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Biomedical subjects

S Preston-Martin

Publications and source records attributed to S Preston-Martin.

At least 55 records · Page 3Linked to original sources
PubMed1997

Sinonasal cancer and occupation. Results from the reanalysis of twelve case-control studies.

A pooled reanalysis of twelve case-control studies on sinonasal cancer and occupation from seven countries was conducted in order to study associations with occupations other than wood- and leather-related occupations. The pooled data set included a total of 930 cases (680 men and 250 women) and 3,136 controls (2,349 men and 787 women). All the studies included a detailed occupational history for cases and controls. Each job was coded using the same classifications for occupation and industry. Two approaches were used in the analysis: systematic analysis of occupations; a priori analysis using a preestablished list of occupations and industries. The results confirmed associations observed in several studies not included in this analysis. For agricultural workers, significant excesses were observed for squamous cell carcinoma among women (OR = 1.69) and men (OR = 3.72 for ten years or more of employment as an orchard worker), and adenocarcinomas among men (OR = 2.98 for ten years or more of employment). Associations with textile occupations were observed for adenocarcinoma among women (OR = 2.60) and squamous cell carcinoma among men (OR = 5.09 for fiber preparers, 3.01 for bleachers). Elevated risks for both histologic types were observed among men employed in food manufacturing (OR = 3.25, adenocarcinoma), or as food preservers (OR = 13.9, squamous cell carcinoma), and among men employed as cooks (OR = 1.99, squamous cell carcinoma). A positive association with squamous cell carcinoma was observed for male transport equipment operators (OR = 1.21), and also with adenocarcinoma for male motor-vehicle drivers (OR = 2.50). A number of other associations were observed in the systematic analysis.

Adenocarcinoma↗
PubMed1997

Dietary and other lifestyle factors of women with brain gliomas in Los Angeles County (California, USA)

A population-based interview study in Los Angeles County (California, USA) of 94 women with intracranial gliomas and 94 individually matched neighborhood controls investigated the relationship to various sources of exposure to N-nitroso compounds and their precursors and to vitamins which inhibit the endogenous formation of these compounds. The study offers some support for the hypothesis that dietary sources of nitroso exposure relate to risk. Risk increased with increasing consumption of cured meats, most notably of bacon (odds ratio [OR] for the third tertile of intake = 6.6, 95 percent confidence interval [CI] = 1.9-22.5, P trend < 0.001). Risk was reduced with increasing intake of vegetables such as bell peppers (OR for third tertile = 0.2, CI = 0.1-0.7, P trend < 0.01). In addition, use of vitamin supplements appeared protective, and there was some suggestion that eating cured meats in combination with foods which inhibit endogenous nitrosation mitigates risk. Other potential sources of nitroso exposure such as smoking, cosmetics, and drinking water did not relate to risk. Despite the limitations of data on usual adult diet, it appears that dietary sources of nitroso compounds may be important in the development of gliomas.

Adult↗
PubMed1997

A study of pediatric brain tumors and their association with epilepsy and anticonvulsant use.

OBJECTIVES: To evaluate the risk of childhood brain tumor occurrence in relation to epilepsy and anticonvulsant use. STUDY DESIGN: As part of a multicenter case-control study of pediatric brain tumors, maternal report on epilepsy occurrence before diagnosis of her child's brain tumor was collected for 540 cases and compared with 801 control children. Mothers also reported on any long-term (> or = 2 weeks) use of medications by her child before the date of tumor diagnosis (or a comparable reference date for controls) and these medications were classified according to whether they contained barbiturates. RESULTS: As expected, because seizures are often an early brain tumor symptom, a strong association was observed between epilepsy and brain tumor occurrence (odds ratio, OR = 6.2; 95% confidence limit, CL = 2.9, 14). The association remained elevated even after a > or = 10-year interval between diagnoses of epilepsy and brain tumor (OR = 4.7; CL = 0.8, 48). Elevated odds ratios were observed both for epileptic children who were treated with anticonvulsants containing barbiturates (OR = 5.8; CL = 2.2, 18) and for those not treated with barbiturates (OR = 7.9; CL = 1.7, 74), relative to nonepileptic children. CONCLUSION: Whereas most of the brain tumor risk associated with epilepsy may be due to occult tumors, the finding of an elevated risk many years after diagnosis of epilepsy is of interest.

Adolescent↗
PubMed1997

Household pesticides and risk of pediatric brain tumors.

A follow-up to a population-based case-control study of pediatric brain tumors in Los Angeles County, California, involving mothers of 224 cases and 218 controls, investigated the risk of household pesticide use from pregnancy to diagnosis. Risk was significantly elevated for prenatal exposure to flea/tick pesticides -odds ratio (OR) = 1.7; 95% confidence interval (CI), 1.1-2.6-, particularly among subjects less than 5 years old at diagnosis (OR = 2.5; CI, 1. 2-5.5). Prenatal risk was highest for mothers who prepared, applied, or cleaned up flea/tick products themselves (OR = 2.2; CI, 1.1-4.2; for subjects <5 years of age, OR = 5.4; CI, 1.3-22.3). A significant trend of increased risk with increased exposure was observed for number of pets treated (p = 0.04). Multivariate analysis of types of flea/tick products indicated that sprays/foggers were the only products significantly related to risk (OR =10.8; CI, 1.3-89.1). Elevated risks were not observed for termite or lice treatments, pesticides for nuisance pests, or yard and garden insecticides, herbicides, fungicides, or snail killer. Certain precautions,if ignored, were associated with significant increased risk: evacuating the house after spraying or dusting for pests (OR = 1.6; CI, 1.0-2.6), delaying the harvest of food after pesticide treatment (OR = 3.6; CI, 1.0-13.7), and following instructions on pesticide labels (OR = 3. 7;CI, 1.5-9.6). These findings indicate that chemicals used in flea/tick products may increase risk of pediatric brain tumors and suggest that further research be done to pinpoint specific chemicals involved.

Adolescent↗
PubMed1997

Ras oncogene mutations in childhood brain tumors.

Although N-nitroso compounds (NNC) are ubiquitous in the human environment and are known neurocarcinogens in animal models, results of epidemiological studies have not yet convincingly associated NNCs with brain tumor occurrence in humans. Animal studies have suggested that specific codons (12, 13, and 61) in the ras family are mutable by exposure to NNCs. The purpose of this study was to measure the presence of mutations in the ras family of oncogenes in tissue from childhood brain (CB) tumors as a preliminary step toward investigating their potential use as biomarkers of chemical exposure. DNA was extracted from paraffin-embedded formalin-fixed CB tumors from tissues resected during neurosurgical operations. Using the PCR, designed RFLP-screening methods, and sequencing, we attempted to screen brain tumors from 46 children for the presence of H, K, and N-ras mutations at codons 12, 13, and 61. Screening for oncogene mutations using PCR, RFLP methods, and DNA sequencing was successfully completed for a high proportion of the available specimens. Astrocytoma specimens from three children for whom screening with PCR was successfully completed were found to contain CAA-->GAA point mutations in K-ras at codon 61. None of the specimens contained mutations at any of the other locations. These results, although preliminary, provide a potential clue for future mechanistic studies of CB tumors. The possible roles of NNCs in inducing this mutation, or of this mutation as an early or late event in tumor progression, however, remain unclear.

Adolescent↗
PubMed1996

Brain tumor risk in children in relation to use of electric blankets and water bed heaters. Results from the United States West Coast Childhood Brain Tumor Study.

The possible relation between the occurrence of brain tumors in children and exposure to electric blankets or electrically heated water beds was investigated in a multicenter, population-based case-control study conducted on the West Coast of the United States. Information on maternal exposure during pregnancy or direct exposure to the subject child was collected by in-person interview from the mothers of 540 case children and 801 control children. Cases were 19 years of age or younger and were diagnosed between 1984 and 1991. Controls were recruited using a random digit dialing procedure. The risk of brain tumor occurrence from in utero exposure to either electric blankets (odds ratio (OR) = 0.9, 95% confidence interval (Cl) 0.6-1.2) or heated water beds (OR = 0.9, 95% Cl 0.6-1.3) was not elevated. Brain cancer risk did not vary by use in any trimester of pregnancy, and children with mothers who reported use throughout their pregnancy had no increased risk. Similar results were observed for exposure to the child, in that no association between brain cancer and use of electric blankets (OR = 1.0, 95% Cl 0.6-1.7) or heated water beds (OR = 1.2, 95% Cl 0.7-2.0) was observed. Risks did not vary significantly by age, sex, race, socioeconomic status, or histologic category for either in utero exposure or child's exposure. This study provides no evidence to support the hypothesis that there is a relation between brain cancer occurrence in children and 50-/60-Hz magnetic field exposure from the use of electric blankets and heated water beds.

Adolescent↗
PubMed1996

Los Angeles study of residential magnetic fields and childhood brain tumors.

A measurement study of residential magnetic fields and brain tumors in children that was added onto an ongoing case-control interview study in Los Angeles County, California, include 298 children under age 20 years with a primary brain tumor diagnosed from 1984 to 1991 and 298 control children identified by random digit dialing. Magnetic fields were determined for all Los Angeles homes where these 596 children lived from conception to diagnosis (1,131 homes) by mapping and coding the wiring configurations outside the home and by taking a series of exterior spot and profile measurements. In addition, for a subset of subjects (35%; 211 homes) 24-hour measurements were taken in the child's room and one other room. Although measured fields are consistently highest in the highest of the five wire code categories, fields in homes in this category are much lower in Los Angeles than in Denver, where the code originated. Brain tumor risk appears not to relate to measured fields inside (p for trend for child's room = 0.98) or outside (p for trend for front wall = 0.82) the home. An apparent increase in risk among children living at diagnosis in homes with underground wiring appears to be an artifact introduced by using current controls for historical cases because this apparent excess risk disappeared in an analysis restricted to the later years of the study when cases and controls were accrued concurrently. Our study does not show an overall association of pediatric brain tumors with measured fields, with "very high" wiring configurations, or with any of several other potential sources of exposure, such as use of various electrical appliances, but the prevalence of high fields (> 2 mG) and very high fields (> 3 mG) in Los Angeles homes was too low to detect a moderate effect of the magnitude reported in other studies.

Adolescent↗
PubMed1996

High frequency of acute promyelocytic leukemia among Latinos with acute myeloid leukemia.

A high frequency (24%) of acute promyelocytic leukemia (APL) was noted among acute myelocytic leukemia (AML) cases at the Los Angeles County-University of Southern California (LAC-USC) Medical Center, in comparison with the expected frequency of 5% to 15%. Because of the high proportion of Latinos in this center, we questioned if APL is more common in this ethnic group. The proportion of APL among the 80 AML patients of Latino origin was significantly higher (30; 37.5%) when compared with the 62 non-Latinos (4; 6.5%) (P = .00001). In an attempt to verify this finding on a larger group of patients, we analyzed 276 pathologically verified cases of AML in patients aged 30 to 69 years from the entire County of Los Angeles, registered on an ongoing population-based epidemiologic study of AML. APL was more frequent among the 47 Latinos (24.3%) than in the 229 non-Latinos (8.3%) (P = .0075). APL is seen in younger patients with AML, but Latino AML patients also had a higher frequency of APL after accounting for their younger age (age-adjusted odds ratio for APL among Latinos in LAC-USC Medical Center, 9.4 [95% confidence interval (CI) 2.9, 30] P = .0002; among Latinos in the population-based study, 3.0 [95% CI 1.3 to 6.9] P = .01). The different ethnic distribution of AML was found to be due to a higher proportion of APL cases per se, and not to a lower proportion of any other French-American-British subtype (P = .0004). These results, from two different populations of AML patients, indicate that Latinos with AML have a higher likelihood of the APL subtype of disease, which may suggest a genetic predisposition to APL and/or exposure to distinct environmental factor(s).

Adolescent↗
PubMed1996

Solar radiation, lip protection, and lip cancer risk in Los Angeles County women (California, United States).

A population-based case-control study of 74 women with lip cancer diagnosed from 1978 to 1985 in Los Angeles County (California, United States) and frequency matched to 105 controls investigated the risk of solar radiation and protection from lip sunscreening agents to explore the hypothesis that excess incidence of lip cancer seen in men is due partly to lower rates in women, conferred by frequent use of lip protection. We confirm the importance in women of risk factors similar to those found in men, i.e., fair complexion, sun exposure, and smoking. Risk was related strongly to lifetime solar radiation (odds ratio [OR] = 13.5 for highest quartile of exposure, 95 percent confidence interval [CI] = 4.5-40.6, P trend < 0.0001) and time spent outdoors (OR = 4.7 for highest quartile of average yearly hours, CI = 1.9-12.1, P trend = 0.01). Further, among women with high lifetime solar-radiation exposure, those who used lip protection once a day or less had twice the risk of lip cancer than women who used lip protection more than once a day (OR = 7.3, CI = 1.9-27.2 cf OR = 3.2, CI = 1.1-9.2). These findings show that solar radiation is a major risk factor for lip cancer and suggest that lip sunscreening is protective, thereby supporting the hypothesis that use of lipstick and other sunscreening agents by women has contributed to their lower incidence of this disease.

Adult↗
PubMed1996

Sexual, reproductive, and other risk factors for adenocarcinoma of the cervix: results from a population-based case-control study (California, United States)

The incidence of adenocarcinoma of the cervix increased steadily in young women in the United States between the early 1970s and the mid-1980s. Despite this increase, little is known about the etiology of this cancer, although a role for risk factors for both squamous cell carcinoma of the cervix and endometrial adenocarcinoma has been suggested. Incident cases of adenocarcinoma of the cervix diagnosed in women born after 1935 (ages 42 to 56 at diagnosis) were identified from the Los Angeles (California) County Cancer Surveillance Program (LACCSP). Data from personal interviews with 195 cases and 386 controls (matched on age, race, and neighborhood) were analyzed. Compared with women in the highest categories of education and income, women in the lowest categories had a 2.5 and 3.1-fold elevated risk of adenocarcinoma of the cervix. Number of sexual partners, especially before age 20, was strongly predictive of risk (odds ratio = 5.6, 95 percent confidence interval = 1.4-22.0 for 10 or more compared with no partners before age 20). Smoking was not associated significantly with risk. Weight gain and long-term use of oral contraceptives increased risk, while long-term diaphragm use was protective. This study suggests that both sexual and hormonal factors are important etiologic factors for adenocarcinoma of the cervix.

Adenocarcinoma↗
PubMed1996

Epidemiology of primary CNS neoplasms.

Heritable syndromes and ionizing radiation, the only two established causes of primary CNS tumors, each account for only a few percent of cases of this disease. Findings are inconclusive for other suggested risk factors, including head trauma, prior infections, and pesticides, among others. The apparent secular increase in brain tumor rates is most likely predominantly attributable to improvements in diagnosis. The differing patterns of occurrence of gliomas and meningiomas suggest the need for separate study. Future studies should aim for more precise assessment of environmental exposure and simultaneous consideration of individual susceptibility.

Adolescent↗
PubMed1996

Assessment of cellular telephone and other radio frequency exposure for epidemiologic research.

Epidemiologists are now embarking on the evaluation of the hypothesis that exposure to radio frequency energy from low-power wireless communication devices, such as portable cellular telephones, causes brain cancer and other adverse health outcomes. Even in the laboratory, exposures from radio frequency sources are difficult to quantify; their measurement in large populations for epidemiologic study is challenging. In this paper, we outline the nature and magnitude of these exposures and discuss the prospects for obtaining useful measures of exposure for epidemiologic research.

Brain Neoplasms↗
PubMed1996

Maternal consumption of cured meats and vitamins in relation to pediatric brain tumors.

Brain tumors are the leading cause of death from childhood cancer, yet the causes of most of these tumors remain obscure. Few chemicals are effective in causing brain tumors experimentally after systemic administration of low doses; a notable exception is one group of N-nitroso compounds, the nitrosamides (in particular the nitrosoureas). Feeding pregnant animals nitrosamide precursors (e.g., sodium nitrite and an alkylamide such as ethylurea) causes a high incidence of nervous system tumors in offspring. This population-based epidemiological study was designed to test the hypothesis that maternal consumption during pregnancy of meats cured with sodium nitrite increases the risk of brain tumors among offspring. The intake of vitamins C and E blocks endogenous formation of nitroso compounds and was expected to be protective. Mothers of 540 children under age 20 with a primary brain tumor diagnosed during 1984-1991 and 801 control children in the same 19 counties on the U.S. West Coast were interviewed. Risk increased with increasing frequency of eating processed meats [odds ratio (OR) = 2.1 for eating at least twice a day compared to not eating; 95% confidence interval (CI) = 1.3-3.2; P = 0.003). Risk also increased with increasing average daily grams of cured meats or mg of nitrite from cured meats (P for each <0.005) but not with nitrate from vegetables. Daily use of prenatal vitamins throughout the pregnancy decreased risk (OR = 0.54; CI = 0.39-0.75). Risk among mothers who consumed above the median level of nitrite from cured meat was greater if vitamins were not taken (OR = 2.4; CI = 1.4-3.6) than if they were (OR = 1.3). These effects were evident for each of three major histological types and across social classes, age groups, and geographic areas. This largest study to date of maternal diet and childhood brain tumors suggests that exposure during gestation to endogenously formed nitroso compounds may be associated with tumor occurrence. Laboratory exploration is needed to: (a) define dietary sources of exposure to alkylamides; (b) investigate the reactivity of nitrite in high concentration such as around bits of cured meats in the stomach after ingestion compared to nitrite in dilute solution; and (c) confirm that simultaneous ingestion of alkylamides and cured meats leads to the endogenous formation of nitrosamides.

Adolescent↗
PubMed1996

Childhood brain tumors and exposure to tobacco smoke.

Brain tumors are the second most common cancer in children after leukemia, yet the etiology of childhood brain tumors remains unknown. Tobacco smoke contains several dozen compounds that are known to be carcinogens. Among these are N-nitroso compound precursors, principally tobacco-specific nitrosamines. Although smoking has not been identified as a significant risk factor for the development of brain tumors in adults, fetuses and infants have incompletely formed blood-brain barriers that may allow the passage of carcinogenic tobacco metabolites into the central nervous system and initiate the formation of neural tumors. In this review, we present data from case-control and cohort studies published between 1971 and 1995 that examined the relationship between parental smoking during pregnancy and childhood brain tumors (CBTs). The majority of these studies found little association between CBTs and maternal smoking before or during pregnancy or between CBTs and maternal exposure to passive smoke during pregnancy.

Blood-Brain Barrier↗
PubMed1996

Prenatal exposure to tobacco smoke and childhood brain tumors: results from the United States West Coast childhood brain tumor study.

Data from a large, population-based case-control study were analyzed to investigate the relationship between prenatal exposure to tobacco smoke and childhood brain tumors (CBTs). A total of 540 CBT patients, diagnosed between 1984 and 1991, were identified from population-based tumor registries in 19 West Coast counties that included Seattle, WA (13 counties), San Francisco, CA (5 counties), and Los Angeles, CA (1 county). Random digit dial was used to select 801 control subjects from the three geographical regions to obtain a case:control ratio of 1:2 in San Francisco and Seattle and 1:1 in Los Angeles. The data first were analyzed separately by geographical site and then were combined with adjustments made for gender, age at the time of diagnosis (or reference date of control subjects), birth year of the index child, and maternal race. No association was found between the risk of CBTs and maternal or paternal smoking before pregnancy and there was no association between CBTs and maternal smoking during pregnancy [odds ratio (OR) = 0.98; 95% confidence interval (CI) = 0.72-1.3]. A slightly increased OR for CBTs was found for paternal smoking during pregnancy in the absence of maternal smoking (OR = 1.2; 95% CI = 0.90-1.5) and for maternal exposure to passive smoke from any source (OR = 1.2; 95% CI = 0.95-1.6). The results of this analysis are consistent with results from several prior epidemiological studies that showed no significant association between CBTs and maternal smoking before or during pregnancy or maternal exposure to passive smoke during pregnancy.

Adolescent↗