% change; − 19, 19%).

Conclusions

Regional and distant stage breast cancer survival has improved markedly for high SES patients, but there has been little survival gain for low SES patients. Socioeconomic status matters for the stage-specific survival of young breast cancer patients, even with universal health care.

Electronic supplementary material

The online version of this article (10.1007/s10549-020-05698-z) contains supplementary material, which is available to authorized users.

Patient and tumour characteristics associated with inclusion in Cancer patient pathways in Norway in 2015-2016

BACKGROUND

Cancer patient pathways (CPPs) were implemented in 2015 to reduce waiting time, regional variation in waiting time, and to increase the predictability of cancer care for the patients. The aims of this study were to see if the national target of 70% of all cancer patients being included in a CPP was met, and to identify factors associated with CPP inclusion.

METHODS

All patients registered with a colorectal, lung, breast or prostate cancer diagnosis at the Cancer Registry of Norway in the period 2015-2016 were linked with the Norwegian Patient Registry for CPP information and with Statistics Norway for sociodemographic variables. Multivariable logistic regression examined if the odds of not being included in a CPP were associated with year of diagnosis, age, sex, tumour stage, marital status, education, income, region of residence and comorbidity.

RESULTS

From 2015 to 2016, 30,747 patients were diagnosed with colorectal, lung, breast or prostate cancer, of whom 24,429 (79.5%) were included in a CPP. Significant increases in the probability of being included in a CPP were observed for colorectal (79.1 to 86.2%), lung (79.0 to 87.3%), breast (91.5 to 97.2%) and prostate cancer (62.2 to 76.2%) patients (p < 0.001). Increasing age was associated with an increased odds of not being included in a CPP for lung (p < 0.001) and prostate cancer (p < 0.001) patients. Colorectal cancer patients < 50 years of age had a two-fold increase (OR = 2.23, 95% CI: 1.70-2.91) in the odds of not being included in a CPP. The odds of no CPP inclusion were significantly increased for low income colorectal (OR = 1.24, 95%CI: 1.00-1.54) and lung (OR = 1.52, 95%CI: 1.16-1.99) cancer patients. Region of residence was significantly associated with CPP inclusion (p < 0.001) and the probability, adjusted for case-mix ranged from 62.4% in region West among prostate cancer patients to 97.6% in region North among breast cancer patients.

CONCLUSIONS

The national target of 70% was met within 1 year of CPP implementation in Norway. Although all patients should have equal access to CPPs, a prostate cancer diagnosis, older age, high level of comorbidity or low income were significantly associated with an increased odds of not being included in a CPP.

Terminal digit preference: a source of measurement error in breast cancer diameter reporting

Objectives: Women diagnosed with breast cancer are offered treatment and therapy based on tumor characteristics, including tumor diameter. There is scarce knowledge whether tumor diameter is accurately reported, or whether it is unconsciously rounded to the nearest half-centimeter (terminal digit preference). This study aimed to assess the precision (number of digits) of breast cancer tumor diameters and whether they are affected by terminal digit preference. Furthermore, we aimed to assess the agreement between mammographic and histopathologic tumor diameter measurements.Material and Methods: This national registry study included reported mammographic and registered histopathologic tumor diameter information from the Cancer Registry of Norway for invasive breast cancers diagnosed during 2012-2016. Terminal digit preference was assessed using histograms. Agreement between mammographic and histopathologic measurements was assessed using the intraclass correlation coefficient (ICC) and Bland-Altman plots.Results: Mammographic, histopathologic, or both tumor measurements were available for 7792, 13,541 and 6865 cases, respectively. All mammographic and 97.2% of histopathologic tumor diameters were recorded using whole mm. Terminal digits of zero or five were observed among 38.7% and 34.8% of mammographic and histopathologic measurements, respectively. There was moderate agreement between the two measurement methods (ICC = 0.52, 95% CI: 0.50-0.53). On average, mammographic measurements were 1.26 mm larger (95% limits of agreement: -22.29-24.73) than histopathologic measurements. This difference increased with increasing tumor size.Conclusion: Terminal digit preference was evident among breast cancer tumor diameters in this nationwide study. Further studies are needed to investigate the potential extent of under-staging and under-treatment resulting from this measurement error.

Validation study of MARCKSL1 as a prognostic factor in lymph node-negative breast cancer patients

Protein expression of Myristoylated alanine-rich C kinase substrate like-1 (MARCKSL1) has been identified as a prognostic factor in lymph-node negative (LN^-) breast cancer patients. We aim to validate MARCKSL1 protein expression as a prognostic marker for distant metastasis-free survival (DMFS) in a new cohort of LN^- breast cancer patients. MARCKSL1 expression was evaluated in 151 operable T_1,2N₀M₀ LN^- breast cancer patients by immunohistochemistry. Median follow-up time was 152 months, range 11–189 months. Results were compared with classical prognosticators (age, tumor diameter, grade, estrogen receptor, and proliferation) using single (Kaplan-Meier) and multivariate (Cox model) survival analysis. Thirteen patients (9%) developed distant metastases. With both single and multiple analysis of all features, MARCKSL1 did not show a significant prognostic value for DMFS (p = 0.498). Of the assessed classical prognosticators, only tumor diameter showed prognostic value (hazard ratio 9.3, 95% confidence interval 2.8–31.0, p <0.001). MARCKSL1 expression could not be confirmed as a prognostic factor in this cohort. Possible reasons include changes in diagnostic and treatment guidelines between the discovery and validation cohorts. Further studies are needed to reveal the potential biological role of this protein in breast cancer.

The impact of mammography screening programmes on incidence of advanced breast cancer in Europe: a literature review

Background

Observational studies have reported conflicting results on the impact of mammography service screening programmes on the advanced breast cancer rate (ABCR), a correlation that was firmly established in randomized controlled trials. We reviewed and summarized studies of the effect of service screening programmes in the European Union on ABCR and discussed their limitations.

Methods

The PubMed database was searched for English language studies published between 01-01-2000 and 01–06-2018. After inspection of titles and abstracts, 220 of the 8644 potentially eligible papers were considered relevant. Their abstracts were reviewed by groups of two authors using predefined criteria. Fifty studies were selected for full paper review, and 22 of these were eligible. A theoretical framework for their review was developed. Review was performed using a ten-point checklist of the methodological caveats in the analysis of studies of ABCR and a standardised assessment form designed to extract quantitative and qualitative information.

Results

Most of the evaluable studies support a reduction in ABCR following the introduction of screening. However, all studies were challenged by issues of design and analysis which could at least potentially cause bias, and showed considerable variation in the estimated effect. Problems were observed in duration of follow-up time, availability of reliable reference ABCR, definition of advanced stage, temporal variation in the proportion of unknown-stage cancers, and statistical approach.

Conclusions

We conclude that much of the current controversy on the impact of service screening programmes on ABCR is due to observational data that were gathered and/or analysed with methodological approaches which could not capture stage effects in full. Future research on this important early indicator of screening effectiveness should focus on establishing consensus in the correct methodology.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4666-1) contains supplementary material, which is available to authorized users.