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

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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.