Anthropometric factors and Breslow thickness: prospective data on 2570 cases of cutaneous melanoma in the population-based Janus Cohort.

BACKGROUND: Breslow thickness is the most important prognostic factor of localized cutaneous melanoma (CM), but associations with anthropometric factors have been sparsely and incompletely investigated. OBJECTIVES: To examine prediagnostic body mass index (BMI), body surface area (BSA), and height, weight and weight change in relation to Breslow thickness, overall and by anatomical site and histological subtype; and to assess possible nonlinear associations between these anthropometric factors and Breslow thickness. METHODS: CMs in the Janus Cohort were identified between 1972 and 2014. Linear regression was used to estimate geometric mean ratios (GMRs) of Breslow thickness with 95% confidence intervals (CIs) according to anthropometric factors. Restricted cubic splines in generalized linear models predicted adjusted mean Breslow thickness, and were used to assess possible nonlinear relationships. RESULTS: Of 2570 cases of CM, obese patients had a GMR of 1·16 (95% CI 1·04-1·30) of Breslow thickness vs. normal-weight patients. For BSA and weight, quintile 5 showed GMRs of 1·13 (95% CI 1·00-1·27) and 1·17 (95% CI 1·03-1·33) of Breslow thickness vs. quintile 1, respectively. Associations seemed restricted to superficial spreading melanomas and CMs on the trunk and lower limbs. The associations plateaued at an adjusted mean Breslow thickness of about 2·5 mm (BMI 29 kg m-2 , BSA 2·05 m2 and weight 90 kg), before declining for the highest values. No associations were found for height and weight change. CONCLUSIONS: This large case-series of incident CM demonstrated positive associations between BMI, BSA, weight and Breslow thickness, and suggested that behavioural or other mechanisms apply at high values.

Ultraviolet radiation and skin cancer risk in offshore workers.

BACKGROUND: Excess skin cancer mortality and incidence have been reported among both land-based and offshore petroleum workers. The association between skin cancer and ultraviolet radiation (UVR) exposure has not been examined in these workers, although they have long off-duty periods and high average income that may allow travelling to sunny destinations. In addition, they have access to solariums free of charge on many accommodation platforms. AIMS: To prospectively examine risk of incident cutaneous melanoma (CM) and non-melanoma skin cancer (NMSC), according to sun-tanning habits with adjustment for aromatic hydrocarbon exposure. METHODS: A cohort of men employed offshore from 1965 to 1999 was linked through the Cancer Registry of Norway 1999-2012. Cox regression adapted to a stratified case-cohort design was used to estimate hazard ratios with 95% confidence intervals. RESULTS: The cohort included 24917 men. During 13.5 years of follow-up, 112 CMs and 70 NMSCs occurred. A positive dose-response relationship was seen between sunburn frequency and risk of CM (Ptrend < 0.05) and NMSC (Ptrend < 0.01). Solarium use both before and after age 20 was related to increased risk of NMSC. Sunscreen use was associated with increased risk of NMSC (Ptrend < 0.001). CONCLUSIONS: UVR exposure seems to be a significant contributor to the elevated risk of skin cancer observed in North Sea offshore workers. The positive association between solarium use and NMSC risk adds to the growing body of literature on artificial UV devices as carcinogenic.

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.

Persisting risk of nickel related lung cancer and nasal cancer among Clydach refiners.

OBJECTIVE: To evaluate the risk of lung cancer and nasal cancer among workers employed at the Clydach nickel refinery, South Wales since 1930 by combining data from the two most recently published papers on this cohort. METHODS: Observed and expected numbers of cancer deaths were extracted for workers who had a minimum of five years service and were employed for the first time between 1902 and 1992. Standardised mortality ratios (SMR) were calculated for subgroups according to year of employment, time since first employment, and process work. RESULTS: A persisting excess of respiratory cancer was found for workers employed in the period 1930-92, with a lung cancer SMR of 133 (95% CI 103 to 172) and a SMR for nasal cancer of 870 (95% CI 105 to 3141). The lung cancer excess was most clearly seen 20 years or more after first employment and seemed to be confined to process workers. There was no indication of a further reduction in risk since 1930. CONCLUSION: The extreme nickel related cancer hazard at the refinery before 1920 was greatly reduced during subsequent years. Some of the carcinogenic exposures seem to have remained after 1930, producing an elevated risk of nasal cancer and a 30% excess of lung cancer in the workforce. There was evidence of a persisting risk among process workers first employed since 1953.

Assessment of historical exposures in a nickel refinery in Norway.

OBJECTIVES: The aim of the study was, on the basis of new information on nickel species and exposure levels, to generate a specific exposure matrix for epidemiologic analyses in a cohort of Norwegian nickel-refinery workers with a known excess of respiratory cancer. METHODS: A department-time-exposure matrix was constructed with average exposure to total nickel estimated as the arithmetic mean of personal measurements for periods between 1973 and 1994. From 1972 back to the start of production in 1910, exposure concentrations were estimated through retrograde calculation with multiplication factors developed on the basis of reported changes in the metallurgical process and work environment. The relative distribution of water-soluble nickel salts (sulfates and chlorides), metallic nickel, and particulates with limited solubility (sulfides and oxides) was mainly derived from speciation analyses conducted in the 1990s. RESULTS: The average concentration of nickel in the breathing zone was < or = 0.7 mg/m3 for all workers after 1978. Exposure levels for smelter and roaster day workers were 2-6 mg/m3 before 1970, while workers in nickel electrolysis and electrolyte purification were exposed to concentrations in the range of 0.15-1.2 mg/m3. The level of water-soluble nickel was of the same order for workers in the smelting and roasting departments as in some of the electrolyte purification departments. CONCLUSIONS: Compared with earlier estimates, the present matrix probably offers a more reliable description of past exposures at the plant.

Cohort analysis of cigarette smoking and lung cancer incidence among Norwegian women.

BACKGROUND: Cancer registries have for decades surveyed the development of cancer diseases. Data on incident cases includes demographic variables. Knowledge of the temporal distribution of risk factors on the same variables makes it possible to model the relationship between disease and risk factor. The results of such analyses might be difficult to interpret since they are based on aggregated data. But the availability of these data sources should encourage further exploration of its possibilities and limitations. METHODS: The temporal pattern of smoking habits in 5-year birth cohorts from 1890-1949 was established, with data on the proportions of current smokers, former smokers and non-smokers and estimated average daily consumption of tobacco and average duration of smoking. The lung cancer incidence among the cohorts in 1953-1992 was analysed by a model which included an additive excess risk for smokers that depended on daily dose and duration of smoking. RESULTS: The lung cancer incidence in later decades was adequately described by the model, which showed a simple relationship with smoking behaviour in the cohorts. For both current smokers and former smokers, the excess risk was about proportional to the daily amount smoked and the 4.5 power of duration of smoking. The age-specific rates for non-smokers were close to a fifth-power curve of age. CONCLUSIONS: Even if lung cancer incidence is not determined separately for groups with known smoking habits, plausible estimates of the effect of smoking can be derived if appropriate information is available on temporal smoking habits in the population.

Lung and bladder cancer in a Norwegian municipality with iron and steel producing industry: population based case-control studies.

OBJECTIVES: To investigate the influence of occupation on the rising incidence of lung and bladder cancer among men in a Norwegian municipality where an iron and steel plant constituted the key industry between 1955 and 1989. METHODS: Based on the lung cancer cases reported to the Cancer Registry of Norway from 1980 to 1992 a population based case-control study was performed, including 86 cases and 196 controls. Information on occupations and smoking habits was collected through interviews and from the personnel files from the industrial plants. A case-control study on bladder cancer with 52 cases and 156 controls was carried out to cast light on the role of polycyclic aromatic hydrocarbons (PAHs). RESULTS: An odds ratio (OR) for lung cancer of 2.9 (95% confidence interval (95% CI) 1.2 to 6.7) was associated with exposure to PAHs. Based on data from personnel files, increased risk of lung cancer (OR 2.8 95% CI 1.1 to 7.0) was associated with work experience in the pig iron department at the ironworks. A non-significant OR of 1.8 was associated with exposure to asbestos. Bladder cancer was not associated with exposure to PAHs at the iron, steel, and coke plant, or with experience from any of the production departments at the plant. CONCLUSIONS: One fifth of the lung cancer cases were attributed to exposure to PAHs or asbestos. More than 80% of the cases of lung cancer were attributed to tobacco smoking. The cancer risk in the pig iron department may be due to a combination of exposures to PAH, asbestos, or dust of mixed composition.