Registry-based case-control studies of liver cancer and cancers of the biliary tract nested in a cohort of autoworkers exposed to metalworking fluids

OBJECTIVE: Results are presented for a registry-based study of hepatobiliary cancer (liver and biliary tract) nested in a cohort of workers from three automobile manufacturing plants with potential exposure to metalworking fluids. METHODS: Altogether 63 cases of hepatobiliary cancer were identified from the cohort by the Michigan cancer registries. Each case was matched to 10 controls. Odds ratios (OR) were estimated in conditional logistic regression models for lifetime exposure to straight, soluble, and synthetic metalworking fluid and fluid components. RESULTS: Overall, hepatobiliary cancer was not associated with exposure to metalworking fluids. However, when the cases were stratified into liver cancer (N = 39) and biliary tract cancer (N = 24) the risk was nonhomogeneous across the two categories. While liver cancer was not associated with exposure to metalworking fluids, the results suggested a possible excess risk of biliary tract cancer with more than 1.0 mg/m3-years of exposure to straight metalworking fluids [OR 2.7, 95% confidence interval (95% CI) 0.9-7.6], as well as any exposure to chlorinated paraffins (OR 3.9, 95% CI 0.9-17). When exposures to straight metalworking fluids were separated into 10-year exposure periods, the odds ratio increased to 6.24 (95% CI 1.62-24.16) for exposures occurring > 20 years prior to the risk date. CONCLUSIONS: There is limited evidence that exposure to straight metalworking fluids is associated with biliary tract cancer. The small numbers of cases of these rare cancers were reflected in the wide confidence intervals, and these findings need to be examined further in other exposed populations.     

胆道系统肿瘤患者生存预测模型的构建及验证研究

目的 调查胆道系统肿瘤患者的生存率及其影响因素，并构建预后风险预测模型对生存概率进行预测。方法 选取美国监测、流行病学和结果项目（SEER）收集的2010-2015年诊断的14 005例胆道系统肿瘤（包括胆囊癌、肝外胆管癌和壶腹癌）患者作为观察人群。运用多因素Cox回归模型调查胆道系统肿瘤预后因素，并构建预测列线图对其1、3和5年总生存率进行预测并进行模型预测区分能力和标定能力评价。同时，选取SEER 2004-2009年诊断的11 953例患者作为验证队列对模型的外部预测准确性进行验证。结果 胆道系统肿瘤患者1、3和5年总生存率分别为41.9%、20.4%和15.3%。年龄>50周岁、黑人/印第安/阿拉斯加人种、较高的TNM分期及较差组织学分化程度是患者死亡的危险因素，而已婚状态、亚裔和太平洋岛人种、有医疗保险和原发部位手术是保护因素，性别与预后无关。预测模型C统计量为0.73（95%CI：0.72~0.74），标准曲线显示胆道系统肿瘤患者1、3和5年预测生存概率和实际生存概率交互曲线均与45°对角线接近。验证队列的结果与建模队列相似，预测模型C统计量0.70（95%CI：0.69~0.72），提示该预测模型具有较高的外部适用性。胆囊癌、肝外胆管癌和壶腹癌与总体胆道系统肿瘤结果一致。结论 胆道系统肿瘤患者生存率相对较差，基于预后因素构建的生存预测模型具有较高的预测准确性。未来可将该预测模型应用于临床，指导患者的个体化治疗。     

Occupation, pesticide exposure and risk of multiple myeloma

OBJECTIVES: This population-based case-control study examined the relationship between occupation, living or working on a farm, pesticide exposure, and the risk of multiple myeloma. METHODS: The study included 573 persons newly diagnosed with myeloma and 2131 controls. Information was obtained on sociodemographic factors, occupational history, and history of living and working on a farm. Occupational and industrial titles were coded by standardized classification systems. A job-exposure matrix was developed for occupational pesticide exposure. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated by unconditional logistic regression. RESULTS: Farmers and farm workers had odds ratios of 1.9 (95% CI 0.8-4.6) and 1.4 (95% CI 0.8-2.3), respectively. An odds ratio of 1.7 (95% CI 1.0-2.7) was observed for sheep farm residents or workers, whereas no increased risks were found for cattle, beef, pig, or chicken farm residents or workers. A modestly increased risk was observed for pesticides (OR 1.3, 95% CI 0.9-1.8). Significantly increased risks were found for pharmacists, dieticians and therapists (OR 6.1, 95% CI 1.7-22.5), service occupations (OR 1.3, 95% CI 1.02-1.7), roofers (OR 3.3, 95% CI 1.1-9.8), precision printing occupations (OR 10.1, 95% CI 1.03-99.8), heating equipment operators (OR 4.7, 95% CI 1.4-15.8), and hand molders and casters (OR 3.0, 95% CI 1.0-8.4). CONCLUSIONS: A modest increased risk of multiple myeloma is suggested for occupational pesticide exposure. The increased risk for sheep farm residents or workers indicates that certain animal viruses may be involved in myeloma risk.     

The association between frequency of vigorous physical activity and hepatobiliary cancers in the NIH-AARP Diet and Health Study

Despite a potential preventive effect of physical activity on hepatobiliary cancer, little information is available on the relation between the two. We studied the association between frequency of vigorous physical activity and hepatobiliary cancer among 507,897 participants of the NIH-AARP Diet and Health Study, aged 50–71 years at baseline in 1995/1996. During 10 years of follow-up, 628 incident cases of liver cancer and 317 cases of extrahepatic biliary tract cancer were registered. Physical activity levels were assigned according to the frequency of engagement in 20 min or more of vigorous physical activity per week: never/rarely (lowest level), less than once per week, 1–2 times per week, 3–4 times per week, 5 or more times per week (highest level). Using Cox regression, multivariate-adjusted relative risks (RR) comparing the highest with the lowest level of physical activity revealed a statistically significant decreased risk for liver cancer (RR = 0.64, 95 % confidence interval (CI) = 0.49–0.84, p-trend <0.001), particularly hepatocellular carcinoma (RR = 0.56, 95 % CI = 0.41–0.78, p-trend <0.001), independent of body mass index. By comparison, multivariate analyses indicated that physical activity was not statistically significantly associated with extrahepatic bile duct cancer (RR = 0.86, 95 % CI = 0.45–1.65), ampulla of Vater cancer (RR = 0.66, 95 % CI = 0.29–1.48), or gallbladder cancer (RR = 0.63, 95 % CI = 0.33–1.21). These results suggest a potential preventive effect of physical activity on liver cancer but not extrahepatic biliary tract cancer, independent of body mass index.     

Occupation and cancer of the oral cavity or oropharynx in Turin, Italy

In a population-based case-referent study, the occupational experience of 86 men with oral or oropharyngeal cancer and 373 referents was analyzed with respect to employment in 41 occupations and 40 industries, as well as to exposure to 16 chemicals, as estimated via a job-exposure matrix. Among the occupations and industries at higher risk were machinery operator (odds ratio [OR] 2.0; 95% confidence interval [95% CI] 1.0-4.0), plumber (OR 5.0, 95% CI 1.2-21.5), building industry (OR 2.5; 95% CI 1.3-4.5), textile industry (OR 2.5; 95% CI 0.6-4.6), and electricity production (OR 2.8; 95% CI 0.7-12.1). All the OR estimates were adjusted for age, education, area of birth, tobacco smoking, and alcohol consumption. An association between formaldehyde exposure and oral cancer was suggested (OR for any exposure 1.6, 95% CI 0.9-2.8; OR for probable or definite exposure 1.8, 95% CI 0.6-5.5). No other chemical included in the matrix showed any risk pattern. The evidence of an association between formaldehyde exposure and oral or oropharyngeal cancer is strengthened by the results of this study.     

鞍钢工人的肿瘤危险度——肺癌病例-对照研究

对鞍钢男工中６１０例肺癌新发病例及９５９例对照进行了访问调查。经吸烟、其他肺疾患、家族肿瘤史、食用水果等非职业因素调整后，岗位工龄等于或超过１５年的下列工人的肺癌危险度显著增高：冶炼工和轧钢工（ＱＲ＝１．５，９５％ＣＩ＝１．１～２．２），耐火砖厂工（ＯＲ＝２．９，９５％ＣＩ＝１．４～５．９），装卸工（ＯＲ＝２．５，９５％ＣＩ＝１．０～６．１），焦炉工（ＯＲ＝３．４，９５％ＣＩ＝１．４～８．５）。各种粉尘和Ｂ［ａ］Ｐ暴露与肺癌危险性呈显著的剂量－反应关系，但与粉尘的特殊成分未见此种关联。长期暴露于污染物的钢铁工人的肺癌的危险度增加４０％。     

Alcohol consumption and the risk of gastric cancer

The relationship between alcohol drinking and gastric cancer risk was analyzed using data from a case-control study conducted in Northern Italy between 1985 and 1993 on 746 cases of histologically confirmed incident stomach cancer and 2,053 controls in hospital for acute nonneoplastic nondigestive tract diseases. Wine was the most frequently consumed alcoholic beverage, accounting for approximately 90% of all alcohol consumption. Compared with those who never drank wine, the odds ratios (OR) were 1.1 [95% confidence interval (CI) 0.9-1.3] for fewer than four drinks per day, 1.3 (95% CI 1.0-1.7) for four to fewer than six drinks per day, 1.6 (95% CI 1.1-2.4) for six to fewer than eight drinks per day, and 1.4 (95% CI 1.0-2.0) for eight or more drinks per day. No association was observed with beer or spirits. For total alcohol consumption, 25% of cases and 30% of controls never drank alcohol, and the multivariate OR for those who drank versus those who did not drink was 1.1 (95% CI 0.9-1.4). After allowance for smoking, education, family history of stomach cancer, selected micronutrient intake, and nonalcohol calorie intake, the ORs were 1.1 (95% CI 0.9-1.4) for fewer than six drinks per day, 1.0 (95% CI 0.4-1.4) for six to fewer than eight drinks per day, and 1.3 (95% CI 0.9-1.9) for eight or more drinks per day, and the trend in risk was not significant. No interaction was observed between alcohol drinking and sex, family history, and smoking, but the association with alcohol drinking was appreciably stronger in the elderly and in less-educated individuals. Thus this large data set was able to exclude a strong and consistent association between alcohol (mainly wine) drinking and stomach cancer risk. A nonsignificant association was observed in those who drank very heavily, but the absence of a dose-risk relationship suggests that even such a moderate association may reflect inadequate allowance for covariates or the presence of other risk factors (possibly related to diet and social class) among the heaviest drinkers.     

Maternal, delivery, and perinatal characteristics associated with cryptorchidism: a population-based case-control study among births in Washington State

BACKGROUND: The etiology of cryptorchidism is largely unknown. To identify maternal, perinatal, and delivery characteristics associated with cryptorchidism at birth, we conducted a population-based case-control study using Washington State birth certificates linked to birth hospitalization records. METHODS: We identified 2,395 cases of cryptorchidism among male infants born in Washington State during 1986-1996, and, for comparison, we randomly selected four controls per case (N = 9,580), frequency-matched by year of birth. RESULTS: Infant characteristics associated with cryptorchidism included low birth weight (OR = 1.5; 95% CI = 1.3-1.8), small size for gestational age (OR = 1.9; 95% CI = 1.6-2.2), and breech presentation (OR = 1.7; 95% CI = 1.4-2.1). In addition to cryptorchidism, cases were more likely to have another type of congenital malformation (OR = 3.7; 95% CI = 3.2-4.2), particularly digestive (OR = 6.8; 95% CI = 3.7-12.7) or genitourinary (OR = 4.1; 95% CI = 3.0-5.6). Maternal and pregnancy characteristics associated with cryptorchidism included nulliparity (OR = 1.2; 95% CI = 1.1-1.3), maternal smoking during pregnancy (OR = 1.2; 95% CI = 1.1-1.4), and the following pregnancy complications: oligohydramnios (OR = 1.8; 95% CI = 1.3-2.6), placental abnormality (OR = 1.3; 95% CI = 1.0-1.8), and pregnancy-induced hypertension (OR = 1.6; 95% CI = 1.4-1.9). Odds ratios were similar when the analysis was restricted to term infants. CONCLUSIONS: These findings suggest that factors affecting fetal growth and development may increase the risk of cryptorchidism.     

Risk factors for community-acquired pneumonia in German adults: the impact of children in the household

The objective of this case-control study was to identify the main risk factors for community-acquired pneumonia (CAP) in a German adult population. A self-administered questionnaire was given to CAP cases provided by the German competence network CAPNETZ and population-based, randomly selected controls (sex- and age-matched). Multivariate analysis showed that in addition to known risk factors such as previous CAP [odds ratio (OR) 1.6, 95% confidence interval (CI) 1.3-2.1], more than one respiratory infection during the previous year (OR 3.6, 95% CI 2.9-4.5), chronic pulmonary diseases (OR 2.3, 95% CI 1.7-3.0), number of comorbidities (OR 1.6, 95% CI 1.4-1.9), and number of children in the household (2 children: OR 2.2, 95% CI 1.5-3.4; > or = 3 children: OR 3.2, 95% CI 1.5-7.0) were independent risk factors for CAP. This was pronounced in particular in people aged < or = 65 years. The most likely explanation for this finding is higher exposure to infectious agents.     

Parental occupational exposure to pesticides and childhood germ-cell tumors

In a recently completed US case-control study (Children's Oncology Group, 1993-2001) with 253 cases and 394 controls, the authors investigated the association between parental occupational exposure to pesticides and risk of childhood germ-cell tumors. Information on occupational pesticide exposure was collected using job-specific module questionnaires and assessed by an experienced industrial hygienist. Odds ratios for childhood germ-cell tumors associated with maternal exposures before pregnancy, during pregnancy, and after the birth of the index child were 1.0 (95% confidence interval (CI): 0.8, 1.4), 1.1 (95% CI: 0.7, 1.6), and 1.3 (95% CI: 0.9, 1.8), respectively. Paternal exposures before pregnancy, during pregnancy, and after the birth of the index child were not related to germ-cell tumors (odds ratios (ORs) were 0.9 (95% CI: 0.7, 1.2), 0.8 (95% CI: 0.5, 1.2), and 0.8 (95% CI: 0.5, 1.3), respectively). When both parents had ever been occupationally exposed to pesticides before the index pregnancy, the odds ratio was 0.8 (95% CI: 0.4, 1.3). Subgroup analyses showed a positive association between maternal exposure to herbicides during the postnatal period and risk of germ-cell tumors in girls (OR = 2.3, 95% CI: 1.0, 5.2) and an inverse association between paternal exposure to pesticides during the index pregnancy and germ-cell tumors in boys (OR = 0.2, 95% CI: 0.1, 1.0). This study did not provide strong evidence supporting a relation between parental pesticide exposure in the workplace and risk of germ-cell tumors among offspring.     

Occupational history and exposure and the risk of adult leukemia in Shanghai

PURPOSE: Evaluation of the association of selected occupational exposures with leukemia risk. METHODS: Population-based case-control study of 486 leukemia subjects and 502 healthy controls residing in Shanghai from 1987 to 1989. Adjusted odds ratios (OR) were calculated for the association between occupational factors and leukemia risk. RESULTS: Significant increase in leukemia risk was observed in chemical manufacturing industry workers (OR=3.1, 95% CI=1.0-9.8). Increased risks for leukemia were observed from self-reported exposures to benzene (OR=1.7, 95% CI=1.1-2.6), radioactive materials (OR=3.7, 95% CI=1.3-10.2), synthetic fiber dust (OR=2.0, 95% CI=1.2-3.5), and toluene (OR=1.6, 95% CI=1.0-2.5). Dose-response relations of leukemia risk was observed with the duration of exposure to benzene (OR=3.3, 95% CI=1.6-6.9 for >or=15 years exposure; p for trend<0.01), radioactive materials (OR=5.2, 95% CI=1.1-24.7 for >or=15 years exposure; p for trend=0.02), paints (OR=2.3, 95% CI=1.2-4.7 for >or=15 years exposure; p for trend=0.09), and toluene (OR=2.9, 95% CI=1.3-6.7 for >or=15 years exposure; p for trend=0.02). CONCLUSIONS: Adult leukemia risk may be associated with working in the chemical industry, and exposure to benzene, synthetic fiber dust, radioactive materials, and toluene in the study population.     

Occupational risk factors for renal cell carcinoma: agent-specific results from a case-control study in Germany. MURC Study Group. Multicenter urothelial and renal cancer study

BACKGROUND: This case-control study was conducted to estimate the renal cell cancer (RCC) risk for exposure to occupation-related agents, besides other suspected risk factors. METHODS: In a population-based multicentre study, 935 incident RCC cases and 4298 controls matched for region, sex, and age were interviewed between 1991 and 1995 for their occupational history and lifestyle habits. Agent-specific exposure was expert-rated with two job-exposure matrices and a job task-exposure matrix. Conditional logistic regression was used to calculate smoking adjusted odds ratios (OR). RESULTS: Very long exposures in the chemical, rubber, and printing industries were associated with risk for RCC. Males considered as 'substantially exposed to organic solvents' showed a significant excess risk (OR = 1.6, 95% CI : 1.1-2.3). In females substantial exposure to solvents was also a significant risk factor (OR = 2.1, 95% CI : 1.0-4.4). Excess risks were shown for high exposure to cadmium (OR = 1.4, 95% CI : 1.1-1.8, in men, OR = 2.5, 95% CI : 1.2-5.3 in women), for substantial exposure to lead (OR = 1.5, 95% CI : 1.0-2.3, in men, OR = 2.6, 95% CI : 1.2-5.5, in women) and to solder fumes (OR = 1.5, 95% CI : 1.0-2.4, in men). In females, an excess risk for the task 'soldering, welding, milling' was found (OR = 3.0, 95% CI : 1.1-7.8). Exposure to paints, mineral oils, cutting fluids, benzene, polycyclic aromatic hydrocarbons, and asbestos showed an association with RCC development. CONCLUSIONS: Our results indicate that substantial exposure to metals and solvents may be nephrocarcinogenic. There is evidence for a gender-specific susceptibility of the kidneys.     

Increased concentrations of polychlorinated biphenyls,hexachlorobenzene, and chlordanes in mothers of men with testicular cancer

An increasing incidence of testicular cancer has been reported from several countries in the Western world during the last decades. According to current hypothesis, testicular cancer is initiated during the fetal period, and exposure to endocrine disruptors, i.e., xenoestrogens, has been of concern. In this investigation we studied the concentrations of the sum of 38 polychlorinated biphenyls (PCBs), p,p'-dichlorodiphenyl-dichloroethylene, hexachlorobenzene (HCB), and chlordanes, in 61 cases with testicular cancer and 58 age-matched controls. Furthermore, case and control mothers were also asked to participate, and 44 case mothers and 45 control mothers agreed. They were of similar age. In cases only the concentration on lipid basis of cis-nonachlordane was significantly increased, whereas case mothers showed significantly increased concentrations of the sum of PCBs, HCB, trans- and cis-nonachlordane, and the sum of chlordanes. Among case mothers the sum of PCBs yielded an odds ratio (OR) of 3.8; 95% confidence interval (CI), 1.4-10 was calculated using the median concentration for the control mothers as cutoff value. For HCB, OR = 4.4 (95% CI, 1.7-12); for trans-nonachlordane, OR = 4.1 (95% CI, 1.5-11); for cis-nonachlordane, OR = 3.1 (95% CI, 1.2-7.8); and for sum of chlordanes, OR = 1.9 (95% CI, 0.7-5.0). No consistent different risk pattern was found for seminoma or nonseminoma testicular cancer.     

Serum polychlorinated biphenyls, cytochrome P-450 1A1 polymorphisms, and risk of breast cancer in Connecticut women

Recent epidemiologic studies have suggested that genetic polymorphisms in the cytochrome P-450 1A1 gene (CYP1A1) may affect the relation between environmental exposure to polychlorinated biphenyls (PCBs) and breast cancer risk. The authors report results from a case-control study evaluating the potential effect of gene-environment interaction between CYP1A1 and serum PCB levels on breast cancer risk among Caucasian women in Connecticut. The study included 374 case women with histologically confirmed breast cancer and 406 noncancerous controls with information on both serum PCB level and CYP1A1 genotype (1999-2002). Compared with women who had the homozygous wild-type CYP1A1 m2 genotype, significantly increased risks of breast cancer were found for women with the CYP1A1 m2 variant genotype (odds ratio (OR) = 2.1, 95% confidence interval (CI): 1.1, 3.9), especially postmenopausal women (OR = 2.4, 95% CI: 1.1, 5.0). Risks associated with the CYP1A1 m2 variant genotype were highest for all women (OR = 3.6, 95% CI: 1.5, 8.2) and postmenopausal women (OR = 4.3, 95% CI: 1.6, 12.0) with higher serum PCB levels (611-2,600 ng/g). The CYP1A1 m1 and m4 genotypes were not associated with breast cancer risk independently or in combination with PCB exposure. In summary, the CYP1A1 m2 genetic polymorphism was associated with increased risk of female breast cancer and may modify the relation between PCB exposure and breast cancer risk.     

Occupation and the risk of laryngeal cancer in Turkey

OBJECTIVES: A hospital-based case-referent study was conducted in Turkey to provide further information on occupational risk factors and laryngeal cancer. METHODS: Among 7631 cancer cases seen at an oncology treatment center between 1979 and 1984, 958 laryngeal cancer cases were identified among men. Occupational history, tobacco and alcohol use, and demographic data were obtained from patients with a standardized questionnaire. Special 7-digit standard occupational and industrial codes were created to classify the job and industrial titles of the subjects. After exclusions, 940 laryngeal cancer cases and 1519 referents were available for study. Age-, smoking- and alcohol-adjusted odds ratios (OR) and 95% confidence intervals (95% CI) were calculated. RESULTS: Excess laryngeal cancer occurred among guards (OR 1.5, 95% CI 1.1-2.1), production supervisors (OR 1.8, 95% CI 1.1-3.1), textile workers (OR 1.9, 95% CI 1.2-3.3), drivers (OR 1.7, 95% CI 1.1-2.4), construction workers (OR 1.7, 95% Cl 1.2-2.6), and workers in grain mills (OR 3.1, 95% CI: 1.3-7.6), trade unions (OR 3.6, 95% CI: 1.1-11.7) and local government services (OR 4.7, 95% CI 1.7-12.5). Supraglottic cancer was excessive among the textile workers, construction workers, and local government laborers, all with potential dust exposure. The risks of the general managers, electricians, and workers from industries such as pharmaceutical production, industrial machinery production, electric utilities, and retail services were lower than expected. CONCLUSIONS: The risk of laryngeal cancer was associated with several occupations, and supraglottic larynx cancer appears to be more common among workers in dusty occupations and industries.     

A case-control study of occupational risk factors for laryngeal cancer.

To determine whether specific jobs and occupational exposures are associated with laryngeal cancer lifetime occupational histories from a population-based case-control study in western Washington were examined. The study included 235 cases diagnosed between September 1983 and February 1987, and 547 controls identified by random digit dialing. After controlling for alcohol use, cigarette smoking, age and education, significantly increased risks were found for painters in construction (odds ratio (OR)) = 2.8, (95% confidence interval (95% CI) 1.1-6.9), supervisors and miscellaneous mechanics (OR = 2.3, 95% CI 1.1-4.8), construction workers (OR = 3.4, 95% CI 1.4-8.1), metalworking and plastic working machine operators (OR = 2.6, 95% CI 1.3-4.9) and handlers, and equipment cleaners and labourers (OR = 1.5, 95% CI 1.0-2.2). Allowing for a 10 year induction and latent period did not have a consistent effect on the associations. Potential exposures to asbestos, chromium, nickel, formaldehyde, diesel fumes, and cutting oils were assessed by using a job exposure matrix developed for this study. Three measures of exposure were examined--namely, peak, duration, and an intensity weighted exposure score. No significantly raised risks were seen, although increased risk was suggested among those exposed long term to formaldehyde in jobs with the highest exposures.     

Biliary tract cancer and occupation in Sweden

Using the Cancer-Environment Registry, which links the incidence of cancer (1961-79) and the 1960 census data on industry and occupation for all employed individuals in Sweden, the occurrence of biliary tract cancer (ICD 7th rev 155.1-.9) was systematically assessed according to occupational and industrial classifications. Data are presented separately for cancer of the gall bladder (ICD 155.1) and other cancers of the biliary tract (ICD 155.2-.9) including cancers of the extrahepatic bile ducts, ampulla of Vater, and unspecified bile passages. Statistically significant increased risks for cancer of the gall bladder were observed for men employed in petroleum refining, papermills, chemical processing, shoemaking, and repairing, and for both men and women employed in textile work. A significant increase in the incidence of other cancers of the biliary tract (mostly cancers of the bile duct) was found for such asbestos related employment as shipbuilding and in the wholesale construction materials industry and among insulation workers. These findings should be considered only as clues to aetiological factors, although several are consistent with earlier observations from other countries.     

Biliary tract cancer and occupation in Sweden.

Using the Cancer-Environment Registry, which links the incidence of cancer (1961-79) and the 1960 census data on industry and occupation for all employed individuals in Sweden, the occurrence of biliary tract cancer (ICD 7th rev 155.1-.9) was systematically assessed according to occupational and industrial classifications. Data are presented separately for cancer of the gall bladder (ICD 155.1) and other cancers of the biliary tract (ICD 155.2-.9) including cancers of the extrahepatic bile ducts, ampulla of Vater, and unspecified bile passages. Statistically significant increased risks for cancer of the gall bladder were observed for men employed in petroleum refining, papermills, chemical processing, shoemaking, and repairing, and for both men and women employed in textile work. A significant increase in the incidence of other cancers of the biliary tract (mostly cancers of the bile duct) was found for such asbestos related employment as shipbuilding and in the wholesale construction materials industry and among insulation workers. These findings should be considered only as clues to aetiological factors, although several are consistent with earlier observations from other countries.     

Absence of an effect of injectable and implantable progestin-only contraceptives on subsequent risk of breast cancer

Animal data indicate that both estrogens and progestins could be carcinogenic and that progestins could serve as tumor promoters. Human studies have not confirmed an increased risk of breast cancer from long-term use of oral contraceptives, but have shown an increased risk from hormone replacement therapy including progestins. The present study analyzed the relationship between breast cancer and use of injectable and implantable progestin-only contraceptives. Analyses were performed on data collected in a population-based, multicenter, case-control study, the Women's Contraceptive and Reproductive Experiences Study of the National Institute of Child Health and Human Development. The study involved 4575 randomly sampled cases with invasive breast cancer diagnosed between 1994 and 1998, and 4682 controls, identified using random digit dialing. We assessed the association between exposure to injectable contraceptives and risk of breast cancer. The use of injectable contraceptives was not associated with an increased risk of breast cancer [odds ratio (OR) = 0.9, 95% confidence interval (CI): 0.7, 1.2]. Risk was not increased among current users, defined as women who used injectable contraceptives within 1 year of the reference date (OR = 0.7, 95% CI: 0.4, 1.3) or those who initiated use in the 5 years immediately preceding the reference date (OR = 0.9, 95% CI: 0.5, 1.4), or with use beginning before age 35 (OR = 0.9, 95% CI: 0.6, 1.3). Among users, risk increased with increasing duration of use (p = 0.03). However, short-term users (<6 months duration) were at decreased risk relative to never users (OR = 0.6, 95% CI: 0.4, 1.0). When the short-term users were then excluded from the duration-response analysis, the slope of the duration-response became slightly (and nonsignificantly) negative. Risk was not increased among women with 24 or more months of use relative to never users (OR = 1.4, 95% CI: 0.8, 2.5). No increased risk was seen from implantable contraceptives either, although the sample sizes were small. This study does not support an increased risk of breast cancer associated with the use of injectable or implantable progestin-only contraceptives in women aged 35 to 64.