Prepubertal ovarian inhibition of Light/Dark Box exploration and novel object investigation in juvenile Siberian hamsters.

The overwhelming majority of research on the role of gonadal hormones in behavioral development has focused on perinatal, pubertal, or adult life stages. The juvenile period has been overlooked because it is thought to be a time of gonadal quiescence. In the present study, we tested whether prepubertal gonadectomy impacts the behavior of male and female juvenile hamsters on the Light/Dark Box, Novel Object, and Social Approach tests (Experiment 1) and compared these findings to those obtained after adult gonadectomy (Experiment 2). Prepubertal ovariectomy increased exploration (i.e. time spent in the light zone of the Light/Dark Box) and novel object investigation of juveniles indicating an inhibitory role for the juvenile ovary; social approach was unaffected. In contrast, adult ovariectomy and castration (both prepubertal and adult) had no effect on any behavioral measure. Experiment 3 tested whether rearing hamsters in a short day length (SD), which delays puberty in this species, extends the interval of juvenile ovarian inhibition on exploration and novelty seeking. We also tested whether provision of estradiol reverses the effects of prepubertal ovariectomy. Hormonal manipulations and behavioral tests of Experiment 3 were conducted at ages when long day-reared hamsters are adult (as in Experiment 2), but SD-reared hamsters remain reproductively immature. Ovariectomy again increased exploration in the SD-reared juveniles despite the older age of surgery and testing. Estradiol treatment had no effect. These findings reveal a novel role for the juvenile ovary in exploration and novelty seeking that is unlikely to be mediated exclusively by estradiol.

Risk assessment of wandering behavior in mild dementia.

OBJECTIVE: This prospective longitudinal study aims to determine the risk factors of wandering-related adverse consequences in community-dwelling persons with mild dementia. These adverse consequences include negative outcomes of wandering (falls, fractures, and injuries) and eloping behavior. METHODS: We recruited 143 dyads of persons with mild dementia and their caregivers from a veteran's hospital and memory clinic in Florida. Wandering-related adverse consequences were measured using the Revised Algase Wandering Scale - Community Version. Variables such as personality (Big Five Inventory), behavioral response to stress, gait, and balance (Tinetti Gait and Balance), wayfinding ability (Wayfinding Effectiveness Scale), and neurocognitive abilities (attention, cognition, memory, language/verbal skills, and executive functioning) were also measured. Bivariate and logistic regression analyses were performed to assess the predictors of these wandering-related adverse consequences. RESULTS: A total of 49% of the study participants had falls, fractures, and injuries due to wandering behavior, and 43.7% demonstrated eloping behaviors. Persistent walking (OR = 2.6) and poor gait (OR = 0.9) were significant predictors of negative outcomes of wandering, while persistent walking (OR = 13.2) and passivity (OR = 2.55) predicted eloping behavior. However, there were no correlations between wandering-related adverse consequences and participants' characteristics (age, gender, race, ethnicity, and education), health status (Charlson comorbidity index), or neurocognitive abilities. CONCLUSION: Our results highlight the importance of identifying at-risk individuals so that effective interventions can be developed to reduce or prevent the adverse consequences of wandering.

Risk of treatment-related esophageal cancer among breast cancer survivors.

BACKGROUND: Radiotherapy for breast cancer may expose the esophagus to ionizing radiation, but no study has evaluated esophageal cancer risk after breast cancer associated with radiation dose or systemic therapy use. DESIGN: Nested case-control study of esophageal cancer among 289 748 ≥5-year survivors of female breast cancer from five population-based cancer registries (252 cases, 488 individually matched controls), with individualized radiation dosimetry and information abstracted from medical records. RESULTS: The largest contributors to esophageal radiation exposure were supraclavicular and internal mammary chain treatments. Esophageal cancer risk increased with increasing radiation dose to the esophageal tumor location (P(trend )< 0.001), with doses of ≥35 Gy associated with an odds ratio (OR) of 8.3 [95% confidence interval (CI) 2.7-28]. Patients with hormonal therapy ≤5 years preceding esophageal cancer diagnosis had lower risk (OR = 0.4, 95% CI 0.2-0.8). Based on few cases, alkylating agent chemotherapy did not appear to affect risk. Our data were consistent with a multiplicative effect of radiation and other esophageal cancer risk factors (e.g. smoking). CONCLUSIONS: Esophageal cancer is a radiation dose-related complication of radiotherapy for breast cancer, but absolute risk is low. At higher esophageal doses, the risk warrants consideration in radiotherapy risk assessment and long-term follow-up.

Infrared variability of the BL lacertae object OJ287 since its outburst in 1983.

In early 1983, OJ287 was seen to undergo an outburst in its optical and infrared emission1. Since then optical monitoring studies2-4 have shown a general decline in the source brightness, with considerable fluctuations. We have monitored the near-infrared emission since the outburst. The fluxes have fluctuated considerably, with the lowest recordings being an order of magnitude less than those measured during the outburst. We have found an excellent correlation between infrared flux and spectral index; as the source gets fainter the spectrum gets steeper, and vice versa. We interpret this in terms of outbursts being due to injection or reacceleration of electrons with a constant energy index which subsequently steepens as the electrons are affected by radiation losses.

Viral rescue of magnocellular vasopressin cells in adolescent Brattleboro rats ameliorates diabetes insipidus, but not the hypoaroused phenotype.

Dysregulated arousal often accompanies neurodevelopmental disorders such as attention deficit hyperactivity disorder and autism spectrum disorder. Recently, we have found that adolescent homozygous Brattleboro (Hom) rats, which contain a mutation in the arginine vasopressin (AVP) gene, exhibit lower behavioral arousal than their heterozygous (Het) littermates in the open field test. This hypoaroused phenotype could be due to loss of AVP in magnocellular cells that supply AVP to the peripheral circulation and project to limbic structures or parvocellular cells that regulate the stress axis and other central targets. Alternatively, hypoarousal could be a side effect of diabetes insipidus - polydipsia and polyuria seen in Hom rats due to loss of AVP facilitation of water reabsorption in the kidney. We developed a viral-rescue approach to "cure" magnocellular AVP cells of their Brattleboro mutation. Infusion of a recombinant adeno-associated virus (rAAV) containing a functional Avp gene and promoter (rAAV-AVP) rescued AVP within magnocellular cells and fiber projections of the paraventricular nucleus of the hypothalamus (PVN) of male and female adolescent Hom rats. Furthermore, water intake was markedly reduced, ameliorating the symptoms of diabetes insipidus. In contrast, open field activity was unaffected. These findings indicate that the hyporaoused phenotype of adolescent Hom rats is not due to the loss of AVP function in magnocellular cells or a side effect of diabetes insipidus, but favors the hypothesis that central, parvocellular AVP mechanisms underlie the regulation of arousal during adolescence.

Functionally distinct roles for different miR-155 expression levels through contrasting effects on gene expression, in acute myeloid leukaemia.

Enforced expression of microRNA-155 (miR-155) in myeloid cells has been shown to have both oncogenic or tumour-suppressor functions in acute myeloid leukaemia (AML). We sought to resolve these contrasting effects of miR-155 overexpression using murine models of AML and human paediatric AML data sets. We show that the highest miR-155 expression levels inhibited proliferation in murine AML models. Over time, enforced miR-155 expression in AML in vitro and in vivo, however, favours selection of intermediate miR-155 expression levels that results in increased tumour burden in mice, without accelerating the onset of disease. Strikingly, we show that intermediate and high miR-155 expression also regulate very different subsets of miR-155 targets and have contrasting downstream effects on the transcriptional environments of AML cells, including genes involved in haematopoiesis and leukaemia. Furthermore, we show that elevated miR-155 expression detected in paediatric AML correlates with intermediate and not high miR-155 expression identified in our experimental models. These findings collectively describe a novel dose-dependent role for miR-155 in the regulation of AML, which may have important therapeutic implications.

Environmental factors and high risk of esophageal cancer among men in coastal South Carolina.

A case-control study involving interviews of 207 men with esophageal cancer and 422 control subjects or their next of kin was conducted to identify reasons for the unusually high rates of esophageal cancer among men in coastal South Carolina. Tobacco and alcohol, including moonshine, were identified as the major determinants of esophageal cancer risk. Increased risk was also associated with low intake of fresh fruits but not with drinking of local herbal teas. The findings suggest that efforts aimed at reducing tobacco and alcohol use will help to lower the elevated rates of esophageal cancer in coastal South Carolina.

Testicular cancer risk among young men: role of cryptorchidism and inguinal hernia.

The role of cryptorchidism (undescended testis) and inguinal hernia in the etiology of testicular cancer among men aged 18-42 years was evaluated in a case-control study of 271 cases and 259 controls referred to three collaborating medical centers in the Washington, DC, area. The relative risk of testicular cancer for men who reported a history of an undescended testis was 3.7 (95% confidence interval = 1.6-8.6). The risk increased with increasing age at correction; the risk was highest for those men whose cryptorchid testis was never corrected. Among unilateral cryptorchids, no increased risk of testicular cancer was observed for the normally descended testis. There was only a slight excess risk for men without cryptorchidism who had a herniorrhaphy; however, those who underwent a hernia operation after age 7 had a significantly elevated risk of testicular cancer on the same side as the hernia. This case-control study is the first one to support the clinical recommendations for early surgical correction of cryptorchidism and inguinal hernia. Data from this study suggest that the excess cancer risk associated with cryptorchidism is due to internal factors that affect the undescended testis rather than to some underlying developmental abnormality.

Cigarette smoking and pancreas cancer: a case-control study based on direct interviews.

BACKGROUND: Cigarette smoking is the most consistently reported risk factor for pancreas cancer, yet the dose-response relationship in many pancreas cancer studies is weak. Because of the poor prognosis for pancreas cancer, many case-control studies have been based largely on interviews with proxy respondents, who are known to report less reliable information on detailed smoking habits than original subjects. PURPOSE: Our purpose was to evaluate cigarette smoking as a risk factor for pancreas cancer based on data obtained only from direct interviews and to estimate the effects of quitting smoking and of switching from nonfiltered to filtered cigarettes on risk. Our objective also was to estimate the contribution of cigarette smoking toward explaining the higher pancreas cancer incidence experienced by black Americans compared with white Americans. METHODS: A population-based, case-control study of pancreas cancer was conducted during 1986-1989 in Atlanta, Ga., Detroit, Mich., and 10 counties in New Jersey. Direct interviews were successfully completed with 526 case patients and 2153 control subjects aged 30-79 years, making this the largest population-based, case-control study of pancreas cancer to date based only on direct interviews. RESULTS: Cigarette smokers had a significant, 70% increased risk of pancreas cancer compared with the risk in nonsmokers. A significant, positive trend in risk with increasing duration smoked was apparent (P < .0001), with long-term (> or = 40 years) smokers experiencing a modest 2.1-fold risk. We also observed a negative trend in risk with increasing years quit smoking. Smokers who quit for more than 10 years experienced about a 30% reduction in risk relative to current smokers; quitters of 10 years or less experienced no risk reduction. Switching from nonfiltered to filtered cigarettes did not appear to decrease risk. Compared with nonsmokers, subjects who smoked only filtered cigarettes had a 50% elevated risk and those who smoked only nonfiltered cigarettes had a 40% elevated risk. The proportion of pancreas cancer attributable to cigarette smoking was 29% in blacks and 26% in whites. CONCLUSIONS: The relationship between cigarette smoking and pancreas cancer risk is likely to be causal, despite the weakness of the dose-response data. Long-term smoking cessation clearly reduces risk, whereas switching from nonfiltered to filtered cigarettes may not be beneficial. Cigarette smoking appears to explain little of the excess pancreas cancer risk experienced by blacks. IMPLICATIONS: Elimination of cigarette smoking would eventually prevent approximately 27% of pancreas cancer, saving 6750 lives in the United States annually.

Are racial differences in squamous cell esophageal cancer explained by alcohol and tobacco use?

BACKGROUND: In the United States, incidence rates of squamous cell esophageal cancer are more than five times higher among black men than among white men. Reasons that might explain this large racial disparity are being sought. PURPOSE: We evaluated whether differential use of alcohol and tobacco can fully account for the excess of squamous cell esophageal cancer among U.S. blacks. METHODS: We conducted a population-based, case-control study with in-person interviews with 373 squamous cell esophageal cancer case patients (124 white males and 249 black males) and 1364 control subjects (750 white males and 614 black males) from three U.S. geographic areas. Histologically confirmed cases of squamous cell esophageal cancer newly diagnosed from August 1, 1986, through April 30, 1989, among white and black men aged 30-79 years were included. RESULTS: Alcohol use of more than one drink per day and/or current cigarette use of at least one pack per day accounted for 92.7% (95% confidence interval [CI] = 86.8%-98.5%) of the squamous cell esophageal cancers in blacks, versus 86.3% (95% CI = 75.5%-97.1%) in whites, and for 94% of the difference between the black and white annual incidence rates. The interaction between race and the continuous drinking/smoking variable in a logistic regression analysis was statistically significant (two-sided, P = .02). Exposure rates among controls at all levels of combined alcohol and tobacco use examined were slightly higher among blacks and accounted for a small portion of the racial differences in incidence rates. CONCLUSION: Although the vast majority of esophageal cancers in both blacks and whites in our data can be explained by use of alcohol and tobacco, it is not clear why heavy consumption of alcohol and/or tobacco is responsible for 14.9 per 100,000 per year more cases of squamous cell esophageal cancer among blacks than among whites. The differences in the odds ratios appear to account for more of the racial differences in incidence rates than do the prevalences of exposure to alcohol and tobacco alone. The reasons for this apparent racial difference in carcinogenic risk from the same level of alcohol and tobacco use are unknown, but they may include qualitative differences in alcohol consumption, differences in other environmental exposures that interact with alcohol and/or tobacco to modify risks, or differences in susceptibility to these factors.

Adenocarcinoma of the esophagus: role of obesity and diet.

BACKGROUND: In the United States, the incidence of adenocarcinoma of the esophagus, including the esophagogastric junction, has been increasing rapidly over the past two decades. Except for an association with Barrett's esophagus, little is known about the etiology of these cancers. PURPOSE: Our purpose was to investigate dietary and nutritional risk factors for adenocarcinoma of the esophagus. METHODS: A population-based, case-control interview study of 174 white men with adenocarcinoma of the esophagus and 750 control subjects living in three areas of the United States was conducted during 1986 through 1989. RESULTS: Risk was significantly elevated for subjects in the heaviest quartile compared with the lightest quartile of body mass index (odds ratio [OR] = 3.1; 95% confidence interval [CI] = 1.8-5.3). No significant associations were seen with total calories from food, number of meals eaten per day, level of fat intake, or consumption of coffee and tea. Risks were highest for those consuming the least amount of vegetables, with some evidence of a dose response for the subcategories of cruciferous vegetables (P for trend < .001) and vegetables consumed raw (P for trend = .10). A significantly elevated risk was also seen for those consuming the least amount of raw fruit (P for trend = .05). No clear associations were reported for intake of particular micronutrients overall or in supplements, but a significant protective effect was associated with increasing intake of dietary fiber (P for trend = .004). CONCLUSIONS: The findings of an increased risk with obesity and decreased risks with intake of raw fruits and vegetables and dietary fiber provide useful directions to pursue in further investigations of this malignancy. IMPLICATIONS: The finding with respect to obesity is particularly noteworthy, since it may explain at least a portion of the recent epidemic increases reported in the incidence of this tumor.

Alcohol dehydrogenase 3 genotype and risk of oral cavity and pharyngeal cancers.

BACKGROUND: The consumption of alcoholic beverages is a strong risk factor for cancers of the oral cavity and pharynx (oral cancers). Alcohol dehydrogenase type 3 (ADH3) metabolizes ethanol to acetaldehyde, a carcinogen. We evaluated whether individuals homozygous for the fast-metabolizing ADH3(1) allele (ADH3[1-1]) have a greater risk of developing oral cancer in the presence of alcoholic beverage consumption than those with the slow-metabolizing ADH3(2) allele (ADH3[1-2] and ADH3[2-2]). METHODS: As part of a population-based study of oral cancer conducted in Puerto Rico, the ADH3 genotypes of 137 patients with histologically confirmed oral cancer and of 146 control subjects (i.e., individuals with no history of oral cancer) were determined by molecular genetic analysis of oral epithelial cell samples. Risks were estimated by use of multiple logistic regression analyses. RESULTS: Compared with nondrinkers with the ADH3(1-1) genotype, consumers of at least 57 alcoholic drinks per week with the ADH3(1-1), ADH3(1-2), and ADH3(2-2) genotypes had 40.1-fold (95% confidence interval [CI] = 5.4-296.0), 7.0-fold (95% CI = 1.4-35.0), and 4.4-fold (95% CI = 0.6-33.0) increased risks of oral cancer, respectively; the risk associated with the ADH3(1-1) genotype, compared with the ADH3(1-2) and ADH3(2-2) genotypes combined, was 5.3 (95% CI = 1.0-28.8) among such drinkers. Considering all levels of alcohol consumption, the risk of oral cancer per additional alcoholic drink per week increased 3.6% (95% CI = 1.9%-5.4%) for subjects with the ADH3(1-1) genotype and 2.0% (95% CI = 0.9%-3.0%) for subjects with the ADH3(1-2) or ADH3(2-2) genotype (two-sided P = .04). CONCLUSIONS: The ADH3(1-1) genotype appears to substantially increase the risk of ethanol-related oral cancer, thus providing further evidence for the carcinogenicity of acetaldehyde.

Dietary and nutritional factors and pancreatic cancer: a case-control study based on direct interviews.

BACKGROUND: The relationship between diet and pancreatic cancer remains unclear. In this study, we assessed the role of diet and nutrition as risk factors for pancreatic cancer, using data obtained from direct interviews only, rather than data from less reliable interviews with next of kin. We evaluated whether dietary factors could explain the higher incidence of pancreatic cancer experienced by black Americans compared with white Americans. METHODS: We conducted a population-based case-control study of pancreatic cancer diagnosed in Atlanta (GA), Detroit (MI), and 10 New Jersey counties from August 1986 through April 1989. Reliable dietary histories were obtained for 436 patients and 2003 general-population control subjects aged 30-79 years. RESULTS: Obesity was associated with a statistically significant 50%-60% increased risk of pancreatic cancer that was consistent by sex and race. Although the magnitude of risk associated with obesity was identical in blacks and whites, a higher percentage of blacks were obese than were whites (women: 38% versus 16%; men: 27% versus 22%). A statistically significant positive trend in risk was observed with increasing caloric intake, with subjects in the highest quartile of caloric intake experiencing a 70% higher risk than those in the lowest quartile. A statistically significant interaction between body mass index (weight in kg/height in m2 for men and weight in kg/height in m1.5 for women) and total caloric intake was observed that was consistent by sex and race. Subjects in the highest quartile of both body mass index and caloric intake had a statistically significant 180% higher risk than those in the lowest quartile. CONCLUSIONS: Obesity is a risk factor for pancreatic cancer and appears to contribute to the higher risk of this disease among blacks than among whites in the United States, particularly among women. Furthermore, the interaction between body mass index and caloric intake suggests the importance of energy balance in pancreatic carcinogenesis.

Prenatal and perinatal risk factors for testicular cancer.

In an attempt to determine the risk factors responsible for the dramatic increases in testicular cancer incidence in young adults, mothers of testicular cancer cases and controls were questioned about in utero exposures, pregnancy-related conditions, and perinatal factors during their pregnancies with the 202 cases and the 206 controls. The strongest risk factor was low birth weight with a greater than 12-fold risk (confidence interval = 2.8 to 78.1) for subjects weighing 5 lb or less at birth compared to those who weighed over 5 lb. A statistically significant 2-fold increase in risk was associated with unusual bleeding or spotting during pregnancy, regardless of whether medication was taken for this condition. Other exposures during pregnancy associated with a statistically significant increase in risk were: use of "sedatives"; alcohol consumption; and exposure to X-rays. No excess risk was associated with the use of hormones during pregnancy. The findings for birth weight and abnormal uterine bleeding suggest that significant compromise of the normal maternal-fetal environment may be associated with subsequent increase in risk of testicular cancer. However, this increase in risk is not great enough to explain the dramatic increases in testicular cancer that have occurred in young adults.

Compensatory lung growth after partial pneumonectomy enhances lung tumorigenesis induced by 3-methylcholanthrene.

In small mammals, partial pneumonectomy (PNX) elicits rapid hyperplastic compensatory growth of the remaining lung parenchyma to restore normal lung mass, structure, and function. In BALB mice subjected to PNX, compensatory lung growth is complete within 10 days. Because cellular hyperplasia contributes to the mechanism of tumor promotion by butylated hydroxytoluene (BHT), we hypothesized that hyperplastic compensatory lung growth would promote tumor formation in carcinogen-treated animals in a manner similar to that observed after BHT. In mice subjected to PNX, within 1 week of treatment with the carcinogen 3-methylcholanthrene (MCA; 10 microg/g body weight), lung tumor multiplicity was 3-7-fold higher in animals subjected to PNX than in mice subjected to a sham operation. The increase in tumor multiplicity occurred when PNX was performed 1, 3, and 6 days before or 1 day after MCA treatment. In the absence of PNX, lung tumor multiplicity in MCA-treated mice given one injection of BHT (200 mg/kg body weight) increased significantly (P < 0.01) as compared to that in mice given MCA alone. Tumor multiplicity continued to increase linearly (R2 = 0.99) with each subsequent BHT injection. Lung tumor multiplicity and tumor size in mice given one or two injections of BHT were comparable to those in animals subjected to PNX. These data demonstrate that post-PNX compensatory lung growth stimulates tumorigenesis in MCA-treated mice and provides a novel model for investigating tumor formation.

Occupational risk factors for laryngeal cancer on the Texas Gulf Coast.

Analyses are reported from a case-control interview study of incident laryngeal cancer on the Gulf Coast of Texas. Study subjects were 183 white men with squamous cell carcinoma of the larynx and 250 frequency matched controls. Occupational exposures were examined controlling for potential confounding by cigarette smoking and alcohol consumption. Significantly elevated risks were seen for men employed in the public services industry [transportation, communication, utilities, sanitary service; relative risk (RR), 1.6]; in metal fabricating (RR, 2.1), construction (RR, 1.7), and maintenance (RR, 2.7) occupations; and for workers potentially exposed to paint (RR, 1.8) and diesel or gasoline fumes (RR, 1.5). Elevated risks of border-line significance were seen for men employed as woodworkers/furniture makers (RR, 8.1) and for those with occupational exposure to asbestos (RR, 1.5). When asbestos was categorized by intensity of exposure, a significant positive gradient was found.

Effect of smoking and alcohol consumption on laryngeal cancer risk in coastal Texas.

Data from case-control studies of respiratory cancer conducted in the Texas Gulf Coast region between 1975 and 1980 were used to examine the effects of smoking and alcohol on laryngeal cancer risk. Analyses were limited to living white males, aged 30-79, which included 151 histologically confirmed incident laryngeal cancer cases and 235 population-based controls. A dose-dependent effect for cigarette smoking was observed, with odds ratios ranging from 4.4 for ever smoking up to one-half pack daily, to 10.4 for smoking more than two packs per day. Risks were strongest for current smokers and declined markedly following smoking cessation. Higher risks were associated with smoking nonfiltered than filtered cigarettes. No significantly elevated risks were associated with the use of other tobacco products. Odds ratios for alcohol beverages did not increase linearly with increasing use; instead risks were twofold for consumption of four or more drinks weekly. Patterns of risk associated with beer and hard liquor were not consistent and few participants drank wine. Although the data were sparse, a dose-response effect for alcohol intake was suggested for tumors of the supraglottis (n = 23), while for nonsupraglottic cases, alcohol risks were elevated but did not increase beyond those observed for four drinks per week. Predicted risks for the combined effects of cigarette and alcohol use were intermediate between an additive and multiplicative form of interaction.

Pesticides and other agricultural risk factors for non-Hodgkin's lymphoma among men in Iowa and Minnesota.

Data from an in-person interview study of 622 white men with newly diagnosed non-Hodgkin's lymphoma and 1245 population-based controls in Iowa and Minnesota were used to measure the risk associated with farming occupation and specific agricultural exposures. Men who ever farmed were at slightly elevated risk of non-Hodgkin's lymphoma (odds ratio = 1.2, 95% confidence interval = 1.0-1.5) that was not linked to specific crops or particular animals. Elevated risks were found, with odds ratio generally 1.5-fold or greater, for personal handling, mixing, or application of several pesticide groups and for individual insecticides, including carbaryl, chlordane, dichlorodiphenyltrichloroethane, diazinon, dichlorvos, lindane, malathion, nicotine, and toxaphene. Associations were generally stronger for first use prior to 1965 than more recently, and when protective clothing or equipment was not used. Small risks were associated with the use of the phenoxyacetic acid herbicide 2,4-dichlorophenoxyacetic acid, but the risks did not increase with latency or failure to use protective equipment. Exposure to numerous pesticides poses problems of interpreting risk associated with a particular chemical, and multiple comparisons increase the chances of false-positive findings. In contrast, nondifferential exposure misclassification due to inaccurate recall can bias risk estimates toward the null and mask positive associations. In the face of these methodological and statistical issues, the consistency of several findings, both within this study and with observations of others, suggests an important role for several insecticides in the etiology of non-Hodgkin's lymphoma among farmers.

Pesticide exposures and other agricultural risk factors for leukemia among men in Iowa and Minnesota.

Mortality surveys and death certificate studies have suggested an association between leukemia and farming. To investigate whether exposure to carcinogens in an agricultural setting is related to risk of leukemia, the authors conducted a population-based case-control interview study of 578 white men with leukemia and 1245 controls living in Iowa and Minnesota. Consistent with recent mortality studies, there were slight, but significant, elevations in risk for all leukemia [odds ratio (OR) 1.2] and chronic lymphocytic leukemia (OR 1.4) for farmers compared to nonfarmers. There were no significant associations with leukemia for exposure to specific fungicides, herbicides (including 2,4-D and 2,4,5-T), or crop insecticides. However, significantly elevated risks for leukemia of greater than or equal to 2.0 were seen for exposure to specific animal insecticides including the organophosphates crotoxyphos (OR 11.1), dichlorvos (OR 2.0), and famphur (OR 2.2) and the natural product pyrethrins (OR 3.7) and the chlorinated hydrocarbon methoxychlor (OR 2.2). There were also smaller, but significant, risks associated with exposure to nicotine (OR 1.6) and DDT (OR 1.3). This finding of elevated risks for insecticides used on animals deserves further evaluation.

Alcohol and pancreatic cancer in blacks and whites in the United States.

A population-based, case-control study of pancreatic cancer based on direct interviews with 307 white and 179 black incident cases and 1164 white and 945 black population controls was conducted in three areas of the United States to determine the role alcohol drinking plays as a risk factor for pancreatic cancer and to estimate the extent to which it may explain the higher incidence of pancreatic cancer in blacks compared to whites. Our findings indicate that alcohol drinking at the levels typically consumed by the general population of the United States is probably not a risk factor for pancreatic cancer. Our data suggest, however, that heavy alcohol drinking may be related to pancreatic cancer risk. Among men, blacks and white who drank at least 57 drinks/week had odds ratios (ORs) of 2.2 [95% confidence interval (CI) = 0.9-5.6] and 1.4 (95% CI = 0.6-3.2), respectively. Among women, blacks who drank 8 to < 21 drinks/week had an OR of 1.8 (95% CI = 0.8-4.0), and those who drank at least 21 drinks/week had an OR of 2.5 (95% CI = 1.02-5.9), but whites with the same levels of alcohol intake experienced no increased risk. Compared to whites, blacks had significantly higher ORs associated with heavy alcohol drinking (> or = 57 drinks/week) in men (P = 0.04) and with moderate-to-heavy drinking (> or = 8 drinks/week) in women (P = 0.03). Additional research is needed to determine whether heavy alcohol drinking is causally related to pancreatic cancer and whether the risk of alcohol-related pancreatic cancer is greater in blacks than in whites.