Occupational risk factors for non-Hodgkin's lymphoma: a population-based case-control study in Northern Germany

OBJECTIVES: To identify occupational factors associated with non-Hodgkin's lymphoma (NHL). METHODS: A population-based case-control study was conducted in which incident cases of high-malignancy NHL (NHL(high)), low-malignancy NHL (NHL(low)), and chronic lymphocytic leukemia (CLL) were ascertained during the period 1986-1998 among men and women aged 15-75 years residing in six German counties; controls were drawn from population registries. Occupational histories were collected and agent-specific exposures were estimated via a job-exposure-matrix. Odds ratios were estimated by conditional logistic regression. RESULTS: A total of 858 cases were included in these analyses. Agricultural workers [odds ratio (OR) = 2.67, 95% confidence interval (CI): 0.99, 7.21) and farmers (OR = 1.98, 95% CI: 0.98, 3.98] had elevated risk of NHL(high). Risk of NHL(low) was elevated among agricultural workers (OR = 2.46, 95% CI: 1.17, 5.16), and among blacksmiths, toolmakers, and machine tool operators (OR = 3.12, 95% CI: 1.31, 7.47). Workers in sales and construction had elevated risks of NHL(high) and NHL(low). Exposure to arsenic compounds, chlorophenols, diesel fuel, herbicides, nitrites/nitrates/nitrosamines, and organic dusts were associated with NHL(high) and NHL(low), while exhibiting little association with CLL. A positive monotonic trend in NHL(low) risk across tertiles of cumulative diesel fuel exposure was observed [P-value for test of linear trend (P) = 0.03]. CONCLUSIONS: These findings provide insights into several potential occupational risk factors for NHL and suggest some specific occupational agents for further investigation.     

Brain tumours and exposure to pesticides: a case-control study in southwestern France

Background

Brain tumours are often disabling and rapidly lethal; their aetiology is largely unknown. Among potential risk factors, pesticides are suspected.

Objective

To examine the relationship between exposure to pesticides and brain tumours in adults in a population‐based case–control study in southwestern France.

Methods

Between May 1999 and April 2001, 221 incident cases of brain tumours and 442 individually matched controls selected from the general population were enrolled. Histories of occupational and environmental exposures, medical and lifestyle information were collected. A cumulative index of occupational exposure to pesticides was created, based on expert review of lifelong jobs and tasks. Separate analyses were performed for gliomas and meningiomas.

Results

A non‐statistically significant increase in risk was found for brain tumours when all types of occupational exposure to pesticides were considered (OR = 1.29, 95% CI 0.87 to 1.91) and slightly higher but still non‐statistically significant when gliomas were considered separately (OR = 1.47, 95% CI 0.81 to 2.66). In the highest quartile of the cumulative index, a significant association was found for brain tumours (OR = 2.16, 95% CI 1.10 to 4.23) and for gliomas (OR = 3.21, 95% CI 1.13 to 9.11), but not for meningiomas. A significant increase in risk was also seen for the treatment of home plants (OR = 2.24, 95% CI 1.16 to 4.30) owing to environmental exposure to pesticides.

Conclusions

These data suggest that a high level of occupational exposure to pesticides might be associated with an excess risk of brain tumours, and especially of gliomas.     

Occupation and smoking as risk factors for lung cancer: a population-based case-control study

BACKGROUND: Lung cancer is associated with occupation, but not much is known about the influence exerted on risk by length of exposure and the joint effect of occupational exposure and tobacco on risk of lung cancer. METHODS: Through a population-based case-control study, we defined risk professions as those that have been associated previously with higher risk of lung cancer. RESULTS: The relative risk seems to increase linearly and significantly with the number of years spent in risk occupations, rising significantly by 28% for every 10 years in a risk profession. Should such occupations be combined with exposure to a smoking habit, then in the case of heavy smokers, a working career spanning 20 years or more in risk occupations would mean tripling the possibility of developing lung cancer from occupation. CONCLUSIONS: The high risks observed indicate a public health problem and indicate that joint exposure to risk professions and tobacco ought to be avoided. We must stress from these results the need for effective education for all workers.     

Bladder cancer and occupation: a report from the Belgian case-control study on bladder cancer risk

BACKGROUND: The aim of this study was to add to the data on associations between occupation and bladder cancer thereby strengthening the case for focused research on specific occupational categories. METHODS: Two hundred two cases and 390 controls participated in this population-based case-control study. Age, sex, smoking, and education adjusted odds ratios (ORs) were calculated for each occupation by unconditional logistic regression. RESULTS: The occupational group of domestic helpers, cleaners, and launderers exhibited a significantly elevated risk of bladder cancer. Elevated non-significant risks (OR > 1.5) were observed for painters and varnishers, electronic equipment assemblers, general laborers, building finishers, carpenters and joiners, architects and engineers, and textile and garment workers. CONCLUSIONS: This study suggests that domestic helpers, cleaners, and launderers probably experience an increased risk of bladder cancer. Although no other occupations showed significantly increased risks, the non-significantly elevated risks for painters, carpenters, and textile workers could be confirmed by results from earlier studies.     

Registry-based case-control study of cancer in California firefighters

BACKGROUND: There is no consensus whether firefighters are at increased cancer risk for particular cancers. Previous studies have been small, mostly investigated cancer mortality, and suggested increased risks for brain, bladder, testicular, prostate, thyroid and colo-rectal cancers, leukemia, and melanoma. METHODS: Records of all male cancers registered in California during 1988-2003 were obtained. Firefighters were identified from occupation and industry text fields. Logistic regression analysis used other cancers as controls. RESULTS: Of the 804,000 eligible records, 3,659 had firefighting as their occupation. Firefighting was associated with testicular cancer (odds ratio = 1.54, 95% confidence interval: 1.18-2.02), melanoma (1.50, 1.33-1.70), brain cancer (1.35, 1.06-1.72), esophageal cancer (1.48, 1.14-1.91), and prostate cancer (1.22, 1.12-1.33). CONCLUSIONS: Use of other-cancer controls and lack of an occupational history may have biased relative risks towards the null. However, this study, which contained more firefighter cancers than any previous epidemiologic study, produced evidence supporting some prior hypotheses.     

体力活动与女性乳腺癌发病关系的病例对照研究

目的 探讨体力活动与乳腺癌发病的关系。方法 采用以医院为基础的病例对照研究,调查某大学2所附属医院2012年4月~2014年12月间确诊的25～70岁549例乳腺癌患者和同期同医院就诊的549例非肿瘤患者的体力活动情况和相关危险因素。采用非条件Logistic回归模型分析体力活动与乳腺癌发病的关系。结果 校正各种混杂因素后,非职业性体力活动与乳腺癌发病风险降低有关（OR=0.69,95% CI：0.48～1.00）;与不参加体育活动者相比,参加体育活动对乳腺癌发病有保护作用（OR=0.61,95% CI：0.43～0.87）;与久坐不动的职业相比,轻度职业活动对乳腺癌发病有保护作用（OR=0.67,95% CI：0.47～0.97）,而家务活动与乳腺癌发病风险无关。不同雌激素受体（estrogen receptor,ER）和孕激素受体（progesterone receptor,PR）状态的亚组分析中,非职业性体力活动与ER+/PR+乳腺癌的发病风险降低有关。结论 非职业性体力活动、体育活动和轻度职业活动对女性乳腺癌有保护作用。     

肺癌危险因素配对分配中对照人群选择的探讨

目的 探讨肺 危险因素配对分析中人群对照的选择方法,为开展肺癌危险因素监测 提供依据。方法 利用《常见恶性肿瘤发病、死亡及危险因素监测方法研究》课题中北京、天津、上海、重庆４市城区的调查资料,运用条件ｌｏｇｉｓｔｉｃ回归分析方法对３组１：１邻居,１：１正常人,１：２正常人匹配病例对照资料进行分析。结果 ３组资料肺癌主要危险因素的ＯＲ值一致,食物因素等的结果有一定差异;邻居对照和正常人对照因素暴露率     

Reliability of data from next-of-kin: results from a case-control study of occupational and lifestyle risk factors for cancer

BACKGROUND: Use of surrogate responders often needs to be considered in case-control studies with a high case fatality. METHODS: Agreement between 98 colon cancer patients and their closest relative was expressed as a percentage of the exact agreement and by Kappa coefficients and intra-class correlation coefficients. RESULTS: The percentage of "don't know" answers was higher for surrogates than for index cases and the highest percentage was seen for questions on early events like childhood diseases. Agreement was best for responses to dichotomous questions on smoking and for prevalent or chronic diseases like diabetes or psoriasis, and lower (54-64%) when a quantitative response of, e.g., smoking was requested. The next-of-kin reported fewer job periods than the study person, 4.5 and 2.8, respectively, and there was a higher agreement for the latest job held than for the longest held job. We found an overall agreement between 91% and 100% for responses to ever having worked in a specific type of industry or occupation. CONCLUSIONS: Use of next-of-kin data will often be a better alternative than excluding severely ill or deceased cases, if the exposure under study correlates with disease progression.     

Occupation and breast cancer risk in Polish women: a population-based case-control study

BACKGROUND: The etiology of breast cancer is not well understood and the role of occupational exposures in breast carcinogenesis is still uncertain. METHODS: The population-based case-control study included 2,386 incident breast cancer cases diagnosed in 2000-2003, and 2,502 controls. Lifetime occupational histories and information on other potential breast cancer risk factors were obtained through personal interviews. Conditional logistic regression analyses calculated odds ratios (ORs) associated with various occupations and industries after control for potential confounders. RESULTS: We found statistically significant excesses of breast cancer among engineers (OR=2.0; 95% CI: 1.0-3.8), economists (2.1; 1.1-3.8), sales occupations-retail (1.2; 1.0-1.5), and other sales occupations (1.2; 1.0-1.5). Industries showing significantly elevated risks included special trade contractors (2.2; 1.2-4.3), electronic and electric equipment manufacturers (1.7; 1.1-2.7); and public administration/general government n.e.c. (2.7; 1.3-5.7). Each of these findings was supported by a statistically significant positive trend for duration of employment (P<0.05). A decreased breast cancer risk was observed in janitors and cleaners (0.7; 0.5-0.8). CONCLUSIONS: In this study, we found few associations for breast cancer and occupations or industries. The suggestive findings for the electronic and electric equipment manufacturing industry and for the occupations with potential exposure to magnetic fields deserve further evaluation.     

上消化道三种恶性肿瘤的危险因素分析

目的 探讨我国食管癌、胃癌高发区目前上消化道3种恶性肿瘤发病的危险因素.方法 选择食管癌高发区河北省磁县、涉县,河南省林县和山东省肥城,胃癌高发区辽宁省庄河,每个地区分别从肿瘤登记数据库中选择发病日期为2009年1月1日以后的新诊断病例,利用随机数字表法选取食管下段癌、贲门癌、其他部位胃癌病例,共收集751例;按照病例与对照1∶3配对选取对照人群2253名.采用课题设计的调查表收集研究对象相关资料,并对相关变量进行单因素及多因素logistic回归分析,估计各危险因素的OR值(95%CI).结果 饮食不规律、经常食用油炸食品、有消化道病史及胃食管反流性疾病史者病例组分别有66、83、369、282例,而对照组分别为90、214、119、432名.单因素分析显示,以上因素可增加上消化道肿瘤发病风险[OR值(95%CI)分别为3.177(2.127～4.745)、3.190(2.061～4.927)、14.660(11.342～18.948)、3.137(2.546～3.864)];而常吃新鲜蔬菜者病例组中有387例,对照组有1278名,此因素可降低上消化道肿瘤发病风险(OR=0.609;95%CI:0.473～0.785).多因素分析显示,消化道病史(OR=21.420;95%CI:15.484～29.632)、饮食不规律(OR=3.097;95%CI:1.740～5.514)、经常食用腌晒食品(OR=3.005;95%CI:1.873～4.819)、胃食管反流性疾病史(OR=2.261;95%CI:1.673～3.057)等是上消化道肿瘤的危险因素;每天食用新鲜蔬菜(OR=0.562;95%CI:0.396～0.800)是上消化道肿瘤的保护因素.结论 不良生活方式和不健康饮食习惯是我国食管癌、胃癌高发区居民上消化道恶性肿瘤的危险因素.

Abstract：

Objective To explore the major risk factors for upper gastrointestinal cancer in high occurrence areas of esophageal and gastric cancer in China. Methods Four high occurrence areas of esophageal cancer, namely Cixian and Shexian from Hebei province, Linxian from Henan province, Feicheng from Shandong province, and Zhuanghe from Liaoning province, which is a high occurrence area of gastric cancer,were selected for the study. The newly-diagnosed cases whose date of onset were after January 1st,2009 were selected from the Cancer Registration Database in each district, and 751 cases diagnosed as cancers in lower segment of esophagus, cardiac and other subsite of stomach were randomly recruited. 2253 matched controls were selected to pair the cases at the ratio of 3: 1. The relative information of the study objects were collected from the face-to-face interviews with trained staff by designed questionnaires, and the data was input by EpiData software. Statistic software SPSS 13.0 was applied to conduct both univariate and multivariate logistic regression analysis to evaluate odd ratios (OR) and 95% confident interval (CI).Results As univariate analysis shown,66 objects in case group had irregular diet habit; while 90 in control group had ( OR= 3. 177;95% CI: 2. 127 - 4.745). A higher percentage in case group (83 objects)preferred fried food in comparison with only 214 in control group did (OR= 3. 190; 95% CI: 2.061 -4. 927). 369 objects in case group, but only 119 in control group had history of gastrointestinal diseases ( OR = 14. 660; 95% CI: 11. 342 - 18. 948 ). 282 objects in case group had history of gastroesophageal reflux disease (GERD) ,which was much higher than the percentage in control group (432 objects),with OR =3. 137 (95% CI: 2. 546 -3. 864). All the above factors could increase the risk for upper gastrointestinal cancer. 387 objects in case group and 1278 in control group reported they preferred fresh vegetables in daily diet,which was found to be a protective factor ( OR = 0. 609; 95% CI: 0. 473 - 0. 785 ). As multivariate analysis shown, history of gastrointestinal tract diseases ( OR = 21. 420; 95% CI: 15.484 - 29. 632 ),irregular food diet (OR=3.097; 95%CI: 1.740-5.514),pickled food (OR=3.005; 95%CI: 1.873 -4. 819) ,and GERD ( OR = 2. 261; 95% CI: 1. 673 - 3.057 ) were found to be risk factors for upper gastrointestinal cancer; while frequent fresh-vegetable diet was a protective factor (OR = 0. 562; 95% CI:0. 396 -0. 800). Conclusion Irregular lifestyle and unhealthy diet habit could be the major risk factors for upper gastrointestinal cancers among the residents from high occurrence areas of esophageal cancer and gastric cancer in China.     

Lung cancer risk and welding: Results from a case-control study in Germany

In a case-control study, 839 male hospital-based cases of primary lung cancer and the same number of population-based controls—matched by sex, age, and region of residence—were personally interviewed for their job and smoking histories. The study allows to quantify occupational asbestos exposure that was thought to be a welding-associated risk: 6% of cases and 2% of controls were classified into the occupational category “welders or burners” (odds ratio [OR] = 2.65). This OR was reduced to 1.93 (95% confidence limit [CL]: 1.03–3.61) after adjustment for smoking and asbestos. In contrast, a history of welding in general for at least a half-year is 28% among cases and 23% among controls, yielding an OR of 1.25 (95% CL: 0.94–1.65) after adjustment for both confounders. The OR of welding for more than 6,000 hr is 1.45 (95% CL = 1.04–2.02), reduced to 1.10 after adjustment for smoking and asbestos. Oxyacetylene welding for more than 6,000 hr lifelong is associated with an OR of 1.86 (95% CL = 1.01–3.43) reduced to 1.46 (n.s.) after adjustment for smoking and asbestos. The risk of oxyacetylene welding seems to be highest for oat cell carcinoma with an adjusted OR for ever-exposure of 1.46 (95% CL = 0.69–3.10). Therefore, the present study supports the hypothesis that some, but not all, of the excess risk of welders observed in the literature may be due to a history of cigarette smoking and occupanional asbestos exposure. The elevated risk for the subgroup of employees in the aircraft industry reported for the midterm evaluation of the study still prevails, though no longer statistically significant. However, employees in this industry who ever welded show an OR of 2.29 (95% CL = 1.19–4.42) after adjustment for smoking and asbestos. Am. J. Ind. Med. 33:313–320, 1998. © 1998 Wiley-Liss, Inc.     

Occupation and the occurrence of testicular cancer.

To investigate what role a man's occupation may have on his risk of testicular cancer, we conducted a case-control study among noncryptorchid white males who were between 20 and 69 years of age and resided in western Washington State. Cases were men in whom a germ cell tumor of the testis was diagnosed between 1977 and 1984 (n = 323). Their occupational histories were compared to those of controls of the same age, race, and geographic area who were selected through random-digit dialing (n = 658). Administrators/managers (relative risk (RR) = 1.5), salesmen (RR = 1.5), electricians (RR = 2.8), and sailors and fishermen (RR = 3.1) were among the jobs reported more commonly by cases than controls. The risk among farmers/farm managers was also elevated (RR = 1.9), but not that among farm workers (RR = 0.6). No consistent association between any one occupation and testicular cancer has been observed across studies of this topic. The most frequent observation has been an over-representation among cases of certain types of white collar worker; this may reflect the influence of some other aspect of socioeconomic status and not occupational exposures per se.     

A case-control study of the relationship between the risk of colon cancer in men and exposures to occupational agents

BACKGROUND: We conducted a population-based case-control study in Montreal, Canada, to explore associations between hundreds of occupational circumstances and several cancer sites, including colon. METHODS: We interviewed 497 male patients with a pathologically confirmed diagnosis of colon cancer, 1514 controls with cancers at other sites, and 533 population-based controls. Detailed job histories and relevant potential confounding variables were obtained, and the job histories were translated by a team of chemists and industrial hygienists into a history of occupational exposures. RESULTS: We found that there was reasonable evidence of associations for men employed in nine industry groups (adjusted odds ranging from 1.1 to 1.6 per a 10-year increase in duration of employment), and in 12 job groups (OR varying from 1.1 to 1.7). In addition, we found evidence of increased risks by increasing level of exposures to 21 occupational agents, including polystyrene (OR for "substantial" exposure (OR(subst)) = 10.7), polyurethanes (OR(subst) = 8.4), coke dust (OR(subst) = 5.6), mineral oils (OR(subst) = 3.3), polyacrylates (OR(subst) = 2.8), cellulose nitrate (OR(subst) = 2.6), alkyds (OR(subst) = 2.5), inorganic insulation dust (OR(subst) = 2.3), plastic dusts (OR(subst) = 2.3), asbestos (OR(subst) = 2.1), mineral wool fibers (OR(subst) = 2.1), glass fibers (OR(subst) = 2.0), iron oxides (OR(subst) = 1.9), aliphatic ketones (OR(subst) = 1.9), benzene (OR(subst) = 1.9), xylene (OR(subst) = 1.9), inorganic acid solutions (OR(subst) = 1.8), waxes, polishes (OR(subst) = 1.8), mononuclear aromatic hydrocarbons (OR(subst) = 1.6), toluene (OR(subst) = 1.6), and diesel engine emissions (OR(subst) = 1.5). Not all of these effects are independent because some exposures occurred contemporaneously with others or because they referred to a group of substances. CONCLUSIONS: We have uncovered a number of occupational associations with colon cancer. For most of these agents, there are no published data to support or refute our observations. As there are few accepted risk factors for colon cancer, we suggest that new occupational and toxicologic studies be undertaken focusing on the more prevalent substances reported herein.     

Infections and risk of type I diabetes in childhood: a population-based case-control study

Objective: This study focuses on the evaluation of some infectious diseases as risk determinants of type I diabetes mellitus (DM). Methods: A population-based case–control study was carried out by referring to the type I DM population-based register of the Abruzzo region of Italy as it includes all type I DM cases since January 1 1990, the point at which the register became operative. The pediatric population (age: 0–14), living in the same municipalities of the cases, was selected as the control population. Data were collected through questionnaires submitted by a physician to parents of cases and controls. Conditional logistic regression models were used to evaluate association between determinants and onset of type I DM. Results: The risk of diabetes for children exposed to only one infection (morbilli, parotitis, rubella, pertussis or varicella) is not statistically significant: OR: 0.778; CI: 0.427–1.370. On the contrary, when two infections are contracted statistically significant results occur: OR: 2.375; CI: 1.149–4.914; for more than two infections values are: OR: 6.786; CI: 2.881–17.877. No substantial difference in odds ratios (ORs) after adjustment for confounding variables was found. A significant decrease in OR was noted for pertussis and MMR vaccinations, respectively: OR: 0.015; CI: 0.001–0.251; OR: 0.400; CI: 0.201–0.799. Conclusions: Since the higher the number of contracted infections, the higher the risk of diabetes, contracted infections can be considered potential accelerating factors of clinical manifestation of type I DM. Therefore multiple exposures might speed up the onset of diabetes in children. This study suggests the utility of applying the risk model method to wider populations, especially if the geographical variability of standardised incidence rates of type I DM in pediatric age is taken into consideration.     

Sample size evaluation for a multiply matched case-control study using the score test from a conditional logistic (discrete Cox PH) regression model

The conditional logistic regression model (Biometrics 1982; 38:661-672) provides a convenient method for the assessment of qualitative or quantitative covariate effects on risk in a study with matched sets, each containing a possibly different number of cases and controls. The conditional logistic likelihood is identical to the stratified Cox proportional hazards model likelihood, with an adjustment for ties (J. R. Stat. Soc. B 1972; 34:187-220). This likelihood also applies to a nested case-control study with multiply matched cases and controls, selected from those at risk at selected event times. Herein the distribution of the score test for the effect of a covariate in the model is used to derive simple equations to describe the power of the test to detect a coefficient theta (log odds ratio or log hazard ratio) or the number of cases (or matched sets) and controls required to provide a desired level of power. Additional expressions are derived for a quantitative covariate as a function of the difference in the assumed mean covariate values among cases and controls and for a qualitative covariate in terms of the difference in the probabilities of exposure for cases and controls. Examples are presented for a nested case-control study and a multiply matched case-control study.