Divergent effects of switching from cytology to HPV-based screening in the Nordic countries.

BACKGROUND: Cervical cytology has been the primary method of cervical cancer screening for decades. Tests that detect viral HPV are shown in several randomized trials to provide better protection against cancer compared with cytology. HPV-based screening has been implemented alongside cytology in the Nordic countries for several years. The aim of this study was to compare cytology and HPV-based screening in the colposcopy referrals and detection rates of cervical lesions. METHODS: Individual-level screening data from Finland, Iceland, Norway and Sweden were harmonized and aggregated locally. We utilized data for tests taken during years 2015-17 and biopsies taken during years 2015-19 to allow 24 months of follow-up. Age-standardized estimates and age-adjusted risk ratios for six different outcomes of screening management were calculated. RESULTS: The age-standardized colposcopy rates were higher in HPV-based testing compared with cytology in Finland (3.5% vs. 0.9%) and Norway (6.0% vs. 4.1%) but lower in Sweden (3.7% vs. 4.9%). The relative detection rate of cervical intraepithelial neoplasia grade 2 and above in HPV-based testing compared with cytology was highest in Finland (RR 2.37, 95% CI 2.13-2.63) and Norway (RR 1.66, 95% CI 1.57-1.72) while in Sweden the difference was not statistically significant (RR 0.98, 95% CI 0.95-1.00). CONCLUSIONS: The effects of implementing HPV screening varied by country as different screening algorithms were implemented. HPV-based screening increases colposcopy rates mainly through referrals from increased repeat testing and detection rate is therefore significantly higher compared with cytology. Monitoring of these indicators in subsequent rounds of HPV-based screening remains essential.

Cervical cancer mortality in Norway according to screening attendance and age.

INTRODUCTION: The association between cervical cancer screening and reduction of cervical cancer has been dealt with in much research. However, little has been published on the association between screening and cervical cancer mortality. We assessed cervical cancer deaths according to screening history, histopathology, and age among women in, under, and above screening age. MATERIAL AND METHODS: In this nationwide, registry-based case-control study from Norway, we included 817 cervical cancer deaths in women diagnosed with cervical cancer in the period 1998-2009. We matched each case with 10 population-based controls free from cervical cancer, obtained by density-based sampling. Odds ratios (ORs) with 95% confidence intervals (CIs) for the association between screening attendance and cervical cancer mortality were estimated using conditional logistic regression models. RESULTS: Of all fatal cervical cancers, 35% were diagnosed among women over screening age and altogether, 83% were either in age groups not covered by the screening program or in non-attenders of screening age. The estimated risk reduction associated with a cytology test in the preceding 3.5 years was 80% in screening age 25-69 years (OR 0.20; 95% CI 0.16-0.24) with the largest reduction in squamous cell carcinomas (84%) but also a substantial estimated risk reduction of 65% for adenocarcinomas. The associated risk reduction was strongest in women aged 45-69 years, with ORs in the range 0.09-0.18, compared with ORs 0.42-1.35 in women aged 25-39 years. CONCLUSIONS: To reduce the mortality of cervical cancer, screening programs should focus on increasing adherence to the program, as half of all the fatal cases were in the non-attender group. Further assessments regarding the potential preventive impact of extending screening to women over the current screening age should be considered.

Setting the record straight-Correcting uterine cancer incidence and mortality in the Nordic countries by reallocation of unspecified cases.

INTRODUCTION: The incidence of and mortality from cancers of the cervix uteri and corpus uteri are underestimated if the presence of uterine cancers, where the exact topography (site of origin) is not specified, is omitted. In this paper we present the corrected figures on mortality from and incidence of cervix and corpus uteri cancers in the Nordic countries by reallocating unspecified uterine cancer deaths and cases to originate either from the corpus uteri or cervix uteri. To further validate the accuracy of reallocation, we also analyzed how well the reallocation captures the changes occurring as the result of a transition in cause of death coding in Norway that took place in 2005. MATERIAL AND METHODS: This study uses data available in the NORDCAN database, which contains aggregated cancer data from all the Nordic countries for the years 1960-2016. The unspecified uterine cancer cases and deaths were reallocated to either cervix uteri or corpus uteri based on the estimated probability that follows the distribution of cases and deaths with verified topography. The estimated proportions of cases and deaths for both cancers were calculated for each combination of age group, year, and country as a proportion of cases (and deaths, respectively) with known topography. Annual age-standardized rates were calculated by direct age-adjustment. RESULTS: The proportions of unspecified uterine cancers were higher in the mortality data than in incidence data, with mean values for 1960-2016 ranging between 5.1% and 26.6% and between 0.2% and 6.8% by country, respectively. In the Nordic countries combined, the reallocation increased the number of cases by 4% and deaths by approximately 20% for both cancers. Finland was the only Nordic country where the mortality rate did not increase substantially after reallocation. CONCLUSIONS: The reallocation procedure had a significant impact on mortality from cancers of the cervix and corpus uteri for countries where the proportion of cancer deaths coded as uterus, not otherwise specified, is substantial. More effort to validate cause of death data with incidence data from cancer registries is warranted to avoid erroneous conclusions of temporal trends based on uncorrected cancer burden.

Cervical cancer in women under 30 years of age in Norway: a population-based cohort study.

BACKGROUND: We compared women with incident cervical cancer under the age of 30 with older women with regard to stage, morphology, screening history and cervical cancer mortality in a population-based cohort study. METHODS: We included data from the Cancer Registry of Norway. Incidence rates (per 100,000 women-years) were calculated and joinpoint regression was used to analyse trends. The Nelson-Aalen cumulative hazard function for risk of cervical cancer death during a 15-year follow-up was displayed. The hazard ratios (HRs) of cervical cancer mortality with 95% confidence intervals (CIs) were derived from Cox regression models. RESULTS: The incidence of cervical cancer in women under the age of 30 has almost tripled since the 1950s, with the steepest increase during 1955-80 (with an annual percentage change (APC) of 7.1% (95%CI 4.4-9.8)) and also an increase after 2004 (3.8% (95%CI -1.3-9.2)). Out of 21,160 women with cervical cancer (1953-2013), 5.3% were younger than 30 years. A lower proportion of younger women were diagnosed at more advanced stages and a slightly higher proportion were diagnosed with adenocarcinoma and adenosquamous carcinoma comparing women above 30 years. The cumulative risk of cervical cancer death was lower for patients under the age of 30. However, the difference between the age groups decreased over time. The overall adjusted HR of cervical cancer mortality was 0.69 (95% CI 0.58-0.82) in women diagnosed under the age of 30 compared to older women. CONCLUSION: There has been an increase in cervical cancer incidence in women under the age of 30. Cervical cancer in younger women was not more advanced at diagnosis compared to older women, and the cervical cancer mortality was lower.

Comparison of cytology and human papillomavirus-based primary testing in cervical screening programs in the Nordic countries.

OBJECTIVE: To compare primary test positivity in cytology and human papillomavirus-based screening between different Nordic cervical cancer screening programs using harmonized register data. METHODS: This study utilized individual-level data available in national databases in Finland, Iceland, Norway, and Sweden. Cervical test data from each country were converted to standard format and aggregated by calculating the number of test episodes for every test result for each calendar year and one-year age group and test method. Test positivity was estimated as the proportion of positive test results of all primary test episodes with a valid test result for "any positive" and "clearly positive" results. RESULTS: The age-adjusted rate ratio for any positive test results in primary human papillomavirus-based screening compared to cytology was 1.66 (95% CI 1.64-1.68). The age-adjusted rate ratio for clearly positive test results was 1.02 (95% CI 1.00-1.05). A decreasing rate ratio by age was seen in both any positive and clearly positive test results. Test positivity increased over time in Iceland, Norway, and Sweden but slightly decreased in Finland. CONCLUSIONS: The probability of any positive test result was higher in human papillomavirus testing than in primary cytology, even though the cross-sectional detection of a clearly positive test result was the same. Human papillomavirus testing can still lead to an improved longitudinal sensitivity through a larger number of follow-up tests and the opportunity to identify women with a persistent human papillomavirus infection. Further research on histologically verified precancerous lesions is needed in primary as well as repeat testing.

Adherence to international recommendations in the governance and organisation of Nordic cervical cancer screening programmes.

INTRODUCTION: Screening has been the primary reason for the decline in the incidence and mortality of cervical cancer in the Nordic countries since the beginning of screening in the 1960s. Recently, the incidence of cervical cancer has increased in the Nordic countries indicating the need to look closely at possibilities for further improvement in screening. This article provides an overview of cervical cancer screening programmes in the Nordic countries and whether the programmes adhere to international recommendations. MATERIALS AND METHODS: Relevant and unambiguous screening recommendations were extracted from applicable literature and classified into legal framework, governance, organisation, and monitoring and evaluation. The up-to-date status of screening programmes and adherence to selected recommendations was gathered from official documentation and co-authors representing cervical cancer screening programmes in all the Nordic countries. RESULTS: A total of 168 recommendations were extracted and 54 of them were considered to be unambiguous and relevant. Forty-nine recommendations were included after synthesising similar recommendations. All Nordic countries adhere to recommendations related to legal framework, but adherence was lower with recommendations related to governance and organisation of screening. Monitoring and evaluation are also areas where adherence to recommendations could be improved. CONCLUSIONS: The Nordic cervical cancer screening programmes have substantially decreased cancer burden despite not fully adhering to many of the recommendations. The presented gaps in adherence suggest that there is room for improvement in the screening programmes. Establishing clearer governance structures would still increase the ability to manage changes such as implementing HPV testing as the primary screening method or modifying the programme when HPV vaccinated cohorts of women enter the target age for screening.

Performance indicators in breast cancer screening in the European Union: A comparison across countries of screen positivity and detection rates.

Comparable performance indicators for breast cancer screening in the European Union (EU) have not been previously reported. We estimated adjusted breast cancer screening positivity rate (PR) and detection rates (DR) to investigate variation across EU countries. For the age 50-69 years, the adjusted EU-pooled PR for initial screening was 8.9% (cross-programme variation range 3.2-19.5%) while DR of invasive cancers was 5.3/1,000 (range 3.8-7.4/1,000) and DR of ductal carcinoma in situ (DCIS) was 1.3/1,000 (range 0.7-2.7/1,000). For subsequent screening, the adjusted EU-pooled PR was 3.6% (range 1.4-8.4%), the DR was 4.0/1,000 (range 2.2-5.8/1,000) and 0.8/1,000 (range 0.5-1.3/1,000) for invasive and DCIS, respectively. Adjusted performance indicators showed remarkable heterogeneity, likely due to different background breast cancer risk and awareness between target populations, and also different screening protocols and organisation. Periodic reporting of the screening indicators permits comparison and evaluation of the screening activities between and within countries aiming to improve the quality and the outcomes of screening programmes. Cancer Screening Registries would be a milestone in this direction and EU Screening Reports provide a fundamental contribution to building them.

Key issues that need to be considered while revising the current annex of the European Council Recommendation (2003) on cancer screening.

The 2003 European Council recommendation urging the Member States to introduce or scale up breast, cervical and colorectal cancer screening through an organized population-based approach has had a remarkable impact. We argue that the recommendation needs to be updated for at least two sets of reasons. First, some of the current clinical guidelines include new tests or protocols that were not available at the time of the Council document. Some have already been adopted by organized screening programs, such as newly defined age ranges for mammography screening, Human Papillomavirus (HPV)-based cervical cancer screening, fecal immunochemical test (FIT) and sigmoidoscopy for colorectal cancer screening. Second, the outcomes of randomized trials evaluating screening for lung and prostate cancer have been published recently and the balance between harms and benefits needs to be pragmatically assessed. In the European Union, research collaboration and networking to exchange and develop best practices should be regularly supported by the European Commission. Integration between primary and secondary preventive strategies through comprehensive approaches is necessary not only to maximize the reduction in cancer burden but also to control the rising trend of other noncommunicable diseases sharing the same risk factors.

Atypical glandular lesions of the cervix and risk of cervical cancer.

INTRODUCTION: Cytology screening has been effective in reducing risks for cervical squamous cell carcinoma but less so for adenocarcinoma. We explored the association of atypical glandular cells or absence of glandular cells in cytology, and subsequent histological diagnoses and cancer risk. MATERIAL AND METHODS: All women in Norway with atypical glandular cells of undetermined significance (AGUS), adenocarcinoma in situ (ACIS) and normal/benign cells, but absence of endocervical or metaplastic cells (NC-NEC) in their first cytology during 1992-2014 (NC-NEC; 2005-2014), recorded in the Cancer Registry of Norway, were included (n = 142 445). Histology diagnoses (stratified by age) within 1 and 3 years after cytology were examined. The Nelson-Aalen cumulative hazard function for gynecological cancer risk was displayed. RESULTS: The majority of AGUS and particularly ACIS were followed with histology within 1 and 3 years. Cervical intraepithelial neoplasia (CIN) lesions were more common in women <35 than in women ≥35 years. Cervical adenocarcinoma followed 13% of ACIS after 1 and 3 years. After ACIS and AGUS, cervical adenocarcinoma was the most frequent cancer subtype. Cumulative risks of cervical adenocarcinoma following ACIS, AGUS and NC-NEC were 3.5%, 0.9% and 0.05%, respectively, after 22, 22 and 9 years of follow-up. CONCLUSIONS: There was a high-risk of glandular malignancies after AGUS and ACIS in cytology. If effective treatment of pre-cancer and early cancer is available, cytology screening provides some level of prevention of adenocarcinoma. Lack of glandular cells did not entail a higher cancer risk.

NordScreen - an interactive tool for presenting cervical cancer screening indicators in the Nordic countries.

Introduction: Quality assurance and improvement of cancer screening programs require up-to-date monitoring systems and evidence-based indicators. National quality reports exist but the definition and calculation of indicators vary making comparisons between countries difficult. The aim is to stimulate collaborative research and quality improvements in screening through freely available, comparable and regularly updated quality indicators. The project currently includes data on cervical cancer screening but population-based screening programs for breast cancer and colorectal cancer may be included in the future. Material and methods: Through a network of Nordic and Baltic screening managers, population-based individual screening data from each country were converted to standard format in each collaborative center, aggregated by the same R program script and then uploaded to the NordScreen online platform. Registry data included all cervical tests except for Finland where only tests based on invitation are included. Results: The NordScreen collaboration has so far collated standardized indicators based on 32.8 million screening tests from four Nordic countries and Estonia. Interactive comparison of test coverage and distribution of women by number of tests are currently possible online. In 2016, the test coverage within a time interval of 5.5 years in the age group 30-64 year-olds was between 78 and 84% in Iceland, Norway and Sweden whereas 70% in Finland. The application allows users to choose indicator specifications interactively. Conclusions: NordScreen is a pilot model for comparable, reliable and accessible cross-country comparisons of cancer screening. Comparability between countries is enhanced by a uniform data structure and standardized calculations. The comparison of coverage rates to national figures shows that the methods used nationally and in the NordScreen project produce similar results.

Invitation strategies and coverage in the population-based cancer screening programmes in the European Union.

The aim of this study was to describe the compliance of the population-based cancer screening programmes in the European Union Member States to the invitation strategies enumerated in the European Guidelines and the impact of such strategies on the invitational coverage. Experts in screening programme monitoring from the respective countries provided data. Coverage by invitation was calculated as the proportion of individuals in the target age range receiving a screening invitation over the total number of annualized eligible population. The invitation strategies of 30 breasts, 25 cervical and 27 colorectal national or regional population-based screening programmes are described. Individual mail invitations are sent by 28 breasts, 20 cervical and 25 colorectal screening programmes. Faecal occult blood test kits are sent by post in 17 of the colorectal cancer screening programmes. The majority of programmes claimed to have a population registry, although some use health insurance data as the database for sending invitations. At least 95% invitation coverage was reached by 16 breast, six cervical and five colorectal screening programmes. Majority of the programmes comply with the invitation strategies enumerated in the European guidelines, although there is still scope for improvements. Coverage by invitation is below the desirable level in many population-based cancer screening programmes in European Union.

The legal framework for European cervical cancer screening programmes.

BACKGROUND: A comprehensive legal framework needs to be developed to run the health services and to regulate the information systems required to manage and to ensure the quality of cancer screening programmes. The aim of our study was to document and to compare the status of legal basis for cervical screening registration in European countries. METHODS: An electronic questionnaire including questions on governance, decision-making structures and legal framework was developed. The primary responses were collected by September 2016. RESULTS: We sent the questionnaire to representatives of 35 European countries (28 countries of the EU, with the United Kingdom included as 4 countries; 4 EFTA member countries: Iceland, Liechtenstein, Norway, and Switzerland); responses were collected from 33 countries. The legal framework makes it possible to personally invite individuals in 29 countries (88%). Systematic screening registration in an electronic registry is legally enshrined in 23 countries (70%). Individual linkage of records between screening and cancer registries is allowed in 19 of those countries. Linkage studies involving cancer and screening registries have been conducted in 15 countries. CONCLUSION: Although the majority of EU/EFTA countries have implemented population-based screening, only half of them have successfully performed record linkage studies, which are nevertheless a key recommendation for quality assurance of the entire screening process. The European legislation is open to the possibility of using health data for these purposes; however, member states themselves must recognize the public interest to create a legal basis, which would enable all the necessary functions for high-quality cancer screening programmes.

Performance of colorectal cancer screening in the European Union Member States: data from the second European screening report.

OBJECTIVE: To present comparative data about the performance of colorectal cancer (CRC) screening programmes in the European Union Member States (EU MSs). DESIGN: Cross-sectional study. We analysed key performance indicators-participation rate, positivity rate (PR), detection rate (DR) and positive predictive value for adenomas and CRC-based on the aggregated quantitative data collected for the second EU screening report. We derived crude and pooled (through a random effects model) estimates to describe and compare trends across different MSs/regions and screening protocols. RESULTS: Participation rate was higher in countries adopting faecal immunochemical test (FIT) (range: 22.8%-71.3%) than in those using guaiac faecal occult blood test (gFOBT) (range 4.5%-66.6%), and it showed a positive correlation (ρ=0.842, p<0.001) with participation in breast cancer screening in the same areas. Screening performance showed a large variability. Compliance with referral for colonoscopy (total colonoscopy (TC)) assessment ranged between 64% and 92%; TC completion rate ranged between 92% and 99%. PR and DR of advanced adenomas and CRC were higher in FIT, as compared with gFOBT programmes, and independent of the protocol among men, older subjects and those performing their first screening. CONCLUSIONS: The variability in the results of quality indicators across population-based screening programmes highlights the importance of continuous monitoring, as well as the need to promote quality improvement efforts, as recommended in the EU guidelines. The implementation of monitoring systems, ensuring availability of data for the entire process, together with initiatives aimed to enhance reproducibility of histology and quality of endoscopy, represent a priority in screening programmes management.

Status of implementation and organization of cancer screening in The European Union Member States-Summary results from the second European screening report.

The second report on the implementation status of cancer screening in European Union (EU) was published in 2017. The report described the implementation status, protocols and organization (updated till 2016) and invitation coverage (for index year 2013) of breast, cervical and colorectal cancer screening in the EU. Experts in screening programme monitoring (N = 80) from the EU Member States having access to requisite information in their respective countries provided data on breast, cervical and colorectal cancer screening through online questionnaires. Data was collected for screening performed in the framework of publicly mandated programmes only. Filled in questionnaires were received from 26 Member States for all three sites and from one Member State for breast cancer only. Substantial improvement in screening implementation using population-based approach was documented. Among the age-eligible women, 94.7% were residents of Member States implementing or planning population-based breast cancer screening in 2016, compared to 91.6% in 2007. The corresponding figures for cervical cancer screening were 72.3 and 51.3% in 2016 and 2007, respectively. Most significant improvement was documented for colorectal cancer screening with roll-out ongoing or completed in 17 Member States in 2016, compared to only five in 2007. So the access to population-based screening increased to 72.4% of the age-eligible populations in 2016 as opposed to only 42.6% in 2007. The invitation coverage was highly variable, ranging from 0.2-111% for breast cancer, 7.6-105% for cervical cancer and 1.8-127% for colorectal cancer in the target populations. In spite of the considerable progress, much work remains to be done to achieve optimal effectiveness. Continued monitoring, regular feedbacks and periodic reporting are needed to ensure the desired impacts of the programmes.

Advancing the evaluation of cervical cancer screening: development and application of a longitudinal adherence metric.

Background: Attendance to routine cancer screening at repeated intervals is essential for reducing morbidity and mortality of targeted cancers, yet currently defined quality-assurance metrics evaluate coverage within a defined period of time (e.g. 3.5 years). Methods: We developed a longitudinal adherence metric that captures attendance to cancer screening at repeated intervals, and applied the metric to population-based data from the Cancer Registry of Norway that captures two decades of organised cervical cancer screening, including all screening tests and cervical cancer diagnoses for women living in Norway at any time during years 1992-2013 and eligible for at least two screening rounds (1 round = 3.5 years, N = 1 391 812). For each woman, we calculated the proportion of eligible screening rounds with at least one registered cytology test, and categorised women into one of five longitudinal adherence categories: never-screeners, severe under-screeners, moderate under-screeners, guidelines-based screeners and over-screeners. For each category, we evaluated cancer outcomes such as cancer stage at diagnosis. Results: Only 46% of screen-eligible women were consistently screened at least once every 3.5 years, and the majority of these were over-screened. In contrast, 29% were moderately under-screened, 17% were severely under-screened and 8% had never attended screening. Screening behaviour was associated with cancer outcomes; e.g., the proportion of cancers diagnosed at Stage I increased from 21% among never-screeners to 70% among over-screeners. Conclusion: The longitudinal adherence metric evaluates screening performance as a succession of screening episodes, reflecting both guidelines and the fundamental principles of screening, and may be a valuable addition to existing performance indicators.

Cervical cancer incidence in elderly women-biology or screening history?

AIM: In many countries, the age-specific pattern of cervical cancer incidence is currently bipolar with peaks at for instance 45 and 65 years of age. Consequently, a large proportion of cervical cancer cases are presently diagnosed in women above the screening age. The purpose of the study was to determine whether this bipolar pattern in age-specific incidence of cervical cancer reflects underlying biology or can be explained by the fact that the data come from birth cohorts with different screening histories. METHODS: Combination of historical data on cervical screening and population-based cancer incidence data from Denmark 1943-2013, Finland and Norway 1953-2013, and Sweden 1958-2013. RESULTS: Since the implementation of screening, the incidence of cervical cancer has decreased for each successive birth cohort. All birth cohorts showed a unipolar age-specific pattern. In unscreened women in Denmark and Sweden, the incidence peaked around the age of 50; the peak was less marked in Finland; while peak age for unscreened women could not be determined for Norway due to widespread opportunistic screening. The current old-age peak in the incidence of cervical cancer represents residuals from unscreened or underscreened birth cohorts. CONCLUSION: The current bipolar pattern in age-specific incidence of cervical cancer can largely be explained by the different screening histories of successive birth cohorts. While it is reasonable to offer screening to elderly women today, birth cohort trends in disease burden should be carefully monitored to justify permanent changes in upper screening age.