Occupation and cutaneous melanoma: a 45-year historical cohort study of 14·9 million people in five Nordic countries.

BACKGROUND: The age-adjusted incidence of cutaneous melanoma (CM) in the Nordic countries has increased during the last 60 years. Few prospective population-based studies have estimated the occupational variation in CM risk over time. OBJECTIVES: To determine occupational variation in CM risk. METHODS: A historical prospective cohort study with a 45-year follow-up from 1961 to 2005 (Nordic Occupational Cancer Study, NOCCA) based on record linkages between census and cancer registry data for Nordic residents aged 30-64 years in Denmark, Finland, Iceland, Norway and Sweden. National occupational codes were converted to 53 occupational categories, and stratified into indoor, outdoor and mixed work, and into socioeconomic status. The standardized incidence ratios (SIRs) were estimated as observed number of CM cases divided by the expected number calculated from stratum-specific person-years and national CM incidence rates. RESULTS: During a follow-up of 385 million person-years, 83 898 incident cases of CM were identified. In all countries combined, men with outdoor work had a low SIR of 0·79 [95% confidence interval (CI) 0·77-0·81] and men with indoor work had a high SIR of 1·09 (95% CI 1·07-1·11). Differences in women pointed in the same direction. High socioeconomic status was associated with an excess risk: SIR 1·34 (95% CI 1·28-1·40) in men and SIR 1·31 (95% CI 1·26-1·36) in women. Technical, transport, military and public safety workers with potential skin exposure to carcinogens had excess risks. CONCLUSIONS: Occupational variation in CM risk may be partly explained by host, socioeconomic and skin exposure factors. Differences in CM risk across socioeconomic groups attenuated slightly over time.

Incidence and occupational variation of ovarian granulosa cell tumours in Finland, Iceland, Norway and Sweden during 1953-2012: a longitudinal cohort study.

OBJECTIVE: To determine the incidence and occupational variation of granulosa cell tumours (GCTs) in Finland, Iceland, Norway and Sweden over a 60-year period, 1953-2012. DESIGN: A longitudinal cohort study. SETTING AND POPULATION: Finland, Iceland, Norway and Sweden and a total of 249 million women over a 60-year period (1953-2012). The NOCCA (Nordic Occupational Cancer Study) included 6.4 million women with 776 incident GCT cases diagnosed until the end of follow up. METHODS: Incidence rates were calculated from the national cancer registries and compared using quasi-Poisson regression models. Occupation-specific standardised incidence ratios (SIRs) were calculated from the Nordic Occupational Cancer (NOCCA) database. MAIN OUTCOME MEASURES: Incidence rates and standardised incidence ratios. RESULTS: The age-adjusted (World Standard) incidence rates remained quite constant: about 0.6-0.8 per 100 000 for most of the study period. The age-specific incidence was highest at 50-64 years of age. There were no occupations with significantly increased risk of GCT. Major changes in the use of oral contraceptives, postmenopausal hormonal therapy, fertility rate and lifestyle in general during the study period and among different occupational categories do not appear to have a marked effect on the incidence of GCT. CONCLUSION: Our findings support the concept of GCT as a primarily sporadic, not exposure-related, cancer. TWEETABLE ABSTRACT: The Nordic incidence rates of GCTs show stability over time and among different occupational categories.

Benzene exposure and risk of lymphohaematopoietic cancers in 25 000 offshore oil industry workers.

BACKGROUND: The aim of this work was to examine the risk of lymphohaematopoietic (LH) cancer according to benzene exposure among offshore workers. METHODS: Cancer registry data were used to identify 112 cancer cases diagnosed during 1999-2011 in a cohort of 24 917 Norwegian men reporting offshore work between 1965 and 1999. Analyses were conducted according to a stratified case-cohort design with a reference subcohort of 1661 workers. Cox regression was used to estimate hazard ratios with 95% confidence intervals, adjusted for other benzene exposure and smoking. RESULTS: Most workers were exposed to benzene for <15 years. The upper range values of average intensity and cumulative exposure were estimated to 0.040 p.p.m. and 0.948 p.p.m.-years, respectively. Risks were consistently elevated among exposed workers for all LH cancers combined and for most subgroups, although case numbers were small and yielded imprecise risk estimates. There was evidence of dose-related risk patterns according to cumulative exposure for acute myeloid leukaemia (AML), multiple myeloma (MM) (P trends 0.052 and 0.024, respectively), and suggestively so for chronic lymphocytic leukaemia (CLL) according to average intensity (P trend 0.094). CONCLUSIONS: Our results support an association between cumulative and intensity metrics of low-level benzene exposure and risk for AML, MM, and suggestively for CLL.

Cancer incidence among 41,000 offshore oil industry workers.

BACKGROUND: Cancer incidence among Norwegian offshore oil industry workers has been studied in two equally sized cohorts of 28000 workers, in a survey-based cohort study followed 1999-2005 and a register-based cohort study followed 1981-2003. AIMS: To determine the overall cancer incidence in both cohorts merged, with an extended follow-up. METHODS: The merged cohort yielded 41,140 individuals followed for cancer diagnoses 1999-2009. Standardized incidence ratios (SIRs) with 95% confidence intervals (CIs) were computed by gender and by period of first employment using cancer registry data. RESULTS: Among female workers, the total number of cancers was slightly higher than expected (SIR 1.17, 95% CI 1.02-1.34), and excesses of acute myeloid leukaemia (AML) (SIR 5.29, 95% CI 1.72-12), malignant melanoma (SIR 2.13, 95% CI 1.41-3.08) and lung cancer (SIR 1.69, 95% CI 1.03-2.61) were observed. Among male workers, the total number of cancer cases was close to that expected (SIR 1.03, 95% CI 0.99-1.08), but cases of pleural cancer (SIR 2.56, 95% CI 1.58-3.91) and bladder cancer (SIR 1.25, 95% CI 1.05-1.49) were higher than expected. Among male workers first employed before 1986, the numbers of observed cancer cases were higher than expected for most sites, while this was not evident among those employed later. CONCLUSIONS: Further studies with exposure data and confounder control are needed to address whether the observed excesses of pleural cancer and AML can be attributed to offshore work.

Occupation and risk of primary fallopian tube carcinoma in Nordic countries.

The aetiology of primary Fallopian tube carcinoma (PFTC) is poorly understood. Occupational exposures may contribute to PFTC risk. We studied incidence of PFTC in occupational categories in the Nordic female population aged 30-64 years during the 1960, 1970, 1980/1981 and/or 1990 censuses in Denmark, Finland, Iceland, Norway and Sweden. Standardized incidence ratios (SIRs) for the years following inclusion in the study up to 2005 were calculated for 53 occupations; the expected numbers of cases were based on PFTC incidence in the national populations. Altogether 2,206 PFTC cases were detected during follow up via data linkages with the Nordic cancer registries. Significantly increased risks of PFTC were observed for smelting workers (SIR 3.99, 95% confidence interval 1.46-8.68, Obs = 6), artistic workers (2.64, 1.44-4.43, Obs = 14), hairdressers (2.18, 1.41-3.22, Obs = 25), packers (1.62, 1.11-2.29, Obs = 32), nurses (1.49, 1.14-1.92, Obs = 60), shop workers (1.25, 1.07-1.46, Obs = 159) and clerical workers (1.20, 1.07-1.35, Obs = 271) and these sustained over times and different Nordic countries. There was a nonsignificant increased risk for PFTC among welders, printers, painters and chemical process workers. The risk was significantly and consistently low for women working in farming (0.68, 0.47-0.95, Obs = 34) and among economically inactive women (0.88, 0.82-0.94, Obs = 833). The possible role of occupational exposures to the PFTC risks found in this study must be further evaluated in studies with a possibility to adjust for possible confounding factors, such as reproductive and life-style factors, which was not possible in our study.

Role of medical history and medication use in the aetiology of upper aerodigestive tract cancers in Europe: the ARCAGE study.

BACKGROUND: The study aimed to investigate the role of medical history (skin warts, Candida albicans, herpetic lesions, heartburn, regurgitation) and medication use (for heartburn; for regurgitation; aspirin) in the aetiology of upper aerodigestive tract (UADT) cancer. METHODS: A multicentre (10 European countries) case-control study [Alcohol-Related CAncers and GEnetic susceptibility (ARCAGE) project]. RESULTS: There were 1779 cases of UADT cancer and 1993 controls. History of warts or C. albicans infection was associated with a reduced risk [odds ratio (OR) 0.80, 95% confidence interval (CI) 0.68-0.94 and OR 0.73, 95% CI 0.60-0.89, respectively] but there was no association with herpetic lesions, heartburn, regurgitation or medication for related symptoms. Regurgitation was associated with an increased risk for cancer of the oesophagus (OR 1.47, 95% CI 0.98-2.21). Regular aspirin use was not associated with risk of UADT cancer overall but was associated with a reduced risk for cancer of oesophagus (OR 0.51, 95% CI 0.28-0.96), hypopharynx (OR 0.53, 95% CI 0.28-1.02) and larynx (OR 0.74, 95% CI 0.54-1.01). CONCLUSIONS: A history of some infections appears to be a marker for decreased risk of UADT cancer. The role of medical history and medication use varied by UADT subsites with aspirin use associated with a decreased risk of oesophageal cancer and suggestive of a decreased risk of hypopharyngeal and laryngeal cancers.

Life course social mobility and risk of upper aerodigestive tract cancer in men.

The aim of this study was to explore associations between social mobility and tumours of the upper aero-digestive tract (UADT), focussing on life-course transitions in social prestige (SP) based on occupational history. 1,796 cases diagnosed between 1993 and 2005 in ten European countries were compared with 1585 controls. SP was classified by the Standard International Occupational Prestige Scale (SIOPS) based on job histories. SIOPS was categorised in high (H), medium (M) and low (L). Time weighted average achieved and transitions between SP with nine trajectories: H --> H, H --> M, H --> L, M --> H, M --> M, M --> L, L --> H, L --> M and L --> L were analysed. Odds ratios (ORs) and 95%-confidence intervals [95%-CIs] were estimated with logistic regression models including age, consumption of fruits/vegetables, study centre, smoking and alcohol consumption. The adjusted OR for the lowest versus the highest of three categories (time weighted average of SP) was 1.28 [1.04-1.56]. The distance of SP widened between cases and controls during working life. The downward trajectory H --> L gave an OR of 1.71 [0.75-3.87] as compared to H --> H. Subjects with M --> M and L --> L trajectories ORs were also elevated relative to subjects with H --> H trajectories. The association between SP and UADT is not fully explained by confounding factors. Downward social trajectory during the life course may be an independent risk factor for UADT cancers.

Eighth international mesothelioma interest group.

The eighth International Mesothelioma Interest Group (IMIG) meeting was held in Chicago, IL, United States, in 19-22 October 2006 to discuss mesothelioma - the cancer often linked to asbestos exposure. It is a very aggressive malignancy with a median survival of less than 1 year from diagnosis. Millions of people have been exposed worldwide to asbestos, especially during the second half of the twentieth century when asbestos use increased significantly. The tons of asbestos utilized in the past remain a health hazard for current and future generations because asbestos is difficult to be disposed off. This makes asbestos and mesothelioma research a public health issue in addition to a medical problem. Moreover, the very high costs of asbestos litigation have a significant impact on the whole economy. In the United States, up until 2001, defendant companies had paid 54 billion dollars in claims and estimated future liabilities ranged from 145 to 210 billion. Therefore, asbestos research is of great interest to a large audience that includes patients, millions of asbestos-exposed individuals, scientists, physicians, public health officials, politicians, unions of asbestos workers, lawyers and the public at large. During the past few years, there has been significant progress in understanding the process of mineral fiber carcinogenesis and mesothelioma pathogenesis. With improved understanding of the pathogenesis of mesothelioma, new diagnostic, preventive and therapeutic options are being developed. A total of 247 papers were presented at the IMIG: the abstracts of these presentations were published in Lung Cancer, Supplement 1, October 2006. Here, experts in different disciplines critically review some of the most exciting presentations of the IMIG meeting. The result is a comprehensive review of the research field of asbestos carcinogenesis and mesothelioma, and of the progress that has been made in recent years in both basic and clinical sciences.

Predictors of oropharyngeal cancer survival in Europe.

OBJECTIVES: HPV16-positive oropharyngeal cancer (OPC) patients experience better outcomes compared to HPV16-negative patients. Currently, strategies for treatment de-escalation are based on HPV status, smoking history and disease stage. However, the appropriate cut-point for smoking and the role of other non-clinical factors in OPC survival remains uncertain. MATERIALS AND METHODS: We examined factors associated with OPC outcome in 321 patients recruited in a large European multi-center study. Seropositivity for HPV16 E6 was used as a marker of HPV16 positive cancer. Hazard ratios (HR) and confidence intervals (CI) were estimated using Cox proportional models adjusted for potential confounders. RESULTS: Overall 5-year survival following OPC diagnosis was 50%. HPV16-positive OPC cases were at significantly lower risk of death (aHR = 0.51, 95% CI: 0.32-0.80). A significant effect on OPC survival was apparent for female sex (aHR 0.50: 95% CI: 0.29-0.85) and being underweight at diagnosis (aHR: 2.41, 95% CI: 1.38-4.21). A 10 pack year smoking history was not associated with overall survival. Higher stage at diagnosis appeared as the only factor significantly associated with OPC recurrence (aHR: 4.88, 95% CI: 2.12-11.21). CONCLUSION: This study confirms that HPV16 status is an independent prognostic factor for OPC survival while female sex lowers risk of death and being underweight at diagnosis increases the risk of death. Smoking was not an independent predictor of OPC survival.

Expression of matrix metalloproteinase-2 in serous borderline ovarian tumors is associated with noninvasive implant formation.

OBJECTIVE: To investigate matrix metalloproteinase (MMP) proteolytic and vascular endothelial growth factor (VEGF) and receptor (VEGFR-1, VEGFR-2) angiogenetic capacity in serous borderline ovarian tumors (S-BOTs) for women with and without noninvasive implants. METHODS: The population was made up of 99 patients with S-BOTs as the primary diagnosis between 1985 and 1995, 44 of whom had noninvasive implants and 55 without implants. MMP-2, MMP-14, the type-2 tissue inhibitor of MMPs (TIMP-2), and VEGF and receptors (VEGFR-1, VEGFR-2) were examined by immunhistochemistry. RESULTS: Strong positive (+++) MMP-2 staining was found more frequently in women with primary S-BOTs and noninvasive implants (76%) than in those without implants (53%; p < 0.05). In contrast, staining for MMP-14 and TIMP-2 was not significantly different in the two groups. Furthermore, expression of MMP-2, MMP-14, and TIMP-2 was similar in primary tumors and in their noninvasive implants. Most tumors in both groups had no VEGF expression (84% in the noninvasive implant group and 82% in the group without implants), while moderate (++) to strong (+++) expression of VEGFR-1 and VEGFR-2 was detected in 79% and 94% of the two tumor groups, with no significant difference between the groups. CONCLUSIONS: Enhanced MMP-2 was seen in primary S-BOT with noninvasive implants. The presence of noninvasive implants was prognostic for disease-free survival.

Mortality from non-malignant diseases in a cohort of female pulp and paper workers in Norway.

OBJECTIVES: The objective of the present study was to investigate the risk of death from non-malignant diseases in female pulp and paper workers in Norway. METHODS: A total of 3143 women first employed between 1920-93 were included in the study cohort. Information about each cohort member was obtained from personnel record files in the mills in order to identify employment periods and job categories. Data on cause and date of death were added by linkage to the Cause of Death Register using unique personal identification numbers. The follow up period was 1951-2000. Standardised mortality ratios (SMRs) with 95% confidence intervals (95% CIs) were calculated using the national female mortality rates as reference. Poisson regression analysis was used to examine internal relations between the duration of employment in paper departments and the risk of death from selected causes. Relative risks (RRs) and 95% CIs were calculated. RESULTS: The study showed a significantly increased risk for total non-malignant mortality (SMR = 1.14, 95% CI 1.05 to 1.24), mainly due to increased mortality from ischaemic heart disease (SMR = 1.22, 95% CI 1.03 to 1.43) and cerebrovascular diseases (SMR = 1.16, 95% CI 0.94 to 1.42). Analysis by department showed the highest risk of death in paper department workers with short term employment. Internal analyses showed a 5% and 9% increase in risk of dying from ischaemic heart disease and respiratory diseases, respectively, among paper department workers exposed to paper dust. The risk decreased with increasing duration of employment. CONCLUSION: The increased risk of ischaemic heart diseases and respiratory diseases seen among employees of paper departments may be related to exposure to paper dust.

Cross shift changes in lung function among bar and restaurant workers before and after implementation of a smoking ban.

OBJECTIVE: To study possible cross shift effects of environmental tobacco smoke (ETS) on pulmonary function among bar and restaurant employees before and after the implementation of a smoking ban in Norway. METHODS: The study included 93 subjects employed in 13 different establishments in Oslo. They were examined at the beginning and end of a workshift both while ETS exposure was present and when smoking was banned. The mean exposure level of nicotine and total dust before the ban was 28 microg/m3 (range 3-65) and 275 microg/m3 (range 81-506), respectively. Following the smoking ban, the mean level of nicotine and total dust was 0.6 mug/m3 and 77 microg/m3, respectively. Assessment of lung function included dynamic lung volumes and flows. RESULTS: The cross shift reduction in forced vital capacity (FVC) among 69 subjects participating in both examinations changed from 81 ml (SD 136) during exposure to ETS to 52 ml (SD 156) (p = 0.24) following the smoking ban. The reduction in forced expired volume in one second (FEV1) during a workshift, was borderline significantly reduced when comparing the situation before and after the intervention, by 89 ml (SD = 132) compared to 46 ml (SD = 152) (p = 0.09), respectively. The reduction in forced mid-expiratory flow rate (FEF25-75%) changed significantly from 199 ml/s (SD = 372) to 64 ml/s (SD = 307) (p = 0.01). Among 26 non-smokers and 11 asthmatics, the reduction in FEV1 and FEF25-75% was significantly larger during ETS exposure compared to after the smoking ban. There was an association between the dust concentration and decrease in FEF25-75% before the ban among non-smokers (p = 0.048). CONCLUSIONS: This first study of cross shift changes before and after the implementation of a smoking ban in restaurants and bars shows a larger cross shift decrease in lung function before compared with after the implementation of the ban.

Symptoms and referral of women with epithelial ovarian tumors.

OBJECTIVE: To study referral to hospital units and the clinical characteristics of women with epithelial ovarian tumors in a prospective, population-based study. METHODS: Clinical information on all women diagnosed with epithelial invasive (n=486) and borderline ovarian tumors (n=137) in Norway during 2002 was derived from notifications to the Cancer Registry of Norway and medical, surgical and histopathological records. RESULTS: Sixty-one percent of women with invasive ovarian tumors were initially referred to gynecology units. The 38% of women referred to surgical and medical units were more likely to have symptoms as 'bowel irregularity', 'pain outside the abdominal cavity', 'persisting fatigue' and 'respiratory difficulties'. These women were older, had lower performance status and had a delay in treatment of 20 and 24 days respectively compared to 11 at gynecology units. CONCLUSION: Greater awareness of the symptoms of ovarian cancer might lead to earlier diagnosis and treatment and thus possibly improve survival.

Alcohol abstainers: a low-risk group for cancer--a cohort study of Norwegian teetotalers.

Groups with assumed health-protective life-styles have been studied for several decades, in search of causes for cancer. We have analyzed cancer incidence, total mortality, and cause-specific mortality in Norwegian teetotalers to assess the possible health gains from an alcohol-abstaining life-style. A cohort of 5332 members of the International Organization of Good Templars was followed for 10 years from 1980. The cancer incidence and the cause-specific mortality of the cohort has been compared to that of the total Norwegian population. The standardized incidence ratio (SIR) for all cancer sites was 74 [95% confidence interval (CI), 64-80] for men and 72 (95% CI, 61-84) for women. For possible alcohol-associated cancers, such as cancer of the oral cavity, pharynx, esophagus, liver, and larynx, the SIR was 43 (95% CI, 17-88) for both sexes combined. For lung cancer the SIR was 57 (95% CI, 37-90) for men and 10 (95% CI, 0-57) for women. When all alcohol- and tobacco-associated cancers were excluded, the SIR for both sexes combined was 79 (95% CI, 69-87). The standardized mortality ratio for total mortality was 81 (95% CI, 65-74). This significant decrease in total mortality was caused by reduced risks for all major causes of death. The study indicates that members of the Norwegian chapter of the International Organization of Good Templars are a low-risk group not only regarding alcohol- and tobacco-associated cancers, but also regarding all other cancers.

Occupational cancer research in the Nordic countries.

Occupational cancer research in the Nordic countries benefits from certain structural advantages, including the existence of computerized population registries, national cancer registries with high-quality data on cancer incidence, and a personal identification number for each inhabitant. This article outlines the utilization of this research infrastructure in Denmark, Finland, Iceland, Norway, and Sweden, together with research examples from the different countries. Future research on occupational cancer in this region requires that national legislation on electronic handling of sensitive personal information should not be stricter than the European Union Directive on individual protection with regard to personal data. A personal identification number is essential both for keeping up the high quality of data of the registers and for the high quality of the process of linking the different data sources together. Although previous occupational research has focused on male workers, a broader approach is needed in the future, including a study of how cancer risk in women may be affected by occupational activity and the question of possible cancer risk in offspring of men and women exposed to workplace carcinogens.

Occupational cancer in central European countries.

The countries of central Europe, including Poland, the Czech Republic, Slovakia, Hungary, Romania, and Bulgaria, suffer from environmental and occupational health problems created during the political system in place until the late 1980s. This situation is reflected by data on workplace exposure to hazardous agents. Such data have been systematically collected in Skovakia and the Czech Republic since 1977. The data presented describe mainly the situation in the early 1990s. The number of workers exposed to risk factors at the workplace represent about 10% of the working population in Slovakia and 30% in Poland. In Slovakia in 1992 the percentage of persons exposed to chemical substances was 16.4%, to ionizing radiation 4.3%, and to carcinogens 3.3% of all workers exposed to risk factors. The total number of persons exposed to substances proven to be carcinogens in Poland was 1.3% of the employees; 2.2% were exposed to the suspected carcinogens. The incidence of all certified occupational diseases in the Slovak Republic was 53 per 100,000 insured employees in 1992. Cancers certified as occupational cancers are skin cancer caused by occupational exposure to carcinogens, lung cancer caused by ionizing radiation, and asbestosis together with lung cancer. Specific information on occupational cancers from Romania and Bulgaria was not available for this paper. It is difficult to predict a trend for future incidences of occupational cancer. Improved control technology, governmental regulatory activity to reduce exposure, surveillance of diseases and risk factors, and vigilant use of preventive measures should, however, ultimately reduce occupational cancer.

Cancer risk among female nurses: a literature review.

Some studies have demonstrated increased risk of different cancers among female nurses. A review of relevant papers was made to assess whether the increase is caused by occupational exposures or other factors. A computerized literature search on combinations of the keywords 'nurses', 'occupation', 'hazards', 'cancer' and 'mortality' and related articles was performed. A total of 30 reports were identified from 19 independent studies conducted between 1983 and 2001. The majority of the studies were registry studies, with limited data on employment history and confounding factors. In conclusion, knowledge about exposures and observed excesses of cancer risk give reason to suspect an occupational influence on breast cancer and leukaemia. The grouping together of nurses from different workplaces may camouflage real differences in risk. Future studies should collect information at the individual level about work history and personal risk factors.

Heavy drinking in the restaurant business: the role of social modelling and structural factors of the work-place.

The role of social modelling and structural factors of the work-place in predicting the probability of heavy drinking was investigated in a sample of 3267 Norwegian male and female waiters and cooks. In the logistic regression analysis, the probability of heavy drinking was increased by two social modelling factors and one structural factor. Having co-workers who, at least weekly, took an end-of-work drink at the work-place gave an odds ratio for heavy drinking of 2.8 (95% CI 1.9-4.1), and having co-workers who went out after work at least every week gave an odds ratio of 1.8 (95% CI 1.2-2.8). Working at a place with a liberal alcohol policy gave an odds ratio 1.5 (95% CI 1.1-2.2). Among the background factors, only household type significantly predicted heavy drinking. As compared with living with children, the odds for heavy drinking when living alone was 4.3 (95% CI 2.9-6.4). The results indicate that preventive measures in the restaurant business should not only concentrate on the individual, but also deal with factors related to the occupational activity that promote and sustain heavy drinking.

Work-related cancer in the Nordic countries.

This report presents 20 years' of cancer incidence data by occupational group for the Nordic populations. The study covers the 10 million people aged 25-64 years at the time of the 1970 censuses in Denmark, Finland, Norway, and Sweden, and the 1 million incident cancer cases diagnosed among these people during the subsequent 20 years. The project was undertaken as a cohort study with linkage of individual records based on the personal identification numbers used in all the Nordic countries. In the 1970 censuses, information on occupation for each economically active member of the household was provided in free text in self-administered questionnaires. The data were centrally coded and computerized in the statistical offices. Norway, Sweden, and Finland used the Nordic Classification of Occupations, while Denmark used a national coding scheme. However, all the data could be reclassified into 53 occupational groups and 1 group of economically inactive persons. Person-years at risk were accumulated from 1 January 1971 until the date of emigration, date of death or 31 December 1987 in Denmark, 1989 in Sweden, 1990 in Finland, and 1991 in Norway. The 4 countries all had nationwide registration of incident cancer cases during the entire study period. All incident cancer cases during the individual risk periods were included in the analysis. Despite minor differences between the countries, the International Classification of Diseases, 7th revision, formed the core basis for the diagnostic coding in all 4 countries. For the present study the incident cancer cases have been classified into 35 broad diagnostic groups. The observed number of cancer cases in each group of persons defined by country, gender, and occupation was compared with the expected number calculated from the age-, gender-, and period-specific person-years and the incidence rates for the national population. The result has been presented as a standardized incidence ratio (SIR), defined as the observed number of cases divided by the expected number and multiplied by 100. In the tables of this report, all the SIR values for which the upper limit of the 95% confidence interval is below 100 are printed in green and all those for which the lower limit of the confidence interval is above 100 are printed in red. For all cancers combined, the study showed a wide variation among the men, from an SIR of 79 for farmers to 159 for waiters. The occupations with the highest SIR values also included seamen and workers producing beverages and tobacco. Among the women the SIR values varied from 83 for gardeners to 129 for tobacco workers. Low SIR values were found for farmers and teachers. Outdoor workers such as fishermen and gardeners had the highest risk of lip cancer, while the lowest risk was found among indoor workers such as physicians and artistic workers. Almost all pleural cancers are associated with asbestos exposure. Accordingly, plumbers, welders, mechanics, and seamen were the occupations with the highest risk. There was also an excess risk of pleural cancer in the occupational group of technical, chemical, physical, and biological workers, including, among others, engineers and chemists potentially exposed to asbestos. The wood workers included in the present study had the highest risk of nasal cancer. Most studies of nasal cancer have shown increased risks associated with exposure to wood dust, both for those in furniture making and for those exposed exclusively to soft wood. Nickel refinery workers are also known for their high risk of nasal cancer. In the present study they were included in the occupational group of smelting workers. Lung cancer was the most frequent cancer among men in the present study. Tobacco smoking is the major risk factor for this disease, but occupational exposures also play an important role. Waiters and tobacco workers had the highest risk of lung cancer. Miners and quarry workers also had a high risk of lung cancer, which may be related to