TNM stage in the Nordic Cancer Registries 2004-2016: Registration and availability.

BACKGROUND AND PURPOSE: Stage at cancer diagnosis is an important predictor of cancer survival. TNM stage is constructed for anatomic solid cancer diagnoses from tumor size (T), nodal spread (N) and distant metastasis (M) and categorized in groups 0-I, II, II and IV. TNM stage is imperative in cancer diagnosis, management and control, and of high value in cancer surveillance, for example, monitoring of stage distributions. This study yields an overview of TNM availability and trends in stage distribution in the Nordic countries for future use in monitoring and epidemiologic studies. MATERIAL AND METHODS: TNM information was acquired from the cancer registries in Denmark, Norway, Sweden, and Iceland during 2004-2016 for 26 cancer sites in the three former countries and four in Iceland. We studied availability, comparability, and distribution of TNM stage in three periods: 2004-2008, 2009-2013, and 2014-2016, applying a previously validated algorithm of 'N0M0 for NXMX'. For cancers of colon, rectum, lung, breast, and kidney, we examined TNM stage-specific 1-year relative survival to evaluate the quality in registration of TNM between countries. RESULTS: Denmark, Sweden, and Iceland exhibited available TNM stage proportions of 75-95% while proportions were lower in Norway. Proportions increased in Sweden over time but decreased in Denmark. One-year relative survival differed substantially more between TNM stages than between countries emphasizing that TNM stage is an important predictor for survival and that stage recording is performed similarly in the Nordic countries. INTERPRETATION: Assessment and registration of TNM stage is an imperative tool in evaluations of trends in cancer survival between the Nordic countries.

Have the recent advancements in cancer therapy and survival benefitted patients of all age groups across the Nordic countries? NORDCAN survival analyses 2002-2021.

BACKGROUND: Since the early 2000s, overall and site-specific cancer survival have improved substantially in the Nordic countries. We evaluated whether the improvements have been similar across countries, major cancer types, and age groups. MATERIAL AND METHODS: Using population-based data from the five Nordic cancer registries recorded in the NORDCAN database, we included a cohort of 1,525,854 men and 1,378,470 women diagnosed with cancer (except non-melanoma skin cancer) during 2002-2021, and followed for death until 2021. We estimated 5-year relative survival (RS) in 5-year calendar periods, and percentage points (pp) differences in 5-year RS from 2002-2006 until 2017-2021. Separate analyses were performed for eight cancer sites (i.e. colorectum, pancreas, lung, breast, cervix uteri, kidney, prostate, and melanoma of skin). RESULTS: Five-year RS improved across nearly all cancer sites in all countries (except Iceland), with absolute differences across age groups ranging from 1 to 21 pp (all cancer sites), 2 to 20 pp (colorectum), -1 to 36 pp (pancreas), 2 to 28 pp (lung), 0 to 9 pp (breast), -11 to 26 pp (cervix uteri), 2 to 44 pp (kidney), -2 to 23 pp (prostate) and -3 to 30 pp (skin melanoma). The oldest patients (80-89 years) exhibited lower survival across all countries and sites, although with varying improvements over time. INTERPRETATION: Nordic cancer patients have generally experienced substantial improvements in cancer survival during the last two decades, including major cancer sites and age groups. Although survival has improved over time, older patients remain at a lower cancer survival compared to younger patients.

Survival of patients with basal cell carcinoma, squamous cell carcinoma, and squamous cell carcinoma in situ: A whole population study.

BACKGROUND: Keratinocyte carcinoma (KC) is the commonest type of malignancy in humans; however, the impact of KC on survival is poorly understood. OBJECTIVES: This study characterizes the impact of basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and squamous cell carcinoma in situ (SCCis) on the survival of Icelanders. METHODS: This whole population study evaluated relative survival of KC in Iceland by using a cancer registry containing records of all BCC, SCCis, and SCC cases recorded in Iceland between 1981 and 2015. RESULTS: Between 1981 and 2015, 8767 Icelanders were diagnosed with their first localized KC. A total of 6473 individuals with BCC, 1194 with SCCis, and 1100 with invasive SCC, respectively. BCC was not associated with decreased survival except for men diagnosed with BCC between 1981 and 1995 for whom decreased 10-year relative survival was observed (85.3, 95% CI [77.9-92.7]). SCC and SCCis were both associated with a decrease in relative survival for certain population subgroups such as individuals <50 years of age at time of diagnosis. CONCLUSION: Our whole population cohort survival study examining the Icelandic Cancer Registry supports prior studies demonstrating that BCC is not associated with a reduction in relative survival and that SCC and SCCis are associated with comparatively poor relative survival in certain population subgroups.

[Cancer registration in Iceland for 70 years - incidence, mortality and survival].

INTRODUCTION: The Icelandic Cancer Registry (ICR) was founded seventy years ago by the Icelandic Cancer Society. In 2007 the ICR became one of the health registers of the Directorate of Health. In this paper we present cancer incidence, mortality, and survival in Iceland over 70 years. MATERIAL AND METHODS: The ICR receives information on cancer diagnoses from histopathological laboratories, the Hospital Discharge Registry and the Cause of Death Registry. Iceland participates in the Nordic cancer database NORDCAN. Because of the small population size, random variation in numbers is very prominent. Therefore, data from ICR are published as five-year averages. RESULTS: For all malignancies combined, age-standardized incidence (ASI) in men rose steadily until around 15 years ago when a decline started. This is in line with prostate- and lung cancer incidence trends. In women, the ASI was lower than in men, but it is still on the rise despite declining lung cancer incidence. ASI for breast cancer, the most common cancer in women, is increasing. Simultaneously, cancer mortality for both sexes has declined in recent years and cancer survival is improving. CONCLUSIONS: Population-based cancer registration for over 70 years makes it possible to monitor the epidemiology of cancer in Iceland and compare with other countries. The changes in trends in ASI are in line with changes of cancer risk factors and diagnostic policy. The decline in cancer mortality and improvement in survival reflects advances in cancer treatment as well as effects of early detection and prevention.

[Prediction of cancer incidence and prevalence in Iceland up to the year 2040 - Icelandic Cancer Registry and Research Center].

INTRODUCTION: A large increase in new cancer cases is predicted worldwide, due to population growth, ageing and increased cancer risk. The age distribution of the Icelandic population is different from the other Nordic countries. The purpose of this study was to predict the number of new cancer cases in Iceland and other Nordic countries, and cancer survivors in Iceland, up to the year 2040. MATERIALS AND METHODS: Information on cancer diagnoses was retrieved from The Icelandic Cancer Registry and information on population projections from Statistics Iceland. Well known methods for population projection were used to predict the number of new cancer cases in 2040, but adjusted to consider Icelandic circumstances. It is also based on more recent data than is accessible elsewhere. Three different methods were used to estimate the number of survivors in 2040 and are presented here for the first time. RESULTS: In 2040 the predicted yearly average number of new cancer cases in Iceland will be up to 2,903 [95% CI 2.841-2.956], a 57% increase compared with 2022. The increase is higher in Iceland than in other Nordic countries (Norway 41%, Sweden 24%, Denmark 23%, Finland 21%). In 2022, the number of cancer survivors was around 17,500 and is predicted to be between 24,500 and 31,000 in 2040. CONCLUSION: The main reason for the predicted increase of cancer cases and survivors is population trends, especially the ageing of the population. This expected increase in the number of cancer patients and improved survival will increase the demand for healthcare.

Influence of various assumptions for the individual TNM components on the TNM stage using Nordic cancer registry data.

BACKGROUND: The stage at diagnosis is one of the most important predictors for cancer survival. TNM stage is constructed from T (tumor size), N (nodal spread), and M (distant metastasis) components. In many notifications to cancer registries, TNM information is incomplete with unknown N and/or M. We aimed to evaluate the influence of various assumptions for recoding missing N (NX) and M (MX) as N0 and M0 on the proportion with available TNM stage, stage-distribution, and stage-specific relative survival. MATERIAL AND METHODS: We identified 140,201 patients diagnosed with incident cancer of the colon, rectum, lung, breast, or kidney during 2014-2016 in Denmark, Norway, Sweden, or Iceland. Information on TNM were obtained from cancer registry records used for an update of the Nordic cancer statistics database NORDCAN. Patients were followed for death or emigration through 2017. We calculated proportions of available TNM stage, stage distribution, and stage-specific relative survival under different approaches for each cancer site and country. RESULTS: Application of the assumptions yielded higher numbers of cases with available TNM stage for stages 0-I, II, and III. We observed only minor differences in stage-specific one-year relative survival when applying N0M0 for missing N and M, especially for high completeness of TNM registrations, whereas relative survival for remaining cases with missing TNM stage declined substantially. CONCLUSION: We found no major changes in stage-specific one-year relative survival applying N0M0 for NXMX. We conclude that complete TNM information is preferable to making assumptions, but it seems reasonable to consider assuming N0M0 for missing N and M in future studies based on the Nordic cancer registries. An automatic algorithm, though, is not recommended without considering potential area-specific reasons for frequent use of NX and MX. Clinicians should be urged to report complete TNM information to improve surveillance of the TNM stage.

[Breastfeeding in Iceland: Changes in prevalence and duration over a century].

INTRODUCTION: Worldwide, the health-promoting effects of breastfeeding on children and their mothers are indisputable. The frequency and duration of breastfeeding varies greatly internationally but studies on prevalence and influencing factors of breastfeeding in Iceland are scanty and the published ones deal with small groups. The aim of this research is to describe the epidemiology of breastfeeding duration and its influencing factors in Iceland among a large cohort in a whole population over almost one century. MATERIAL AND METHODS: This is a historical cohort study, using data from The Cancer Detection Clinic Cohort of The Icelandic Cancer Society, collected retrospectively by questionnaires during the years 1964-2008. The data consisted of mothers´ reported information on breastfeeding of their 81,889 children, 36,537 first-borns and 45,352 younger siblings. The frequency and duration of breastfeeding was calculated and the effects of the following exposure variables were assessed: Maternal age, BMI (N=4950, data collected 1979-2008) and smoking (N=32.087, data collected 1995-2008), the child's year of birth and its order in the sibling group. RESULTS: The children were born in the period of 1917-2008. In the late 1970s, the average duration of breastfeeding began to increase, in all age groups of mothers, increasing rapidly from 3 months to 7-8 months. At about the same time, the breastfeeding duration increased depending on the birth order of the children, younger children were breastfed for longer than their older siblings. Women with normal weight (BMI 18.5 to 24.9) breastfed their babies the longest, while obese women breastfed the shortest. Women with any history of smoking reported shorter duration of breastfeeding than women who had never smoked. CONCLUSION: The increase in the average duration of breastfeeding in Iceland a few decades ago is in accordance with the information in the World Health Organization's database from European countries 1975-2000, where the Nordic countries and most Northern European countries promoted breastfeeding at a similar time. High BMI and maternal smoking are important variables when studying breastfeeding and this study indicates their negative association with the duration of breastfeeding.

Age-specific survival trends and life-years lost in women with breast cancer 1990-2016: the NORDCAN survival studies.

BACKGROUND: A recent overview of cancer survival trends 1990-2016 in the Nordic countries reported continued improvements in age-standardized breast cancer survival among women. The aim was to estimate age-specific survival trends over calendar time, including life-years lost, to evaluate if improvements have benefited patients across all ages in the Nordic countries. METHODS: Data on breast cancers diagnosed 1990-2016 in Denmark, Finland, Iceland, Norway, and Sweden were obtained from the NORDCAN database. Age-standardized and age-specific relative survival (RS) was estimated using flexible parametric models, as was reference-adjusted crude probabilities of death and life-years lost. RESULTS: Age-standardized period estimates of 5-year RS in women diagnosed with breast cancer ranged from 87% to 90% and 10-year RS from 74% to 85%. Ten-year RS increased with 15-18 percentage points from 1990 to 2016, except in Sweden (+9 percentage points) which had the highest survival in 1990. The largest improvements were observed in Denmark, where a previous survival disadvantage diminished. Most recent 5-year crude probabilities of cancer death ranged from 9% (Finland, Sweden) to 12% (Denmark, Iceland), and life-years lost from 3.3 years (Finland) to 4.6 years (Denmark). Although survival improvements were consistent across different ages, women aged ≥70 years had the lowest RS in all countries. Period estimates of 5-year RS were 94-95% in age 55 years and 84-89% in age 75 years, while 10-year RS were 88-91% in age 55 years and 69-84% in age 75 years. Women aged 40 years lost on average 11.0-13.8 years, while women lost 3.8-6.0 years if aged 55 and 1.9-3.5 years if aged 75 years. CONCLUSIONS: Survival for Nordic women with breast cancer improved from 1990 to 2016 in all age groups, albeit with larger country variation among older women where survival was also lower. Women over 70 years of age have not had the same survival improvement as women of younger age.

[Screening for cancer of the colon and rectum A review on incidence, mortality, cost and benefit].

In this article the incidence and mortality for cancer of the colon and rectum in Iceland is discussed. The two most common screening methods, faecal immunochemical test (FIT) and colonoscopy are compared and an estimate of cost and benefits for the Icelandic society will be made. The incidence of cancer of the colon and rectum has been increasing in Iceland in last decades but mortality has decreased and survival improved. However, more individuals die from cancer of the colon and rectum than from both breast- and cervical cancer added together. It is likely that screening for cancer of the colon and rectum, could prevent at least 6 of the 28 deaths related to those cancers, occurring yearly in Iceland in screening age, given a screening ages of 50-74 years. The extra cost for the Icelandic community due to the implementation of screening for cancer of the colon and rectum will be acceptable due to the lower cost of simpler treatments, lower cancer incidence and reduced mortality.

Cumulative exposure to premenopausal obesity and risk of postmenopausal cancer: A population-based study in Icelandic women.

Obesity, often assessed at one point in time, is an established risk factor of several types of cancer, however, associations with cumulative exposure to obesity across the life course are not well understood. We investigated the relationship between combined measures of duration and intensity of premenopausal overweight and obesity and the incidence of postmenopausal breast, endometrial, and colorectal cancers in Icelandic women. Body mass index (BMI) trajectories between ages 20 and 50 of 88,809 women from the Cancer Detection Clinic Cohort were predicted using growth curve models. Indicators of overweight and obesity duration and intensity were computed and their association with risk of postmenopausal breast, endometrial, and colorectal cancers was examined using multivariate Cox models for subjects followed-up beyond the age of 50 (n = 67,488). During a mean follow-up of 17 years, incident events of 3,016 postmenopausal breast, 410 endometrial and 987 colorectal cancers were ascertained. Each 0.1 kg/m2 per year increase in BMI between ages 20 and 50 was positively associated with risks of postmenopausal breast, endometrium and colorectal cancers with hazard ratios equal to 1.09 (95% Confidence Interval (CI):1.04-1.13), 1.31 (95% CI: 1.18-1.44) and 1.10 (95% CI: 1.00-1.21), respectively. Compared to women who were never obese, cumulative BMI × years of obesity were linearly positively associated with risk of endometrial cancer, whereas the association with breast cancer was initially positive, but leveled off with increasing cumulative BMI × years. Cumulative exposure to obesity may provide additional insights into the etiology of cancer and should be considered in future studies that assess obesity-cancer relationships.

Breast cancer survival in Nordic BRCA2 mutation carriers-unconventional association with oestrogen receptor status.

BACKGROUND: The natural history of breast cancer among BRCA2 carriers has not been clearly established. In a previous study from Iceland, positive ER status was a negative prognostic factor. We sought to identify factors that predicted survival after invasive breast cancer in an expanded cohort of BRCA2 carriers. METHODS: We studied 608 women with invasive breast cancer and a pathogenic BRCA2 mutation (variant) from four Nordic countries. Information on prognostic factors and treatment was retrieved from health records and by analysis of archived tissue specimens. Hazard ratios (HR) were estimated for breast cancer-specific survival using Cox regression. RESULTS: About 77% of cancers were ER-positive, with the highest proportion (83%) in patients under 40 years. ER-positive breast cancers were more likely to be node-positive (59%) than ER-negative cancers (34%) (P < 0.001). The survival analysis included 584 patients. Positive ER status was protective in the first 5 years from diagnosis (multivariate HR = 0.49; 95% CI 0.26-0.93, P = 0.03); thereafter, the effect was adverse (HR = 1.91; 95% CI 1.07-3.39, P = 0.03). The adverse effect of positive ER status was limited to women who did not undergo endocrine treatment (HR = 2.36; 95% CI 1.26-4.44, P = 0.01) and patients with intact ovaries (HR = 1.99; 95% CI 1.11-3.59, P = 0.02). CONCLUSIONS: The adverse effect of a positive ER status in BRCA2 carriers with breast cancer may be contingent on exposure to ovarian hormones.

Trends in cancer survival in the Nordic countries 1990-2016: the NORDCAN survival studies.

BACKGROUND: Differences in cancer survival between the Nordic countries have previously been reported. The aim of this study was to examine whether these differences in outcome remain, based on updated information from five national cancer registers. MATERIALS AND METHODS: The data used for the analysis was from the NORDCAN database focusing on nine common cancers diagnosed 1990-2016 in Denmark, Finland, Iceland, Norway and Sweden with maximum follow-up through 2017. Relative survival (RS) was estimated at 1 and 5 years using flexible parametric RS models, and percentage point differences between the earliest and latest years available were calculated. RESULTS: A consistent improvement in both 1- and 5-year RS was found for most studied sites across all countries. Previously observed differences between the countries have been attenuated. The improvements were particularly pronounced in Denmark that now has cancer survival similar to the other Nordic countries. CONCLUSION: The reasons for the observed improvements in cancer survival are likely multifactorial, including earlier diagnosis, improved treatment options, implementation of national cancer plans, uniform national cancer care guidelines and standardized patient pathways. The previous survival disadvantage in Denmark is no longer present for most sites. Continuous monitoring of cancer survival is of importance to assess the impact of changes in policies and the effectiveness of health care systems.

Nordic Cancer Registries - an overview of their procedures and data comparability.

BACKGROUND: The Nordic Cancer Registries are among the oldest population-based registries in the world, with more than 60 years of complete coverage of what is now a combined population of 26 million. However, despite being the source of a substantial number of studies, there is no published paper comparing the different registries. Therefore, we did a systematic review to identify similarities and dissimilarities of the Nordic Cancer Registries, which could possibly explain some of the differences in cancer incidence rates across these countries. METHODS: We describe and compare here the core characteristics of each of the Nordic Cancer Registries: (i) data sources; (ii) registered disease entities and deviations from IARC multiple cancer coding rules; (iii) variables and related coding systems. Major changes over time are described and discussed. RESULTS: All Nordic Cancer Registries represent a high quality standard in terms of completeness and accuracy of the registered data. CONCLUSIONS: Even though the information in the Nordic Cancer Registries in general can be considered more similar than any other collection of data from five different countries, there are numerous differences in registration routines, classification systems and inclusion of some tumors. These differences are important to be aware of when comparing time trends in the Nordic countries.

Why is colon cancer survival improving by time? A nationwide survival analysis spanning 35 years.

There is limited information present to explain temporal improvements in colon cancer survival. This nationwide study investigates the temporal changes in survival over a 35-year period (1970-2004) in Iceland and uses incidence, mortality, surgery rate, stage distribution, lymph node yield, tumor location and histological type to find explanations for these changes. Patients diagnosed with colon cancer in Iceland 1970-2004 were identified (n = 1962). All histopathology was reassessed. Proportions, age-standardized incidence and mortality, relative, cancer-specific and overall survival and conditional survival were calculated. When comparing first and last diagnostic periods (1970-1978 and 1997-2004), 5-year relative survival improved by 12% for men and 9% for women. At the same time surgery rate increased by 12% and the proportion of stage I increased by 9%. Stage-stratified, improved 5-year relative survival was mainly observed in stages II and III and coincided with higher lymph node yields, proportional reduction of stage II cancers and proportional increase of stage III cancers, indicating stage migration between these stages. Improvement in 1-year survival was mainly observed in stages III and IV. Five-year survival improvement for patients living beyond 1 year was minimum to none. There were no changes in histology that coincided with neither increased incidence nor possibly influencing improved survival. Concluding, as a novel finding, 1-year mortality, which previously has been identified as an important variable in explaining international survival differences, is in this study identified as also being important in explaining temporal improvements in colon cancer survival in Iceland.

Estrogen-progestin use and breast cancer characteristics in lean and overweight postmenopausal women.

PURPOSE: Breast cancer associated with estrogen-progestin (EP) therapy may have more favorable characteristics than cancer in never users, but results are conflicting. It is not well known either whether Body Mass Index (BMI) modifies this association. We investigated breast cancer characteristics in EP users for lean (BMI < 25 kg/m2) and overweight women (BMI ≥ 25 kg/m2). METHODS: The Icelandic Cancer Detection Clinic cohort, with information on breast cancer risk factors for 90% of Icelandic women, was linked with the population-based Icelandic Cancer Registry. A total of 781 women with invasive breast cancer diagnosed 51 years or older were matched with 7761 controls from the cohort. Conditional logistic regression was used for estimating adjusted odds ratios (OR) and 95% confidence intervals (CI) according to tumor characteristics, stratified by BMI. Polytomous logistic regression was applied in a case-only analysis for testing whether the risk associated with EP use differed according to tumor characteristics. RESULTS: Ever EP users had a twofold higher risk of breast cancer compared with never users (OR 2.05, 95% CI 1.71-2.45). In lean women, EP use was significantly less likely to be associated with grade 2 or 3 tumors than grade 1 tumors, contrary to overweight women for whom risk was increased irrespective of grade. EP use in overweight women was associated with a higher risk of lobular than ductal cancer (OR 2.75, 95% CI 1.29-5.87). CONCLUSION: Among lean EP users, tumor characteristics were more favorable than among never users. This effect was not observed for overweight women.

Oestrogen receptor status, treatment and breast cancer prognosis in Icelandic BRCA2 mutation carriers.

BACKGROUND: The impact of an inherited BRCA2 mutation on the prognosis of women with breast cancer has not been well documented. We studied the effects of oestrogen receptor (ER) status, other prognostic factors and treatments on survival in a large cohort of BRCA2 mutation carriers. METHODS: We identified 285 breast cancer patients with a 999del5 BRCA2 mutation and matched them with 570 non-carrier patients. Clinical information was abstracted from patient charts and pathology records and supplemented by evaluation of tumour grade and ER status using archived tissue specimens. Univariate and multivariate hazard ratios (HR) were estimated for breast cancer-specific survival using Cox regression. The effects of various therapies were studied in patients treated from 1980 to 2012. RESULTS: Among mutation carriers, positive ER status was associated with higher risk of death than negative ER status (HR=1.94; 95% CI=1.22-3.07, P=0.005). The reverse association was seen for non-carriers (HR=0.71; 95% CI: 0.51-0.97; P=0.03). CONCLUSIONS: Among BRCA2 carriers, ER-positive status is an adverse prognostic factor. BRCA2 carrier status should be known at the time when treatment decisions are made.

Biliary tract malignancies: a population-based study on incidence, prognosis and management of patients.

BACKGROUND: Biliary tract malignancies are uncommon and few population-based studies are available. METHODS: This nationwide population-based study in Iceland included all patients diagnosed with intra- and extrahepatic cholangiocarcinoma, gallbladder and ampullary cancer from 1984 to 2012. Patients were identified through the Icelandic Cancer Registry. Clinical information was obtained from patient records. RESULTS: Overall 245 patients were identified: 38 had intrahepatic cholangiocarcinoma, 66 extrahepatic cholangiocarcinoma, 73 gallbladder cancer (GBC) and 68 ampullary cancer. Overall incidence for bile tract malignancies was 1-3 per 100,000 person-years and less than 1 by sub-type. The overall bile tract malignancies in males increased from 1.3 (95% CI 0.8-1.8) to 2.5 (1.9-3.1) per 100,000 inhabitants. The incidence of GBC among females decreased from 1.1 (0.7-1.5) to 0.5 (0.2-0.7). Surgery decreased for extrahepatic cholangiocarcinoma (56 to 23%, p = .027), ampullary cancer (80 to 48%, p = .03) and overall bile tract cancer (61 to 32%, p < .0001) but use of chemotherapy increased (4 to 32%, p < .0001). Five-year relative survival rates for men were 15% and 24% for women. No significant improvement was found in survival. CONCLUSIONS: Overall incidence of bile tract malignancies increased in males and GBC decreased in women. Long-term survival is poor and did not improve despite changes in treatment.

Aetiologic heterogeneity in pediatric Hodgkin lymphoma? Evidence from the Nordic countries, 1978-2010.

BACKGROUND: In epidemiological studies, Hodgkin lymphomas (HL) in children younger than 15 years and HL in adolescents and younger adults age 15-35 years has traditionally been studied separately, under the assumption that HL at age 0-14 constitute a homogeneous entity. However, the continued validity of this research practice in affluent settings may be questioned. Specifically, the boundary at age 15 years may not be epidemiologically justified, and therefore also questionable clinically. We therefore updated and further characterised recent HL incidence patterns among Nordic children. MATERIAL AND METHODS: We obtained HL incidence data in children aged 0-14 years for the period 1978-2010 from the five nationwide Nordic cancer registries. The data were analysed by log-linear and/or a mixture of Poisson regression models. RESULTS: The analyses showed statistically significantly decreasing and increasing HL incidence rates in children younger and older than eight years, respectively during the study period. Statistical modelling suggested that cases in children age 0-6 years constituted a disease entity of its own, whereas cases in older children were more likely to belong to the younger adult HL entity. CONCLUSION: Diverging incidence trends and statistical modelling suggest that HL in children age 0-14 years cannot be assumed to constitute a homogeneous disease entity in affluent settings.

Oral contraceptives, hormone replacement therapy and breast cancer risk: a cohort study of 16 928 women 48 years and older.

BACKGROUND: Findings on potential interactive effects of oral contraceptives (OCs) and hormone replacement therapy (HRT) on breast cancer risk have been inconsistent. We aimed to use population-based cohort data to determine whether former use of OCs affects breast cancer risk among HRT users, taking into account regimens of HRT, duration and currency of use. METHODS: The cohort consisted of 16 928 Icelandic women who visited the Icelandic Cancer Detection Clinic in 1979-2006 and provided information on use of OCs and HRT when they were 48 years or older. By record linkage to the Icelandic Cancer Registry, all breast cancer diagnosed during follow-up was identified. Using Cox regression, hazard ratios (HRs) for breast cancer according to hormone use were estimated, adjusting for menstrual and reproductive risk factors. Also, interaction analyses were carried out. RESULTS: Breast cancer risk was significantly increased among ever users of combined estrogen and progestin (EP-HRT) preparations (HR=2.61; 95% CI 2.00-3.41) and not among users of estrogen-only regimens (E-only HRT) (HR=1.13; 95% CI 0.85-1.49). Ever users of both OCs and HRT had higher breast cancer risk than users of only one of the two (HR=2.19; 95% CI 1.67-2.87). After restricting the analysis to EP-HRT and focusing on long-term and current use, there was an indication of a negative interaction with ever OC use (p=0.06); HR=2.87; 95% CI 1.79-4.60 for never OC users and HR=2.24; 95% CI 1.51-3.34 for former OC users. CONCLUSION: After taking HRT regimen, duration and currency of use into account, the results of our population-based cohort study do not support the notion that former OC use increases breast cancer risk among HRT users, on the contrary there was an indication of a slightly lower risk in former OC users, restricted to current, long-term EP-HRT users.

Survival trends for patients diagnosed with cutaneous malignant melanoma in the Nordic countries 1990-2016: The NORDCAN survival studies.

BACKGROUND: The survival in patients diagnosed with cutaneous malignant melanoma (CMM) has improved in the Nordic countries in the last decades. It is of interest to know if these improvements are observed in all ages and for both women and men. METHODS: Patients diagnosed with CMM in the Nordic countries in 1990-2016 were identified in the NORDCAN database. Flexible parametric relative survival models were fitted, except for Iceland where a non-parametric Pohar-Perme approach was used. A range of survival metrics were estimated by sex, both age-standardised and age-specific. RESULTS: The 5-year relative survival improved in all countries, in both women and men and across age. While the improvement was more pronounced in men, women still had a higher survival at the end of the study period. The survival was generally high, with age-standardised estimates of 5-year relative survival towards the end of the study period ranging from 85% in Icelandic men to 95% in Danish women. The age-standardised and reference-adjusted 5-year crude probability of death due to CMM ranged from 5% in Danish and Swedish women to 13% in Icelandic men. CONCLUSION: Although survival following CMM was relatively high in the Nordic countries in 1990, continued improvements in survival were observed throughout the study period in both women and men and across age.