The completeness of the Swedish Cancer Register: a sample survey for year 1998.

INTRODUCTION: The Swedish Cancer Register (SCR) is used extensively for monitoring cancer incidence and survival and for research purposes. Completeness and reliability of cancer registration are thus of great importance for all types of use of the cancer register. The aim of the study was to estimate the overall coverage of malignant cancer cases in 1998 and to reveal possible reasons behind non-reporting. METHODS: We selected all malignant cancer cases in the Hospital Discharge Register (HDR) from 1998 and compared these records to those reported to the SCR. There were 43,761 discharges for 42,010 individuals of whom 3,429 individuals were not recorded in the SCR. From these 3 429 records we randomly selected 202 patients for review of their medical records to determine whether they should have been registered on the SCR as incident cases in 1998. RESULTS: About half of the 202 cases (93 malignant and 8 benign) should have been reported, which translates into an additional 1 579 malignant cases (95% CI 1 349-1 808), or 3.7% of the cases reported in 1998. The crude incidence rate for males and females combined would increase from 493 per 100,000 to 511 (95% CI 508-514) if these cases were taken into account. CONCLUSION: The overall completeness of the SCR is high and comparable to other high quality registers in Northern Europe. For most uses in epidemiological or public health surveillance, the underreporting will be without major impact. However, for specific research questions our findings have implications, as the degree of underreporting is site specific, increases with age, and does not seem to be random, as diagnoses without histology or cytology verification are overrepresented. An annual comparison of the SCR against the HDR could point to hospitals, geographic areas or specific diagnoses where organizational and administrative changes should be introduced to improve reporting.

Ischemic heart disease mortality among miners and other potentially silica-exposed workers.

BACKGROUND: Some previous studies have observed an increased mortality regarding ischemic heart disease (IHD) among miners and industrial sand workers. The purpose was to study the occurrence of IHD mortality among silica-exposed workers. METHODS: Male miners, well borers, dressing plant workers, and other mine and stone workers were identified in the Swedish National Census of 1970. The total cohort (n = 11,896) was followed from 1970 until December 31, 1995 and linked to the Cause of Death Register. The referent group comprised all gainfully employed men identified in the same census. The Standardized Mortality Ratio was calculated as the ratio between observed and expected numbers of deaths. RESULT: An increased risk due to IHD mortality was observed among miners, well borers, dressing plant workers, and other mine and stone workers. CONCLUSION: These results indicate a possible relation between silica-dust exposure and IHD. The increased risk of IHD mortality is unlikely explained by smoking habits. Shift work might explain some of the increased risk. A low-grade inflammation in the lungs as a result of dust exposure is discussed as a possible cause. However, the key message is that better dose estimates and better confounding control is needed to study the possible relation between silica-dust exposure and IHD.

Testicular cancer incidence in eight northern European countries: secular and recent trends.

OBJECTIVE: Striking geographic variation and marked increasing secular trends characterize the incidence of testicular cancer. However, it is not known whether these patterns have attenuated in recent years and whether they are similar for seminomas and nonseminomas, the two main histologic groups of testicular cancer. METHOD: Cancer registry data, including 27,030 testicular cancer cases, were obtained from Denmark, Estonia, Finland, Latvia, Lithuania, Norway, Poland, and Sweden. Between 57 (Denmark) and 9 (Poland) years of registration were covered. Country-specific temporal trends were estimated, with focus on the last decade and seminomas and nonseminomas. Data from the Nordic countries were further analyzed using an age-period-cohort approach. RESULTS: Age-standardized incidence rates increased annually by 2.6% to 4.9% during the study period, with marginal differences between seminomas and nonseminomas. In the last decade, the increasing trend attenuated only in Denmark (annual change, -0.3%; 95% confidence interval, -1.5 to 0.9). In 1995, the highest and the lowest age-standardized incidence rates (per 10(5)) were 15.2 in Denmark and 2.1 in Lithuania. Incidence rates (i.e., for all cancers and for seminomas and nonseminomas, separately) depended chiefly on birth cohort rather than on calendar period of diagnosis (although both birth cohort and period determined the Danish incidence rates). CONCLUSIONS: Testicular cancer incidence is still increasing, with the exception of Denmark, and a large geographic difference exists. The increasing trend is mainly a birth cohort phenomenon also in recent cohorts. Temporal trends for seminomas and nonseminomas are similar, which suggests that they share important causal factors.

Late mortality among five-year survivors of cancer in childhood and adolescence.

The present study was aimed at assessing differences between the Nordic countries, if any, in late mortality among five-year survivors of childhood cancer. All cases diagnosed before the age of 20 years, between 1960 and 1989, were collected from all Nordic cancer registries. In total, 13,689 patients were identified as five-year survivors and during the extended follow-up 12.3% of them died. Mortality was analysed by decade of diagnosis, for all sites, and for leukaemia, Hodgkin's lymphoma, and central nervous system tumours separately. Analyses were done within a Cox proportional hazards regression framework with adjustments made for gender and age at diagnosis. Hazard ratios were calculated in relation to a weighted Nordic mean based on the proportion of five-year survivors in each country. Overall late mortality was significantly higher in Denmark and Finland than in Norway and Sweden. This could not be explained by inverse differences in five-year survival. The differences diminished over time and had disappeared in the last period. The pattern was similar for both genders. The disappearance of the differences was most probably the effect of a closer collaboration between Nordic paediatric oncologists with development and implementation of common protocols for treatment of childhood cancers in all countries.

Cancer survival in Sweden 1960-1998--developments across four decades.

This paper summarizes a comprehensive study of cancer survival in Sweden from 1960 to 1998. A total of 1021421 persons and 40 different cancer sites were included in the analyses. The main outcome measure is the relative survival rate (RSR) for different sites and follow-up times after diagnosis. The 10-year RSR for all sites combined has increased steadily-from 26.6% among men and 41.8% among women in the 1960s, to 44.6% (men) and 57.6% (women) in the 1990s. The expectation of life for a person diagnosed with cancer today is about 7 years longer than that of one diagnosed during the mid-1960s. About 3 years are gained due to changes in the relative distribution of various cancer types and about 4 years due to improved relative survival. During the 1990s substantial survival improvements were observed not only for uncommon types, such as testicular cancer, Hodgkin's lymphoma and some other haematologic malignancies, but also for cancer of the rectum, kidney and malignant melanoma. Survival for breast and cervical cancer also improved during the 1990s, but not that for pancreatic, liver or lung cancer.

Pleural mesothelioma incidence in Europe: evidence of some deceleration in the increasing trends.

OBJECTIVE: To summarize the geographical and temporal variations in incidence of pleural mesothelioma in Europe, using the extensive data available from European general cancer registries, and consider these in light of recent trends in asbestos extraction, use and import in European countries. MATERIAL AND METHODS: The data were extracted from the European Cancer Incidence and Mortality database (EUROCIM). The inclusion criteria was acceptance in Volume VII of Cancer Incidence in Five Continents. Truncated age-standardized rates per 100,000 for the ages 40-74 were used to summarise recent geographical variations. Standardized rate ratios and 95% confidence intervals for the periods 1986-1990 and 1991-1995 were compared to assess geographical variations in risk. To investigate changes in the magnitude of most recent trends, regression models fitted to the latest available 10-year period (1988-1997) were compared with trends in the previous decade. Fitted rates in younger (40-64) and older adults (65-74) in the most recent period were also compared. RESULTS: There was a great deal of geographical variation in the risk of mesothelioma, annual rates ranging from around 8 per 100,000 in Scotland, England and The Netherlands, to lower than 1 per 100,000 in Spain (0.96), Estonia (0.85), Poland (0.85) and Yugoslavia, Vojvodina (0.56) among men. The rank of the rates for women was similar to that observed for men, although rates were considerably lower. Between 1978 and 1987, rates in men significantly increased in all countries (excepting Denmark). In the following 10 years, there was a deceleration in trend, and a significant increase was detectable only in England and France. In addition, the magnitude of recent trends in younger men was generally lower than those estimated for older men, in both national and regional cancer registry settings. CONCLUSIONS: While mesothelioma incidence rates are still rising in Europe, a deceleration has started in some countries. A decrease may begin in the next few years in certain European populations considering the deceleration of observed trends in mesothelioma and asbestos exposure, as well as the recent ban on its use.

[Cancer in siblings of children with cancer]. / Cancer hos søskende til børn med cancer.

INTRODUCTION: In some rare inherited disorders, such as Li-Fraumeni syndrome, relatives of children with cancer are at increased risk of cancer. We aimed to assess relations between childhood cancer and sibling risk, and evaluate the influence of recessive conditions in cancer causation. MATERIAL AND METHODS: We did a population-based cohort study in the Nordic countries of 42,277 siblings of 25,605 children with cancer. Children with cancer were identified from records in the five Nordic cancer registries, and their siblings from nationwide population registries. Cancers in siblings were documented through record linkage with cancer registries and compared with national incidence rates. We also assessed cancer incidence in parents to identify familial cancer syndromes. RESULTS: 284.2 cancers were expected in siblings, whereas 353 were diagnosed (standardised incidence ratio 1.24 95% CI, 1.12-1.38). Risk ratios for siblings were highest in the first decade of life (2.59; 1.89-3.46). We excluded 56 families with genetic syndromes linked to cancer, which reduced this ratio from 1.7 to 1.0 (0.7-1.3) for siblings younger than 20 years and from 1.3 to 1.0 (0.8-1.3) for those aged 20-29 years. We found no new patterns of familial cancer that indicated inherited susceptibility, or evidence that recessive conditions might contribute to cancers not explained by syndromes. 40% of cancers in siblings that occurred before age 20 years could be attributed to known genetic factors, whereas 60% remained unexplained. DISCUSSION: Apart from rare cancer syndromes, paediatric cancer is not an indicator of increased risk in siblings.