Improving cancer incidence evaluation through local government area matching: a study of the Edo-Benin cancer registry in Nigeria

BACKGROUND

Cancer registries in Nigeria, as well as in other sub-Saharan African countries, face challenges in adhering to international cancer registration standards. We aimed to improve cancer incidence estimation by identifying under-reporting of new cancers through matching patient-reported local government areas (LGAs) in Edo state, Nigeria, to their respective catchment populations.

METHODS

Information on cancers was obtained from records of hospitals, medical clinics, pathology laboratories, and death certificates according to IARC guidelines. We utilized normalized scores to establish consistency in the number of cancers by calendar time, and standardized incidence ratios (SIR) to assess the variation in cancer incidence across LGAs compared to Edo state average. Subsequently, we estimated sex- and site-specific annual incidence using the average number of cancers from 2016 to 2018 and the predicted mid-year population in three LGAs. Age-standardization was performed using the direct method with the World Standard Population of 1966.

RESULTS

The number of incident cancers consistent between 2016-2018 in Egor, Oredo, and Uhunmwonde showed a significantly increased SIR. From 2016 to 2018 in these three LGAs, 1,045 new cancers were reported, with 453 (42.4%) in males and 592 (57.6%) in females. The average annual age-standardized incidence rate (ASR) was 50.6 (95% CI: 45.2 - 56.6) per 105. In men, the highest incidence was prostate cancer (ASR: 22.4 per 105), and in women, it was breast cancer (ASR: 16.5 per 105), and cervical cancer (ASR: 12.0 per 105). Microscopically verified cancers accounted for 98.1%.

CONCLUSIONS

We found lower age-standardized incidence rates than those reported earlier for the Edo state population. Collecting information on the local government areas of the cancers allows better matching with the respective target population. We recommend using LGA information to improve the evaluation of population-based cancer incidence in sub-Saharan countries.

Pairwise association of key lifestyle factors and risk of solid cancers - A prospective pooled multi-cohort register study

Smoking, alcohol consumption, obesity, and physical inactivity are key lifestyle risk factors for cancer. Previously these have been mostly examined singly or combined as an index, assuming independent and equivalent effects to cancer risk. The aim of our study was to systematically examine the joint pairwise and interactive effects of these lifestyle factors on the risk of a first solid primary cancer in a multi-cohort prospective setting. We used pooled data from seven Finnish health survey studies during 1972-2015, with 197,551 participants diagnosed with 16,373 solid malignant primary tumors during follow-up. Incidence of any cancer was analyzed separately without and with lung cancers using Poisson regression with main and interaction effects of key lifestyle factors. When excluding lung cancer, the highest risk of any cancer in men was observed for smokers with a BMI of ≥25 kg/m2 (HR 1.36, 95 % CI 1.25-1.48) and in women for smokers consuming alcohol (HR 1.22, 1.14-1.30). No statistically significant interactions between any studied risk factor pairs were observed. When including lung cancer, the highest HRs among men were observed for smokers who consume alcohol (HR 1.72, 1.57-1.89) and among women for smokers who were physically inactive (HR 1.38, 1.27-1.49). Smoking combined with other lifestyle factors at any exposure level resulted in highest pairwise risks, both in men and women. These results highlight the importance of smoking prevention, but also the importance of preventing obesity and reducing alcohol consumption.

Every tenth malignant solid tumor attributed to overweight and alcohol consumption: A population-based cohort study

BACKGROUND

Recent studies have shown that some four in ten cancers are attributable to a few key risk factors. The aim of this study was to estimate cohort-based population attributable fractions (PAFs) in Finland for potentially modifiable cancer risk factors.

METHODS

Data from eight health studies including 253,953 subjects with 29,802 incident malignant solid tumors were analysed using Bayesian multivariate regression model with multiplicative risk factor effects. We estimated the effects of smoking, excess body weight, alcohol consumption, physical activity, parity and education on cancer incidence and related PAFs by cancer site, accounting for competing mortality.

RESULTS

PAF for all cancer sites and exposures combined was 34% (95% credible interval 29%-39%) in men and 24% (19%-28%) in women. In men, 23% (21%-27%) and in women 8% (6%-9%) of all cancers were attributed to smoking. PAF related to excess body weight was 4% (2%-6%) in men and 5% (2%-7%) in women, to alcohol 7% (3%-10%) in men and 4% (0%-7%) in women, and to excess body weight and alcohol combined 10% (6%-15%) in men and 9% (4%-13%) in women.

CONCLUSION

Smoking was the most important factor contributing to cancer burden in Finnish men and women over the last 40 years. The contribution of excess body weight and alcohol consumption together outweighed the role of smoking in women. As the prevalence of overweight is expected to increase, more efficient public health measures supporting adherence to healthy weight are essential to reduce cancer burden.

Partial substitution of red meat or processed meat with plant-based foods and the risk of colorectal cancer

OBJECTIVES

Shifting from animal-based to plant-based diets could reduce colorectal cancer (CRC) incidence. Currently, the impacts of these dietary shifts on CRC risk are ill-defined. Therefore, we examined partial substitutions of red or processed meat with whole grains, vegetables, fruits or a combination of these in relation to CRC risk in Finnish adults.

METHODS

We pooled five Finnish cohorts, resulting in 43 788 participants aged ≥ 25 years (79% men). Diet was assessed by validated food frequency questionnaires at study enrolment. We modelled partial substitutions of red (100 g/week) or processed meat (50 g/week) with corresponding amounts of plant-based foods. Cohort-specific hazard ratios (HR) for CRC were calculated using Cox proportional hazards models and pooled together using random-effects models. Adjustments included age, sex, energy intake and other relevant confounders.

RESULTS

During the median follow-up of 28.8 years, 1124 CRCs were diagnosed. We observed small risk reductions when red meat was substituted with vegetables (HR 0.97, 95% CI 0.95 - 0.99), fruits (0.97, 0.94 - 0.99), or whole grains, vegetables and fruits combined (0.97, 0.95 - 0.99). For processed meat, these substitutions yielded 1% risk reductions. Substituting red or processed meat with whole grains was associated with a decreased CRC risk only in participants with < median whole grain intake (0.92, 0.86 - 0.98; 0.96, 0.93 - 0.99, respectively; pinteraction=0.001).

CONCLUSIONS

Even small, easily implemented substitutions of red or processed meat with whole grains, vegetables or fruits could lower CRC risk in a population with high meat consumption. These findings broaden our insight into dietary modifications that could foster CRC primary prevention.

Significant risk of second primary cancer among laryngeal squamous cell carcinoma patients even after 20 years

BACKGROUND

Evidence on the risk of second primary cancer (SPC) following primary laryngeal squamous cell carcinoma (LSCC) is limited, especially in Europe.

METHODS

Patients diagnosed with primary LSCC from 1953-2018 were retrieved from the Finnish Cancer Registry. A total of 6241 LSCC patients were identified adding to 49,393 person-years (PY) of follow-up until the end of 2019. Only one patient emigrated and was lost to follow-up. Both standardized incidence ratios (SIR) and excess absolute risk (EAR) per 1000 person-years at risk (PYR) of second primary cancer (SPC) were calculated relative to the general population. Only non-laryngeal SPCs diagnosed six months after diagnosis of primary LSCC were included.

RESULTS

A SPC was diagnosed in 1244 LSCC patients (20% of all LSCC patients) over the 65-year period, predominantly in men (92%, n = 1170). Out of all SPCs, 34% were diagnosed within 0.5 to 5 years and 66% after 5 years from primary LSCC. Among male patients, the overall SIR for SPC at any location was 1.61 (95% CI: 1.52-1.71), corresponding to 9.49 excess SPCs per 1000 PYR (95% CI: 8.19-11). The corresponding SIR for women was 1.47 (95% CI: 1.15-1.84), yielding 4.82 excess SPCs per 1000 PYR (95% CI: 2.36-9.84). The risk remained significant even after 20 years of follow-up (SIR for all 1.73, 95% CI: 1.49-2.01 and EAR 16.8 per 1000 PY, 11.88-23.75). The risk for SPC was also significantly elevated in all age groups, except <40. The highest SIRs were for SPCs arising in the mouth/pharynx (SIR for all 3.08, 95% CI: 2.36-3.95 and EAR 0.80 per 1000 PY, 0.55-1.15) and lungs (3.02, 2.75-3.30 and 5.90 per 1000, 5.13-6.78).

CONCLUSION

Patients with LSCC as primary cancer have a 60% excess risk for an SPC, especially for tobacco-associated cancers, remaining significantly elevated even decades after treatment.

Income disparities between adult childhood cancer survivors and their peers-A register-based cohort study from the SALiCCS research programme

BACKGROUND

Childhood cancer survivors face various adverse consequences. This Nordic register-based cohort study aimed to assess whether survivors of childhood cancer are more likely to have low income than their peers.

METHODS

We identified 17,392 childhood cancer survivors diagnosed at ages 0 to 19 between 1971 and 2009 with 83,221 age-, sex-, and country-matched population comparisons. Annual disposable income at ages 20 to 50 years was retrieved from statistical offices (for 1990-2017) and categorized into low income and middle/high income. The number of transitions between income categories were assessed using binomial regression analyses.

RESULTS

The prevalence of annual low income among childhood cancer survivors was 18.1% and 15.6% among population comparisons (risk ratio [RR] 1.17; 95% confidence interval [CI] 1.16-1.18). Compared to population comparisons, childhood cancer survivors were 10% (95% CI 8%-11%) less likely to transition from low to middle/high income and 12% (10%-15%) more likely to transition from middle/high to low income during follow-up. Among those initially in the low income category, survivors were 7% (95% CI 3%-11%) more likely to remain in the low income category. If the initial category was middle/high income, childhood cancer survivors were 10% (95% CI 8%-11%) less likely to remain in the middle/high income and 45% (37%-53%) more likely to transition to the low income category permanently.

CONCLUSIONS

Childhood cancer survivors are at higher risk for low income in adulthood than their peers. These disparities might be reduced by continued career counseling along with support in managing within the social security system.

Incidence of head and neck cancer among first-generation immigrants and their children in Finland

INTRODUCTION

Limited data exist regarding head and neck cancer (HNC) burden among immigrants who may have distinct characteristics, and hence different incidence rates from the general population. Variations in behavioral habits, cultural lifestyle, or diet may cause variations across different subgroups.

METHODS

The whole immigrant population of Finnish residents born abroad, and their children were retrieved for the years 1970-2017. First-generation immigrants are defined as individuals born abroad, excluding their children (even if born abroad). The study comprised 0.5 million first-generation immigrants and 0.3 million children, contributing to 6 million and 5 million person-years of follow-up, respectively. Standardized incidence ratios (SIR) and excess absolute risk (EAR) per 100,000 person-years at risk were calculated to quantify the risk of HNC among immigrants relative to the general Finnish population.

RESULTS

The overall risk of any HNC was not increased among first-generation male immigrants (SIR 1.00, 95% CI: 0.88-1.15), but significantly elevated for cancer of the pharynx (SIR 1.56, 95% CI: 1.22-1.95), and larynx (SIR 1.38, 95% CI: 1.02-1.83) and decreased for lip (SIR 0.38, 95% CI: 0.20-0.67). The increased risk of pharyngeal cancer was highest among male immigrants from Asia Pacific (SIR 4.21, 95% CI: 2.02-7.75). First-generation immigrant women had a significantly reduced risk of any HNC (SIR 0.45, 95% CI: 0.37-0.55), which remained even after stratification by site. We observed no increased risk of any HNC among the children of first-generation immigrants.

CONCLUSION

Healthcare professionals need to recognize the groups at higher HNC risk. Efforts to address the main etiological risk factors, such as smoking, are needed among the selected immigrant populations, that haven't yet reached similar decreasing trends, as in for example smoking, as the main population.NOVELTY AND IMPACTCurrently, globally, over 280 million people live outside their country of birth. Limited data exist regarding head and neck cancer (HNC) burden among immigrants who may have distinct characteristics and hence different incidence rates from the general population. Immigrant studies can provide novel data by shedding light on risk alterations and the pace of acculturation of different populations.

Use of health services one year before primary colorectal cancer

BACKGROUND

Colorectal cancer (CRC) patient pathways focus typically on periods after confirmed diagnosis and only limited data are available on pathways prior to cancer diagnosis. The aim of the study was to describe the use of health services (HS) one year before diagnosis among CRC patients in Finland. We also studied the role of sex, age, stage, and university hospital district in relation to the use of HS during the pre-diagnostic phase. This information is expected to bring light on the question why CRC is often not found in its early stages.

METHODS

Incident CRC cases (N = 3115) concerning year 2015 were retrieved from the Finnish Cancer Registry and linked with data from the Finnish Institute for Health and Welfare on primary or specialised care outpatient visits or inpatient episodes over one year prior to CRC diagnosis. We modelled the average number of HS events per patient using Poisson regression model with log-link. Change points for monthly HS event rates and 95% CIs one year before diagnosis were evaluated using Poisson broken line regression models.

RESULTS

Around 10% of patients diagnosed in 2015 had no events prior to cancer leaving 2816 CRCs in the study. Of all pre-diagnostic events (N = 23268), 86% were outpatient events and 14% inpatient episodes. More than half of the inpatient episodes (65%) started as urgent admissions. The use of HS started to increase 3-4 months before diagnosis. The average number of pre-diagnostic HS events per patient varied by sex, age, stage and university hospital district. Overall, men had more events per patient than women and older patients had more events than younger patients.

CONCLUSIONS

The amount of inpatient episodes starting as urgent admissions indicate potential bottlenecks in the access to health services. An increase in service use only 3-4 months prior to diagnosis reflects a need for advice both for health care professionals and the general population in recognising symptoms of CRC.

Incidence of cancer among Nordic police officers

Police work may expose officers to various circumstances that have potential for increasing their risk of cancer, including traffic-related air pollution, night shift work and radiation from radars. In this study, we examined the incidence of cancer among Nordic male and female police officers. We utilize data from the Nordic Occupational Cancer (NOCCA) project, which linked census data on occupations from Finland, Iceland, Norway and Sweden to national cancer registries for the period 1961 to 2005. We report standardized incidence ratios (SIR) and 95% confidence intervals (CI) of selected cancers for each country by sex, age and calendar period. The cohort included 38 523 male and 1998 female police officers. As compared with the general population, male police officers had a 7% (95% CI: 4-9%) excess cancer risk, with elevated SIRs for various cancer sites, including prostate (SIR 1.19, 1.14-1.25), breast (SIR 1.77, 1.05-2.80), colon (SIR 1.22, 1.12-1.32) and skin melanoma (SIR 1.44, 1.28-1.60). Conversely, male police officers had a lower risk of lung cancer than the general population (SIR 0.72, 0.66-0.77). In female police officers, the SIR for cancer overall was 1.15 (0.98-1.34), and there was a slight excess of cancers of the breast (SIR 1.25, 0.97-1.59) and colon (SIR 1.21, 0.55-2.30). In conclusion, cancer incidence among the police officers was slightly higher than in the general population. Notably, SIRs were elevated for cancer sites potentially related to night shift work, namely colon, breast and prostate cancer.

Early-onset grade 2-3 diffuse gliomas and schwannomas increase the risk of central nervous system tumors among the patients' relatives

Background

Central nervous system (CNS) tumors are a heterogeneous group of tumors that include several aggressive malignancies with a high mortality rate. This study aimed to evaluate the familial relative risk of CNS tumors in family members of early-onset index cases (probands) in and between diffuse glioma, non-diffuse glioma, meningioma, and other CNS tumors.

Methods

We retrieved tumor data from the Finnish cancer registry and familial relationships data from the population information system. We ascertained 5408 probands diagnosed with primary CNS tumors (age ≤40 years) between 1970 and 2012 in Finland. We report the standardized incidence ratios as a measure of familial aggregation using Poisson regression.

Results

The risk of early-onset diffuse glioma increased among siblings of probands with the same tumor [SIR 3.85, 95% confidence interval (CI): 1.66-7.59], with association mainly returning to grade 2-3 diffuse gliomas. Early-onset other CNS tumors were associated with an increased risk of other CNS tumors, early-onset meningioma, and late-onset diffuse glioma in 1st-degree relatives. The elevated risk of other CNS tumors was largely caused by schwannomas (SIR 59.44, 95% CI: 27.18-112.84 for 1st-degree relatives) and associated with neurofibromatosis. No tumor syndrome was associated with an increased risk of diffuse gliomas.

Conclusions

The early onset of grade 2-3 diffuse gliomas is associated with an increased risk of similar tumor entities. Early-onset schwannomas dramatically increase CNS tumor risk with a broader tumor-type profile. In future studies, it would be important to identify the underlying shared hereditary factors that contribute to the development of familial diffuse gliomas.

Sex-specific familial aggregation of cancers in Finland

Despite the fact that the effect of sex on the occurrence of cancers has been studied extensively, it remains unclear whether sex modifies familial aggregation of cancers. We explored sex-specific familial aggregation of cancers in a large population-based historical cohort study. We combined cancer and population registry data, inferring familial relationships from birth municipality-surname-sex (MNS) combinations. Our data consisted of 391,529 incident primary cancers in 377,210 individuals with 319,872 different MNS combinations. Cumulative sex-specific numbers of cancers were compared to expected cumulative incidence. Familial cancer risks were similar between the sexes in our population-wide analysis. Families with concordant cancer in both sexes exhibited similar sex-specific cancer risks. However, some families had exceptionally high sex-specific cumulative cancer incidence. We identified six families with exceptionally strong aggregation in males: three families with thyroid cancer (ratio between observed and expected incidence 184.6; 95% credible interval (95% CI) 33.1–1012.7, 173.4 (95% CI 65.4–374.3), and 161.4 (95% CI 29.6–785.7), one with stomach (ratio 14.4 (95% CI 6.9–37.2)), colon (ratio 15.5 (95% CI 5.7–56.3)) cancers and one with chronic lymphocytic leukaemia (ratio 33.5 (95% CI 17.2–207.6)). Our results imply that familial aggregation of cancers shows no sex-specific preference. However, the atypical sex-specific aggregation of stomach cancer, colon cancer, thyroid cancer and chronic lymphocytic leukaemia in certain families is difficult to fully explain with present knowledge of possible causes, and could yield useful knowledge if explored further.

Periodic trends in geographical variation of prostate cancer incidence and mortality in Finland between 1985 and 2019

BACKGROUND

Evaluation of regional variation of prostate cancer (PCa) incidence and PCa-specific mortality is essential in the assessment of equity in a national healthcare system. We evaluated PCa incidence and PCa-specific mortality between different municipalities and hospital districts in Finland over 1985-2019.

MATERIAL AND METHODS

Men diagnosed with PCa in Finland from 1985 through 2019 were retrieved from Finnish Cancer Registry. Age-standardized PCa incidence and mortality rates were estimated by municipality and hospital district as well as municipality urbanization, education, and income level using hierarchical Bayesian modeling. Standard deviations (SD) of the regional rates were compared between periods from 1985-1989 to 2015-2019.

RESULTS

We identified 123,185 men diagnosed with any stage PCa between 1985 and 2019. SD of PCa incidence rate (per 100,000 person-years) showed that the total variation of PCa incidence between different municipalities was substantial and varied over time: from 22.2 (95% CI, 17.1-27.8) in 1985-1989 to 56.5 (95% CI, 49.8-64.5) in 2000-2004. The SD of PCa mortality rate between all municipalities was from 9.0 (95% CI, 6.6-11.8) in 2005-2009 to 2.4 (95% CI, 0.9-4.8) in 2015-2019. There was a trend toward a lower PCa-specific mortality rate in municipalities with higher education level.

DISCUSSION

Regional variation in the incidence rate of PCa became more evident after initiation of PSA testing in Finland, which indicates that early diagnostic practice (PSA testing) of PCa has been different in different parts of the country. Variation in the national PCa mortality rate was indeed recognizable, however, this variation diminished at the same time as the mortality rate declined in Finland. It seems that after the initiation period of PSA testing, PSA has equalized PCa mortality outcomes in Finland.

Incidence trends of childhood central nervous system tumors in Finland 1990-2017

Introduction

Central nervous system (CNS) tumors are a leading cause of cancer-related morbidity and mortality in children. Our aim is to characterize incidence trends of pediatric CNS tumors in Finland over the last three decades.

Methods

Data on all benign and malignant incident CNS tumors diagnosed in children aged 0–14 years in 1990–2017 were extracted from the Finnish Cancer Registry and classified according to the 2016 WHO classification of CNS tumors. We analyzed age-standardized incidence rates (ASR) for pediatric CNS tumors overall and by sex, age, tumor histology, grade, and location using Poisson regression. We used joinpoint regression to evaluate changes in trends.

Results

Overall, 1117 pediatric CNS tumor cases were registered in Finland with a 1.2:1 male to female ratio. The average annual ASR was 4.3 per 100,000 person-years (95% CI 4.26, 4.34). The most common tumor type was pilocytic astrocytoma (30% of tumors), followed by medulloblastoma (10%) with incidence rates of 1.30 and 0.45 per 100,000 person-years, respectively. The overall incidence of pediatric CNS tumors increased by an annual percentage change (APC) of 0.8% (95% CI 0.2, 1.4). We observed no major changes in incidence trends of tumor histology groups or tumor location groups. The ASR of benign tumors increased by an APC of 1.0 (95% CI 0.1, 2.0).

Conclusions

Utilizing the high-quality and completeness of data in the Finnish Cancer registry, we found that the incidence of pediatric CNS tumors in Finland has increased slightly from 1990 until 2017. Although variations in diagnostic and registration practices over time might have affected the rates, the trend may also reflect a true increase in incidence.

Abstract 29: Autoimmune diseases and the risk of cancer

Background: Many autoimmune diseases (AD) are known to be associated with comorbidities, and certain ADs have been suggested to influence cancer risk. Immunosuppression and dysregulation of the immune system promote the development of certain cancers, particularly hematological malignancies. There is also evidence on an increased risk of several types of solid tumors among individuals with an AD. The aim of this population-based cohort study was to evaluate the risk of any cancer, except non-melanoma skin cancer, in 31 different ADs. We explored associations between both common (such as rheumatoid arthritis) and rare (such as Behcet’s disease) ADs and cancer.

Material and methods: The data consists of a population-based random sample of 2.5 million individuals who lived in Finland on January 1, 2000. It includes information on hospital diagnoses between 1970 and 2017 for each individual, with a total of 92 million hospital care records. There were 70 694 individuals with prevalent AD and 68 002 individuals with prevalent cancer. Those with prevalent cancer were removed from the analyses. Participants were followed up for subsequent occurrence of cancer, based on data from the nationwide cancer registry. We estimated relative risks (RRs) with 95% confidence intervals (CIs) using piecewise constant hazard regression models, adjusting for age, sex, and calendar period. Time since AD diagnosis was treated as a time-varying covariate.

Results: During the follow-up, 222 211 primary cancers were diagnosed, 18 409 with and 203 802 without a pre-existing AD. Overall, the risk of cancer was 2.02 (95% CI 1.93-2.12) for &lt;1 year since any AD diagnosis and 1.05 (1.03-1.07) for ≥10 years since diagnosis. The largest increase in cancer risk was observed for individuals with autoimmune hemolytic anemia, and there was evidence of a persisting risk even after 10 years since diagnosis (RR 8.53 (6.76-10.77) for &lt;1 year since diagnosis and 1.62 (1.18-2.24) for ≥10 years since diagnosis). Long-term impact on cancer risk was also observed for autoimmune vasculitis, Crohn's disease, discoid lupus erythematosus, pemphigus, psoriasis, systemic lupus erythematosus and ulcerative colitis. For individuals with these ADs, cancer risk was still elevated after 10 or more years after AD diagnosis.

Discussion: Cancer incidence was greatly dependent on AD duration. Cancer risk was increased soon (&lt;1 year) after AD diagnosis in 24 different ADs and elevated risks were still observed after ≥10 years in 8 ADs.

Cancer and comorbid diseases may have partly shared etiologies. Many lifestyle factors such as smoking, alcohol consumption, and obesity are established causes of many common diseases. Also, AD treatments may in some cases be tumorigenic. In conclusion, many ADs were associated with a significantly increased risk of cancer long after diagnosis, and this should be considered in patient counseling and monitoring. The findings also encourage search for shared risk factors underlying both diseases.

Citation Format: Sanna Heikkinen, Tomas Tanskanen, Lauri Sipilä, Janne Pitkäniemi. Autoimmune diseases and the risk of cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 29.

The impact of the COVID-19 pandemic on cancer diagnosis based on pathology notifications: A comparison across the Nordic countries during 2020

The severity of the COVID-19 pandemic and subsequent mitigation strategies have varied across the Nordic countries. In a joint Nordic population-based effort, we compared patterns of new cancer cases and notifications between the Nordic countries during 2020. We used pathology notifications to cancer registries in Denmark, the Faroe Islands, Finland, Iceland, Norway and Sweden to determine monthly numbers of pathology notifications of malignant and in-situ tumors from January to December 2020 compared to 2019 (2017-2019 for Iceland and the Faroe Islands). We compared new cancer cases per month based on unique individuals with pathology notifications. In April and May 2020, the numbers of new malignant cases declined in all Nordic countries, except the Faroe Islands, compared to previous year(s). The largest reduction was observed in Sweden (May: -31.2%, 95% CI -33.9, -28.3), followed by significant declines in Finland, Denmark and Norway, and a non-significant decline in Iceland. In Denmark, Norway, Sweden and Finland the reporting rates during the second half of 2020 rose to almost the same level as in 2019. However, in Sweden and Finland, the increase did not compensate for the spring decline (annual reduction -6.2% and -3.6%, respectively). Overall, similar patterns were observed for in-situ tumors. The COVID-19 pandemic led to a decline in rates of new cancer cases in Sweden, Finland, Denmark and Norway, with the most pronounced reduction in Sweden. Possible explanations include the severity of the pandemic, temporary halting of screening activities and changes in healthcare seeking behaviour.

Pairwise association of key lifestyle factors and risk of colorectal cancer: a prospective pooled multicohort study

BACKGROUND

Several lifestyle factors are associated with an increased risk of colorectal cancer (CRC). Although lifestyle factors co-occur, in most previous studies these factors have been studied focusing upon a single risk factor or assuming independent effects between risk factors.

AIM

To examine the pairwise effects and interactions of smoking, alcohol consumption, physical inactivity, and body mass index (BMI) with risk of subsequent colorectal cancer (CRC).

METHODS AND RESULTS

We used METCA cohort data (pooled data from seven population-based Finnish health behavior survey studies during years 1972-2015) consisting of 171 063 women and men. Participants' smoking, alcohol consumption, physical inactivity and BMI measures were gathered, and participants were categorized into those exposed and those not exposed. The incidence of CRC was modeled by Poisson regression with main and interaction effects of key lifestyle factors. The cohort members were followed-up through register linkage to the Finnish Cancer Registry for first primary CRC case until the end of 2015. Follow-up time was 1715, 690 person years. The highest pairwise CRC risk was among male smokers who had overweight (BMI ≥ 25 kg/m² ) (HR 1.75, 95% CI 1.36-2.26) and women who had overweight and consumed alcohol (HR 1.45, 95% CI 1.14-1.85). Overall, among men the association of lifestyle factors and CRC risk was stronger than among women. In men, both having overweight and being a smoker combined with any other adverse lifestyle factor increased CRC risk. Among women, elevated CRC risks were observed for those who were physically inactive and who consumed alcohol or had overweight. No statistically significant interactions were detected between pairs of lifestyle factors.

CONCLUSIONS

This study strengthens the evidence of overweight, smoking, and alcohol consumption as CRC risk factors. Substantial protective benefits in CRC risk can be achieved by preventing smoking, maintaining BMI to <25 kg/m² and not consuming alcohol.

Parity associates with chromosomal damage in uterine leiomyomas

Mechanical forces in a constrained cellular environment were recently established as a facilitator of chromosomal damage. Whether this could contribute to tumorigenesis is not known. Uterine leiomyomas are common neoplasms that display relatively few chromosomal aberrations. We hypothesized that if mechanical forces contribute to chromosomal damage, signs of this could be seen in uterine leiomyomas from parous women. We examined the karyotypes of 1946 tumors, and found a striking overrepresentation of chromosomal damage associated with parity. We then subjected myometrial cells to physiological forces similar to those encountered during pregnancy, and found this to cause DNA breaks and a DNA repair response. While mechanical forces acting in constrained cellular environments may thus contribute to neoplastic degeneration, and genesis of uterine leiomyoma, further studies are needed to prove possible causality of the observed association. No evidence for progression to malignancy was found.

Probability of live birth after IVF/ICSI treatments in female early onset cancer survivors: a Finnish population-based registry study

STUDY QUESTION

Does the probability of a live birth after fresh IVF/ICSI cycles with autologous oocytes differ in early onset female cancer survivors compared to their siblings?

SUMMARY ANSWER

The probability of a live birth was similar in female cancer survivors and siblings after four fresh IVF/ICSI cycles.

WHAT IS KNOWN ALREADY

Fertility preservation strategies are rapidly being developed to help female cancer patients who wish to have children later. However, there are only a few studies available on fertility treatments and following live births in female cancer survivors before fertility preservation strategies became available. In one of them, the probability of a live birth was reduced after assisted reproductive technology with autologous oocytes in cancer survivors compared to siblings.

STUDY DESIGN, SIZE, DURATION

In this retrospective, register-based study, data from Finnish registers on cancer, birth and prescribed medications were merged to identify 8944 female cancer survivors (diagnosed with cancer between 1953 and 2012 at the age of 0-40 years) and 9848 female siblings of survivors eligible for IVF/ICSI treatments between January 1993 and December 2012.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Fresh IVF/ICSI cycles and following live birth rates (LBRs) within 22-48 weeks in cancer survivors and siblings at the age of 20-41 years were identified. A binomial regression model with log-link function was used to calculate risk ratio (RR) for live births after fresh IVF/ICSI cycles in survivors compared to siblings, adjusting for attained age and calendar time. A Poisson regression model was used to estimate incidence rate ratios (IRRs) for an IVF/ICSI treatment, as well as overall live births, including both pregnancies after fertility treatments and spontaneous pregnancies, in survivors compared to siblings.

MAIN RESULTS AND THE ROLE OF CHANCE

We observed an overall decreased LBR, irrespective of IVF/ICSI treatments, in cancer survivors compared to siblings (IRR 0.68, 95% CI 0.64-0.71). All in all, 179 (2.0%) survivors and 230 (2.3%) siblings were prescribed fertility drugs for IVF/ICSI treatments (IRR 0.72, 95% CI 0.62-0.84). For the first fresh IVF/ICSI cycle, the LBR was 17.2% among survivors and 15.7% among siblings (RR 1.13, 95% CI 0.72-1.87). The mean LBR after four fresh IVF/ICSI cycles was not statistically different in survivors compared to siblings.

LIMITATIONS, REASONS FOR CAUTION

In this study, only IVF/ICSI treatments with autologous oocytes were included. The probability of a live birth after a frozen embryo transfer or oocyte donation could not be evaluated in this study. Information on miscarriages, extrauterine pregnancies or termination of pregnancies was not available.

WIDER IMPLICATIONS OF THE FINDINGS

For those early onset cancer survivors, who received IVF/ICSI treatments, the probability of live birth was not different from siblings who received IVF/ICSI treatments. However, an overall decreased LBR, irrespective of IVF/ICSI treatments, was observed in cancer survivors compared to siblings, indicating that cancer survivors receiving IVF/ICSI treatments in our study consisted of a selected group with at least a moderate ovarian reserve.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by a grant from the Cancer Foundation (Finland) (grant number 130079) and by a grant from LähiTapiola. The authors have no potential conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Incidence trends and risk factors of lung cancer in never smokers: Pooled analyses of seven cohorts

The trends in incidence of lung cancer in never smokers are unclear as well as the significance of risk factors. We studied time trends in the incidence and risk factors of lung cancer in never smokers in Finland in a large, pooled cohort. We pooled data from seven Finnish health cohorts from the period between 1972 and 2015 with 106 193 never smokers. The harmonised risk factors included education, alcohol consumption, physical activity, height and BMI. We retrieved incident lung cancers from the nation-wide Finnish Cancer Registry. We estimated average annual percent change (AAPC) and the effects of risk factors on cause-specific hazard ratios (HRs) of lung cancer using Poisson regression. We detected 47 lung cancers in never smoking men (n = 31 859) and 155 in never smoking women (n = 74 334). The AAPC of lung cancer incidence was -3.30% (95% confidence interval [CI]: -5.68% to -0.88%, P = .009) in never smoking men and 0.00% (95% CI: -1.57% to 1.60%, P = .996) in never smoking women. Of the five studied risk factors only greater height in women had a statistically significant increased risk of lung cancer (multivariate HR = 1.84, 95%CI: 1.08 to 3.12). It is plausible that tobacco control measures focused on working places have reduced passive smoking among men more than among women, which could explain the declining trend in lung cancer incidence in never smoker men but not in never smoker women. As tobacco control measures have not been targeted to domestic environments, it is likely that women's exposure to passive smoking has continued longer.

Familial aggregation of early-onset haematological malignancies

Population-based studies on familial aggregation of haematological malignancies (HM) have rarely focused specifically on early-onset HMs. We estimated standardized incidence ratios (SIR) and cumulative risks of relatives with Hodgkin lymphoma (HL), non-Hodgkin lymphomas (NHL), acute lymphoblastic leukaemia/lymphoma (ALL/LBL) and acute myeloid leukaemia (AML) when index persons and relatives were diagnosed with early-onset HM. A total of 8791 patients aged ≤40 years and diagnosed with primary HM in Finland from 1970 to 2012 were identified from the Finnish Cancer Registry and their 75 774 family members were retrieved from the population registry. SIRs for concordant HMs were elevated among first-degree relatives in all of the most common HMs of children and adolescents and young adults (AYA). The risk was highest among siblings with HL (SIR 9·09, 95% confidence interval 5·55-14·04) and AML (8·29, 1·00-29·96). HL also had the highest cumulative risk for siblings at ≤40 years of age (0·92% vs. 0·11% in the population). In conclusion, significantly elevated SIRs indicate a role of shared aetiological factors in some families, which should be noted in the clinical setting when caring for patients with early-onset HMs.

Decreasing trend and changing indications of hysterectomy in Finland

INTRODUCTION

Hysterectomy has been one of the most common surgical procedures in women in Finland. We studied the population-based trends of hysterectomy and its indications from 1986 to 2017.

MATERIAL AND METHODS

A retrospective population-based cohort was created from the Care Register for Health Care by identifying women who had a hysterectomy from 1986 to 2017 and calculating the number of women from the Digital and Population Data Services Agency. We estimated the number and incidence of hysterectomy by period and age as well as by indication. We considered the primary diagnosis at the time of surgery as the indication of hysterectomy.

RESULTS

The number of hysterectomies increased from 7492 procedures in 1986 to 12 404 procedures in 1998, and reduced substantially after that to 5971 procedures in 2017, the turning point being in 1999. The incidence rate of hysterectomy has decreased on average by 2.5% annually from 432.6 per 100 000 women in 1998-2001 to 224.5 per 100 000 women in 2014-2017. The median age at the time of hysterectomy has increased from 51 years in 1998-2001 to 55 years in 2014-2017. The cumulative burden of hysterectomy by age of 60 years has nearly halved from the first 4-year period (23%) to the last (12%). After 2010, the most common indication has been genital prolapse and incontinence, whereas earlier it was uterine fibroids.

CONCLUSIONS

The number and incidence of hysterectomies have fluctuated during the observation period 1986-2017 and decreased considerably during the past 17 years in Finland. This is probably a result of the availability of hormonal and other conservative treatment options for bleeding disorders and uterine fibroids. As hysterectomy practically removes the risk for endometrial cancer, the change in hysterectomy incidence over time emphasizes the importance of correcting endometrial cancer incidence according to hysterectomy incidence.

Variation in cancer survival between hospital districts and within them in Finland

BACKGROUND

Monitoring regional variation in population-based cancer survival is useful for assessing equity in national health-care system. This study quantifies variation in survival between municipalities and hospital districts responsible for primary care and for specialised care, respectively, in Finland.

MATERIAL AND METHODS

Five-year relative survival of 11 cancers and close to 700,000 patients was estimated by municipality in Finland over 1962-2016 using hierarchical Bayesian modelling. Variation (i) between hospital districts, (ii) between municipalities within hospital districts, and (iii) between all municipalities (total variation) were quantified by the standard deviation of 5-year relative survival standardised by the average survival level.

RESULTS

In 2007-2016, the largest variation in 5-year relative survival between all municipalities was in stomach, prostate, kidney and liver cancer and skin melanoma. In male skin melanoma, prostate, and kidney cancer and in male and female pancreatic cancer, there was substantial and statistically significant variation between hospital districts, too. Variation within hospital districts was on average 67% (95% posterior interval [58%,76%]) out of the total variation and had decreased by 18% [2%, 33%] from 1997-2006.

CONCLUSION

The decrease in variation within hospital districts suggests that equity in diagnostics and primary care has improved in Finland. However, the variation between hospital districts in skin melanoma, prostate and kidney cancer reflects differences in early diagnostics. In pancreatic cancer, substantial variation between hospital districts may relate to regional differences in the accessibility and the quality of cancer treatments.

Familial aggregation of testicular cancer among early-onset cancer survivors. A prospective observational cohort data from Finland

Testicular cancer (TC) is the most common form of cancer in men aged 15-35 years. Familial risk for TC is among highest of all cancers.

MATERIAL AND METHODS

A prospective observational cohort of 9111 relatives in 2,188 families of early-onset TC patients, called probands, diagnosed at age ≤40 years in Finland between 1970 and 2012. Standardized incidence ratios (SIR) were used as measures of familial aggregation for early-onset (≤40 years) TC. Follow-up ended at diagnosis of TC, death or 31 December 2014 whichever earliest.

RESULTS

Among first-degree relatives of early-onset TCs, in all 12 early-onset TC cases (0.24%) were diagnosed over the follow-up; the SIR for any first-degree relative was 4.59 (95% confidence interval (CI): 2.37-8.01) and for brothers the SIR was 6.51 (95% CI 3.12-11.96).

DISCUSSION

Familial aggregation of TC shows substantial risk for early-onset TC among first-degree relatives of early-onset TC patients in Finland. This is important to acknowledge to avoid diagnostic delay especially of TC.

Familial cancer risk in family members and spouses of patients with early-onset head and neck cancer

BACKGROUND

Reported patterns of familial aggregation of head and neck cancer (HNC) vary greatly, with many studies hampered by the limited number of subjects.

METHODS

Altogether 923 early-onset (≤40 years old) HNC probands, their first-degree relatives, spouses, and siblings' offspring were ascertained. Cumulative risk and standardized incidence ratios (SIRs) were estimated.

RESULTS

Of all early-onset HNC families, only 21 (2.3%) had familial HNC cancers at any age and less than five familial early onset HNC cancers among first-degree relatives. The cumulative risk of HNC for siblings by age 60 (0.52%) was at population level (0.33%). No increased familial risk of early-onset HNC could be discerned in family members (SIR 2.68, 95% CI 0.32-9.68 for first-degree relatives).

CONCLUSIONS

Our study indicates that the cumulative and relative familial risk of early-onset HNC is modest in the Finnish population and, at most, only a minor proportion of early-onset HNCs are due solely to inherited genetic mutations.

Childhood cancer mortality and survival in immigrants: A population-based registry study in Finland

Immigration in Europe has increased considerably over the past decades with the immigrant population similarly expanding in Finland. Our aim was to study childhood cancer mortality and survival in immigrants. In all, 4,437 patients diagnosed with cancer under the age of 20 years between 1990 and 2009 were identified from the Finnish Cancer Registry and their parents from the Population Register Center. Information on demographic factors was obtained from Statistics Finland. Poisson regression modeling was used to estimate hazard ratios (HRs) for cancer deaths. The life table method and the log rank test were used in survival analysis. Patients or parents of foreign background and born abroad had higher 5-year mortality (patient HR 2.03, 95% CI 1.18-3.49; maternal HR 2.11, 95% CI 1.46-3.04; paternal HR 1.85, 95% CI 1.29-2.66) compared to those of Finnish background and born in Finland. Childhood cancer survival in 5-year follow-up was higher if the mother (83% vs. 68%) or the father (83% vs. 70%) were of Finnish background and born in Finland. Despite equal access to public health care, we observed significant differences in childhood cancer mortality and survival by background. Cultural differences, linguistic obstacles and difficulties in navigating the health care system may contribute, along with genetic and biologic factors. Offering tailored information and taking cultural and linguistic aspects into account is necessary when diagnosing and treating patients from different ethnic backgrounds who have not yet integrated into the local culture and health care system.

Glioblastoma survival is improving despite increasing incidence rates: a nationwide study between 2000 and 2013 in Finland

BACKGROUND

We assessed population-level changes in glioblastoma survival between 2000 and 2013 in Finland, with focus on elderly patients (>70 y) in order to assess if changes in treatment of glioblastoma are reflected also in population-based survival rates.

METHODS

We identified all patients (age ≥18 y) from the Finnish Cancer Registry (FCR) with a histopathological diagnosis of primary glioblastoma in 2000-2013. Patients were followed up until December 2015. The accuracy of register-based search of glioblastoma patients was internally validated. We report age-standardized relative survival ratios and relative excess risks (RERs) of death in 2000-2006 (pre-period) and 2007-2013 (post-period).

RESULTS

We identified 2045 glioblastoma patients from the FCR. The accuracy of the FCR-based search was 97%. Median age was 63.3 years, and 42% were women. Incidence increased on average by 1.6% (P = 0.004) and median age by 0.4 years per calendar year. Between the pre- and post-periods, the proportion of patients >70 years increased from 24% to 27%. In >70-year-old patients, the median survival time increased from 3.6 months in 2000-2006 to 4.5 months in 2007-2013 (RER 0.82, 95% CI: 0.68-0.98). In ≤70-year-old patients, the median survival time increased from 9.3 months in 2000-2006 to 11.7 months in 2007-2013 (RER 0.74, 95% CI: 0.67-0.82).

CONCLUSION

Despite the increased proportion of elderly glioblastoma patients, population-level survival of glioblastoma patients has improved since the year 2000. However, increasing incidence, increasing age of patients, and poor survival in elderly are alarming, and future studies should perhaps focus more on elderly.

Linking population-based registries to identify familial cancer risk in childhood cancer

BACKGROUND

Linked population-based registries provide a unique source for identification of new family cancer syndromes and for elucidating risk of early-onset cancer in close relatives of cancer patients.

METHODS

Using the Finnish Cancer Registry, we identified 9078 probands who had been diagnosed with cancer at <21 years of age between 1970 and 2012. Siblings, offspring, parents, nephews, and nieces of probands were identified from the Population Registry. Childhood and young adult (ChYA) cancer diagnoses (age 0-39 years) in relatives were identified by linking to the Finnish Cancer Registry. The relative risk of ChYA cancer in family members of probands was estimated using standardized incidence ratios (SIRs).

RESULTS

Among 58,010 family members of the 9078 probands, 363 ChYA cancers were diagnosed, 324 of which were expected (SIR, 1.12; 95% CI, 1.01-1.24). The risk of ChYA cancer was elevated both in offspring (SIR, 2.25; 95% CI, 1.51-3.24) and in siblings (SIR, 1.17; 95% CI, 1.01-1.36). Offspring of probands with retinoblastoma were at highest risk (SIR, 75.85; 95% CI, 32.75-149.45); risks were also elevated for siblings of probands with lymphoma (SIR, 1.62; 95% CI, 1.14-2.25). Known cancer predisposition syndromes were observed in 29 (66%) of 44 sibling pairs with cancers diagnosed at <21 years of age and in 20% of the 135 families with a childhood cancer proband whose sibling was diagnosed with a young adult malignancy.

CONCLUSION

Linked population-based registry data indicate a modestly increased risk of ChYA in relatives of children with cancer. Some of the observed cancer clusters in the cohort suggest novel patterns and familial cancer syndromes.

Survival and mortality of elderly men with localized prostate cancer managed with primary androgen deprivation therapy or by primary observation

BACKGROUND

Androgen deprivation therapy (ADT) remains a primary treatment for localized prostate cancer (PCa) even though there is no evidence that its use is beneficial in the absence of curative treatment.

METHODS

Men aged ≥70 years (n = 16,534) diagnosed with localized PCa from 1985 to 2014 and managed either with primary observation or ADT in the absence of curative treatment were included. The cases were identified from the population-based Finnish Cancer Registry. We estimated the standardized mortality ratios (SMR) for overall mortality by treatment group. We determined the relative risk (RR) of PCa-specific mortality (PCSM) and other-cause mortality between the two treatment groups. Survival was determined using the life table method. Two age groups (70-79 years and ≥ 80 years) and three calendar time cohorts (1985-1994, 1995-2004, and 2005-2014) were compared following adjustment of propensity score matching between the treatment groups with four covariates (age, year of diagnosis, educational level, and hospital district). Follow-up continued until death or until December 31, 2015.

RESULTS

Patients in the observation group had lower overall SMRs than those in the ADT group in both age cohorts over the entire study period. PCSM was higher in men aged 70-79 years undergoing primary ADT compared to those managed by observation only (RR: 1.70, 95% confidence interval [CI]: 1.29-2.23 [1985-1994]; RR 1.55, 95% CI: 1.35-1.84 [1995-2004]; and RR 2.71, 95% CI: 2.08-3.53 [2005-2014]); p = 0.005 for periodic trend. A similar trend over time was also observed in men aged > 80 years; (p for age-period interaction = 0.237). Overall survival was also higher among men in their 70's managed by observation compared to those undergoing ADT.

CONCLUSIONS

Primary ADT within four months period from diagnosis is not associated with improved long-term overall survival or decreased PCSM compared to primary conservative management for men with localized PCa. However, this observational study's conclusions should be weighted with confounding factors related to cancer aggressiveness and comorbidities.

Disparities in glioblastoma survival by case volume: a nationwide observational study

Introduction

High hospital case volumes are associated with improved treatment outcomes for numerous diseases. We assessed the association between academic non-profit hospital case volume and survival of adult glioblastoma patients.

Methods

From the nationwide Finnish Cancer Registry, we identified all adult (≥ 18 years) patients with histopathological diagnoses of glioblastoma from 2000 to 2013. Five university hospitals (treating all glioblastoma patients in Finland) were classified as high-volume (one hospital), middle-volume (one hospital), and low-volume (three hospitals) based on their annual numbers of cases. We estimated one-year survival rates, estimated median overall survival times, and compared relative excess risk (RER) of death between high, middle, and low-volume hospitals.

Results

A total of 2,045 patients were included. The mean numbers of annually treated patients were 54, 40, and 17 in the high, middle, and low-volume hospitals, respectively. One-year survival rates and median survival times were higher and longer in the high-volume (39%, 9.3 months) and medium-volume (38%, 8.9 months) hospitals than in the low-volume (32%, 7.8 months) hospitals. RER of death was higher in the low-volume hospitals than in the high-volume hospital (RER = 1.19, 95% CI 1.07–1.32, p = 0.002). There was no difference in RER of death between the high-volume and medium-volume hospitals (p = 0.690).

Conclusion

Higher glioblastoma case volumes were associated with improved survival. Future studies should assess whether this association is due to differences in patient-specific factors or treatment quality.

Electronic supplementary material

The online version of this article (10.1007/s11060-020-03428-5) contains supplementary material, which is available to authorized users.

Risk of second primary cancer in oral squamous cell carcinoma

BACKGROUND

The incidence and survival of oral squamous cell carcinoma (OSCC) patients have increased in recent years. Understanding their long-term survival aspects is essential for optimal treatment and follow-up planning. Almost one in five cancers diagnosed occurs nowadays in individuals with a previous diagnosis of cancer.

METHODS

Patients diagnosed with primary OSCC during 1953-2015 were retrieved from the Finnish Cancer Registry. Both standardized incidence ratios (SIR) and excess absolute risk (EAR) per 1000 person-years at risk (PYR) of second primary cancer (SPC) were calculated relative to the general population.

RESULTS

Among 6602 first primary OSCC patients there were 640 (10%) SPCs. The SIR for SPCs was 1.85 (95% CI: 1.71-1.99, P < .001) corresponding to an EAR of 8.78 (95% CI: 7.29-10.26).

CONCLUSIONS

Health care professionals should be aware of the second primary cancer risk after management of primary OSCC and patients need to be counseled about this phenomenon.

Maternal diabetes and risk of childhood cancer in the offspring

An association between maternal diabetes, its medication and childhood cancer has not been previously explored in a registry-based setting. With a case-control design, we aimed to explore whether maternal diabetes is associated with an increased risk of childhood cancer in the offspring. Combining data from population-based registries, we analyzed a total of 2,029 cases, that is, persons with childhood cancer diagnosed under the age of 20 years between years 1996-2014 and a total of 10,103 matched population controls. The mothers of the cases/controls and their diagnoses of diabetes (DM) before/during pregnancy as well as their insulin/metformin prescriptions during pregnancy were identified. Conditional logistic regression modeling was used to analyze the risk of childhood cancer. The OR for childhood cancer among those exposed to any maternal diabetes was 1.32 (95% CI 1.14-1.54) compared to the offspring of the nondiabetic mothers. The effect of maternal diabetes on the risk of childhood cancer remained elevated even after adjusting for maternal age, parity and smoking. Our data suggest that maternal diabetes medication may reduce the risk for childhood cancer (adjusted OR 0.83, 95% CI 0.36-1.94), especially in gestational diabetes (adjusted OR 0.26, 95% CI 0.05-1.25), compared to the diabetic mothers without medication. The risk of childhood leukemia was significantly higher among children exposed to any maternal diabetes (OR 1.36, CI 1.04-1.77) compared to the unexposed. Maternal diabetes appears to be associated with an increased risk of childhood cancer in the offspring. The possible risk-reducing effect of an exposure to diabetes medication on offspring cancer risk warrants further investigation.

Vasectomy and the risk of prostate cancer in a Finnish nationwide population-based cohort

INTRODUCTION & OBJECTIVES

There are conflicting reports on the association of vasectomy and the risk of prostate cancer (PCa). Our objective was to evaluate the association between vasectomy and PCa from a nationwide cohort in Finland.

MATERIALS & METHODS

Sterilization registry of Finland and the Finnish Cancer Registry data were utilized to identify all men who underwent vasectomy between years 1987-2014 in Finland. Standard incidence ratio (SIR) for PCa as well as all-cause standardized mortality ratios (SMR) were calculated.

RESULTS

We identified 38,124 men with vasectomy with a total of 429,937 person-years follow-up data. The median age at vasectomy was 39.7 years (interquartile range [IQR] 35.9-44.0), after vasectomy PCa was diagnosed in 413 men (122 cases 0-10 years, 219 cases 10-20 years and 72 cases >20 years from vasectomy). SIR for PCa for the vasectomy cohort was 1.15 (95% CI: 1.04-1.27). By the end of follow-up, 19 men had died from PCa, while the expected number was 20.5 (SMR 0.93 [95%CI: 0.56-1.44]). The overall mortality was decreased (SMR 0.54 [95%CI: 0.51-0.58]) among men with vasectomy.

CONCLUSION

We found a small statistically significant increase in PCa incidence after vasectomy, but in contrast the mortality of vasectomized men was significantly reduced. This may be due to higher likelihood of vasectomized men to undergo prostate-specific antigen testing, having healthier general lifestyle and other biological factors e.g. high reproductive fitness.

Trends of colorectal cancer incidence by education and socioeconomic status in Finland

Background: The aim of this study was to investigate if the incidence of colorectal cancer (CRC) is associated with education and socioeconomic status (SES) in Finland, and if there are any changes in incidence differences between the groups over the period 1976-2014.Material and methods: CRC cases (N = 77,614) were retrieved from the Finnish Cancer Registry and linked with information on the education level and SES from Statistics Finland. We used Poisson regression model to quantify differences in incidence rates between the groups, and to assess changes over calendar time.Results and conclusions: Colon cancer incidence was higher among the highly educated, than in those with basic education. Similar differences were observed by SES in men. Incidence rates increased steeply over time among men with basic education (from 16.7/100,000 in 1976-1979 to 31.8 in 2010-2014), resulting in narrowed differences between the groups (p < .001). Incidence trends of proximal and distal colon and rectal cancer in men showed similar patterns. Heterogeneity across time periods by SES was observed only in colon cancer incidence in men (p = .009). No such large differences were detected in women. Steep increase in colon cancer incidence in men with basic education, and the respective persistent high incidence in the highly educated highlights the importance of focusing the preventive measures on modifiable lifestyle factors in order to reduce CRC incidence and to narrow the educational and socioeconomic health differences.

Risk of cancer in first-degree relatives of childhood cancer patients: A linked longitudinal population-based registry study

1522

Background: Population based data on risk of cancer in relatives of childhood cancer patients are sparse. Using linked population-based registries, we set out to evaluate risk of early onset cancer in first-degree relatives of childhood cancer patients. Methods: We queried the Finnish Cancer Registry and ascertained a cohort of 9135 individuals diagnosed with at least one cancer under the age of 21 years between 1970 and 2012. We then went on to identify a total of 58,211 unique first- and second-degree relatives by linking to the Central Population Registry. Relatives were then linked back to the annually updated Finnish Cancer Registry to identify cancer diagnoses in siblings, offspring and parents of childhood cancer patients, restricting to cancers occurring under the age of 40. Risk of cancer in relatives of the index case was estimated using standardized incidence ratios (SIRs) comparing cancer age and period specific incidence in relatives to that of the general population. Results: A total of 288 cancers were diagnosed in relatives during the 900,907 years of follow-up, while 266 cancers were expected. The overall risk of cancer in siblings of childhood cancer patients was elevated (SIR 1.18 95% CI 1.00-1.39). 144 of the childhood cancer patients were identified as having a sibling additional to index case with a diagnosis of cancer at age < 40; 44 of these 144 also had a parent with early onset cancer. The risk of early onset cancer was elevated in offspring overall (SIR 1.79 95%CI 1.05-2.81) and in offspring of retinoblastoma, malignant bone tumor and neuroblastoma patients. Siblings of lymphoma patients were at elevated risk of early cancer, and the mothers of 11 of 27 sibling pairs (lymphoma + cancer < 40 yo) also had cancer at age < 40. Conclusions: Linked registries allow family history of cancer to be evaluated across multiple relatives and to be longitudinally updated. Results are generally reassuring with regard to risk of cancer in relatives of childhood cancer patients. Elevated risk in relatives of retinoblastoma and malignant bone tumor patients are in line with the known cancer syndromes associated with these tumor types, and lymphoma and neuroblastoma families need further analysis.

Correction: Association of symptoms and interval breast cancers in the mammography-screening programme: population-based matched cohort study

The authors report that the labels indicating the symptom types and no symptom lines in the original version of Figure 2 were missing. The correct version of Figure 2 with the labels included is provided below.

Pediatric malignancies in neurofibromatosis type 1: A population-based cohort study

Neurofibromatosis type 1 (NF1) is a cancer predisposition syndrome with an incidence of 1:2,000. Patients with NF1 have an increased cancer risk and mortality, but there are no population‐based cohort studies specifically investigating the risk of childhood malignancies. We used the Finnish NF1 cohort to analyze the incidence, risk and prognosis of malignancies in NF1 patients <20 years of age. Persons born in 1987–2011 were included, and 524 persons were followed through the files of the Finnish Cancer Registry from birth up to age 20 years. This amounted to 8,376 person years. Fifty‐three patients had cancer <20 years of age, yielding a standardized incidence ratio (SIR) of 35.6. The most frequent location of pediatric cancers was the central nervous system (CNS); there were 45 cases and the SIR was 115.7. Exclusion of 22 optic pathway gliomas (OPGs) gave an SIR of 59.1 for the CNS and 21.6 for all cancers. There were nine malignant peripheral nerve sheath tumors (MPNSTs); their cumulative risk was 2.7% by age 20. No cases of leukemia were observed. NF1 patients showed considerable excess mortality with a standardized mortality ratio (SMR) of 73.1. The survival of NF1 patients with CNS tumors other than OPGs did not differ from that of non‐NF1 controls (HR 0.64, 95% CI 0.23 to 1.76). In conclusion, brain tumors in childhood and MPNSTs in adolescence are malignancies of major concern in patients with NF1. The risk for myeloid malignancies may not be as high as suggested in the literature.

What's new?

Patients with neurofibromatosis type 1 (NF1) are known to have a high risk of various cancers. What has not been well‐studied, however, are the types of cancers that are most common among children with NF1, and how those cancers impact mortality. In this cohort study, the authors found that malignancies do cause increased mortality in patients under age 20. Brain tumors in childhood and malignant peripheral nerve sheath tumors (MPNSTs) in adolescence are of particular concern. On the other hand, the risk of myeloid malignancies may be lower than previously assumed.

Cancer incidence and mortality patterns in women with breast symptoms in the mammography screening programme: A matched cohort analysis

Efforts to reduce mortality through early detection and diagnosis has intensified in the recent decade. An important risk factor, 'breast symptoms' reported by women during screening visit, remains overlooked. In this population based matched cohort study using Finnish National Breast Cancer Screening Program (FNBCSP), we assessed the association between breast symptoms reported at screening visit and the risk of cancer incidence and breast cancer mortality and all-cause mortality followed-up over a period of 24 years. For each visit with symptoms, non-symptomatic controls were matched (1:1 for lump and retraction; 1:2 for nipple discharge) based on age at screening visit, year of invitation, number of invited visits, and municipality of invitation. Women who reported lump or retraction had about two-fold risk of breast cancer incidence, three-fold risk of breast cancer mortality and all-cause mortality respectively as compared to women without respective symptoms (p-value<0.05). We found a substantial difference (p-value<0.05) in mortality rates throughout the follow-up period between symptomatic and asymptomatic group. In absolute terms, after the follow-up period for women who reported lump, 180 died from breast cancer as compared to 70 deaths in those without lump, per 10,000 person-years of follow-up, and 315 versus 160 all-cause deaths per 10,000 person-years in women with and without lump respectively. our study provides comprehensive evidence that women with breast symptoms remain in a higher risk of dying over a very long period. The findings indicate needs to develop improvements in the guidelines for screening and clinical services for women presenting with symptoms.

Sex differences in faecal occult blood test screening for colorectal cancer

Background

This analysis of patients in a randomized population‐based health services study was done to determine the effects of faecal occult blood test (FOBT) screening of colorectal cancer (CRC) in outcomes beyond mortality, and to obtain explanations for potential sex differences in screening effectiveness.

Methods

In the Finnish FOBT screening programme (2004–2011), people aged 60–69 years were randomized into the screening and control arms. Differences in incidence, symptoms, tumour location, TNM categories, non‐vital outcomes and survival in the screening and control arms were analysed.

Results

From 321 311 individuals randomized, 743 patients with screening‐detected tumours and 617 control patients with CRC were analysed. CRC was less common in women than in men (0·34 versus 0·50 per cent; risk ratio (RR) 0·82, 95 per cent c.i. 0·74 to 0·91) and women were less often asymptomatic (16·7 versus 22·0 per cent; RR 0·76, 0·61 to 0·93). Women more often had right‐sided tumours (32·0 versus 21·3 per cent; RR 1·51, 1·26 to 1·80). Among men with left‐sided tumours, those in the screening arm had lower N (RR 1·23, 1·02 to 1·48) and M (RR 1·57, 1·14 to 2·17) categories, as well as a higher overall survival rate than those in the control arm. Furthermore among men with left‐sided tumours, non‐radical resections (26·2 versus 15·7 per cent; RR 1·67, 1·22 to 2·30) and postoperative chemotherapy sessions (61·6 versus 48·2 per cent; RR 1·28, 1·10 to 1·48) were more frequent in the control arm. Similar benefits of screening were not detected in men with right‐sided tumours or in women.

Conclusion

Biennial FOBT screening seems to be effective in terms of improving several different outcomes in men, but not in women. Differences in incidence, symptoms and tumour location may explain the differences in screening efficacy between sexes.

Only of benefit in men

Association of symptoms and interval breast cancers in the mammography-screening programme: population-based matched cohort study

Background

We assessed the association between symptoms reported at breast cancer screening visits and interval cancers (ICs) in a prospective manner.

Methods

This population-based matched cohort study uses data of the Finnish National Breast Cancer Screening Programme that invites women aged 50–69 years old during 1992–2012. Subjects who attended screening with symptoms were matched with asymptomatic reference cohorts based on age at screening visit, year of invitation, number of invited visits and municipality of invitation. The primary outcome was ICs.

Results

Women with a lump had a threefold (hazard ratio 3.7, 95% confidence interval (CI) 3.0–4.6) risk of ICs and a higher risk (hazard ratio 1.7, 95% CI 1.4 to 2.0) at the subsequent visit compared with those without a lump. The fatal interval cancer risk increased by 0.39 per 1000 screens with a lump. The cumulative incidences of interval cancer increased within a month of a mammography-negative visit with a lump and after about 6 months of the visit with retraction or nipple discharge.

Conclusion

Women with breast symptoms have a clearly increased risk of interval breast cancer after the screening visit. Our findings indicate the need for different screening strategies in symptomatic women.

Impact of parental socioeconomic factors on childhood cancer mortality: a population-based registry study

INTRODUCTION

Parental socioeconomic status has been proposed to have an influence on childhood cancer mortality even in high-income countries. Our study investigated the influence of parental socioeconomic factors on childhood cancer mortality.

MATERIAL AND METHODS

We identified 4437 patients diagnosed with cancer under the age of 20 from 1990 to 2009 and their parents from the Finnish cancer and central population registers. Information on death from primary cancer during five-year follow-up and parental socioeconomic factors was obtained from Statistics Finland. Poisson regression modeling was used to estimate hazard ratios (HRs) for factors related to cause-specific mortality and recursive tree based survival analysis to identify important risk factors and interactions.

RESULTS

Mortality was lower in the highest quartile of combined parental disposable income (HR 0.68, CI 95% 0.52-0.89) compared to the lowest quartile. In the most recent diagnostic period from 2000 to 2009, highest attained education of either parent being post-secondary predicted lower mortality (HR 0.73, CI 95% 0.60-0.88) compared to parents who had attained primary or lower education.

CONCLUSION

Despite high quality public health care and comprehensive social security, both high parental income and education were associated with lower mortality after childhood cancer. Lower health literacy and financial pressures limiting treatment adherence may explain higher mortality in children with less educated parents and parents with lower income. Motivation and support during treatment and follow-up period is needed concerning the families of these patients.

On Exploring Hidden Structures Behind Cervical Cancer Incidence

Finding new etiological components is of great interest in disease epidemiology. We consider time series version of invariant coordinate selection (tICS) as an exploratory tool in the search of hidden structures in the analysis of population-based registry data. Increasing cancer burden inspired us to consider a case study of age-stratified cervical cancer incidence in Finland between the years 1953 and 2014. The latent components, which we uncover using tICS, show that the etiology of cervical cancer is age dependent. This is in line with recent findings related to the epidemiology of cervical cancer. Furthermore, we are able to explain most of the variation of cervical cancer incidence in different age groups by using only two latent tICS components. The second tICS component, in particular, is interesting since it separates the age groups into three distinct clusters. The factor that separates the three clusters is the median age of menopause occurrence.

Termination of pregnancy and sterilisation in women with childhood-onset type 1 diabetes

AIMS/HYPOTHESIS

The aim of this study was to explore the association between type 1 diabetes and reproductive health indicators in women, focusing on termination of pregnancy and sterilisation.

METHODS

We conducted a registry-based cohort study involving 2281 women with childhood-onset type 1 diabetes, matched for age and birthplace with women without diabetes: two control participants for each woman with diabetes. We compared the frequencies of termination of pregnancy and sterilisation over a 25 year period between women with type 1 diabetes and women without, and estimated standardised incidence ratios (SIRs). Smoothed age and period effects in the incidence of termination of pregnancy or sterilisation were tested statistically.

RESULTS

There were more terminations of pregnancy (SIR 1.67; 95% CI 1.51, 1.86) and sterilisations (SIR 1.69; 95% CI 1.56, 1.83) in women with diabetes than in control women. During recent years, sterilisations in women with diabetes have decreased and the difference compared with control women has vanished. The indications for both procedures showed a statistically highly significant difference: maternal medical indications were almost absent (< 1%) in procedures among control women, but comprised 23.6% of terminations of pregnancy and 22.9% of sterilisations in women with diabetes.

CONCLUSIONS/INTERPRETATION

The indications for termination of pregnancy and sterilisation are different in women with diabetes compared with other women. Pregnancies in women with type 1 diabetes are still terminated more often than in women without diabetes, but the difference in sterilisation rates has disappeared during recent years.

Second primary cancer after major salivary gland carcinoma

BACKGROUND

We investigated the risk of second primary cancers after major salivary gland carcinoma in Finland, with a population of 5.5 million.

METHODS

Nationwide cancer registry data were used to identify patients with major salivary gland carcinoma diagnosed between 1953 and 2014. Standardized incidence ratios (SIRs) were estimated to compare their second primary cancer risk with the respective site-specific cancer risk in the general population.

RESULTS

There were 1727 patients with major salivary gland carcinomas and 222 second primary cancers had been diagnosed in these patients (SIR 1.43). The risk was increased for cancers of the thyroid (SIR 5.12), breast (SIR 1.63), respiratory organs (SIR 1.63), male genital organs (SIR 1.48), melanoma of the skin (SIR 3.35), and nonmelanoma skin cancer (SIR 2.50). The risk was high during the first 5 years and after 20 years of diagnosis.

CONCLUSION

Second primary cancers can occur among patients with major salivary gland carcinoma even after a long time period. This needs to be recognized in the follow-up of these patients.

ACEt: An R Package for Estimating Dynamic Heritability and Comparing Twin Models

Estimating dynamic effects of age on the genetic and environmental variance components in twin studies may contribute to the investigation of gene-environment interactions, and may provide more insights into more accurate and powerful estimation of heritability. Existing parametric models for estimating dynamic variance components suffer from various drawbacks such as limitation of predefined functions. We present ACEt, an R package for fast estimating dynamic variance components and heritability that may change with respect to age or other moderators. Building on the twin models using penalized splines, ACEt provides a unified framework to incorporate a class of ACE models, in which each component can be modeled independently and is not limited by a linear or quadratic function. We demonstrate that ACEt is robust against misspecification of the number of spline knots, and offers a refined resolution of dynamic behavior of the genetic and environmental components and thus a detailed estimation of age-specific heritability. Moreover, we develop resampling methods for testing twin models with different variance functions including splines, log-linearity and constancy, which can be easily employed to verify various model assumptions. We evaluated the type I error rate and statistical power of the proposed hypothesis testing procedures under various scenarios using simulated datasets. Potential numerical issues and computational cost were also assessed through simulations. We applied the ACEt package to a Finnish twin cohort to investigate age-specific heritability of body mass index and height. Our results show that the age-specific variance components of these two traits exhibited substantially different patterns despite of comparable estimates of heritability. In summary, the ACEt R package offers a useful tool for the exploration of age-dependent heritability and model comparison in twin studies.