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Biomedical subjects

J M Samet

Publications and source records attributed to J M Samet.

At least 127 records · Page 7Linked to original sources
PubMed1994

Breast cancer among Hispanics, American Indians and non-Hispanic whites in New Mexico.

Variation in breast cancer occurrence among women in New Mexico's three major ethnic groups has not previously been assessed. The address the descriptive epidemiology of breast cancer in New Mexico Hispanics, American Indians, and non-Hispanic whites, we calculated incidence rates from population-based registry data covering 1969-1987 and mortality data collected from 1958 to 1987. Breast cancer incidence and mortality rates for New Mexico's non-Hispanic white women were comparable to those for white women nationwide. In contrast, American Indian women had extremely low incidence and mortality rates for breast cancer; rates for Hispanics were intermediate, but well below those for non-Hispanic white women throughout the study period. Pronounced temporal trends in breast cancer occurrence were evident among Hispanic women, with the incidence rate increasing by 56% over the 19 years of available data and the mortality rate increasing by nearly 100% over 30 years. Age-specific incidence and mortality rates increased at all ages for successive birth cohorts of Hispanic women. For non-Hispanic whites, increasing incidence and mortality rates were also observed, but the increments were much smaller, approximately 15% for incidence and 30% for mortality. Our data show substantial ethnic differences in breast cancer incidence and mortality in New Mexico, suggesting the need for aetiological investigations to assist in controlling this disease.

Adult↗
PubMed1994

Silicosis and lung cancer risk in underground uranium miners.

The presence of radiographic silicosis as a risk factor for lung cancer was assessed in a case-control study conducted within a study cohort of New Mexico underground uranium miners. Chest radiographs were interpreted for the presence of silicosis for 65 lung cancer cases and 216 controls. The presence of silicosis on the chest radiograph taken closest to the start of employment or on the latest radiograph available was not associated with lung cancer risk after adjustment for cumulative exposure to radon progeny. The odds ratio associated with the presence of any type of opacity indicative of pneumoconiosis on the chest x ray closest to the start of employment was 1.33 (95% confidence interval, 0.31-5.72). For the most recent available chest x ray, the corresponding odds ratio was 1.16 (95% confidence interval, 0.35-3.84). Although the findings are limited by the relatively small number of subjects, the lack of association of silicosis with lung cancer suggests that silica exposure should not be regarded as a major uncertainty in extrapolating radon risk estimates from miners to the general population.

Case-Control Studies↗
PubMed1994

The role of airway mucus in pulmonary toxicology.

Airway mucus is a complex airway secretion whose primary function as part of the mucociliary transport mechanism is to to serve as renewable and transportable barrier against inhaled particulates and toxic agents. The rheologic properties necessary for this function are imparted by glycoproteins, or mucins. Some respiratory disease states, e.g., asthma, cystic fibrosis, and bronchitis, are characterized by quantitative and qualitative changes in mucus biosynthesis that contribute to pulmonary pathology. Similar alterations in various aspects of mucin biochemistry and biophysics, leading to mucus hypersecretion and altered mucus rheology, result from inhalation of certain air pollutants, such as ozone, sulfur dioxide, nitrogen dioxide, and cigarette smoke. The consequences of these pollutant-induced alterations in mucus biology are discussed in the context of pulmonary pathophysiology and toxicology.

Air Pollutants↗
PubMed1994

Risk assessment of oxidant gases and particulate air pollutants: uncertainties and research needs.

The assessment of risks to human health associated with exposure to oxidant air pollutants has not received adequate attention despite the recognized public health threat posed by the ubiquitous presence of these compounds in the environment. In this article, research needs and uncertainties at each of the steps in the risk assessment of oxidant air pollutants are identified: hazard identification, dose-response assessment, exposure assessment, and risk characterization. Many of these limitations and uncertainties arise at the interface between the laboratory and the regulatory arenas. Therefore, as a case study, relevant methodologic problems associated with the application of experimental findings to the risk assessment of respirable dusts are also discussed. These issues include the extrapolation of animal data to the human case and extrapolation from high-dose to environmentally relevant, low-level exposures.

Air Pollutants↗
PubMed1994

Lung cancer.

During the 20th century, a dramatic epidemic of lung cancer deaths has occurred in many countries. The time trends of lung cancer incidence and mortality primarily reflect patterns of cigarette smoking, the predominant risk factor, but inconsistencies are evident in international comparisons. Although the predominant role of tobacco smoking as a cause of lung cancer throughout the world is amply documented, the persistence of tobacco smoking and the continued penetration of manufactured cigarettes into new markets provide a strong reason for continuing to monitor lung cancer trends. Changes in other risk factors for lung cancer and changes in diagnostic and death certificate reporting practices may also affect trends in rates. However, our understanding of the relationship between smoking and lung cancer allows forecasting of lung cancer rates for public health planning.

Adult↗
PubMed1994

Nitrogen dioxide and respiratory illness in children. Part III: Quality assurance in an epidemiologic study.

This report describes the quality assurance and quality control program developed for the previously reported epidemiologic study of nitrogen dioxide (NO2) and respiratory illness in children (Health Effects Institute Research Report 58, Parts I and II). The specific aims of the program were to make certain that data were sufficiently accurate, complete, verifiable, and retrievable. The quality assurance and quality control program consisted of: a written protocol, standard operating procedures, written records, a project management system, appropriate data processing, data verification, and data analysis planning, and was staffed by qualified and appropriately trained personnel. Within the activities of the overall program, two focused quality assurance studies were conducted. During the first of these focused studies, parents maintained a calendar-diary of their child's daily respiratory symptoms. Telephone interviews were conducted at intervals of two weeks, and parents used the calendars to report on symptom occurrence since the previous call. To assess the comparability of illness events based on symptom reports from the parents with usual clinical diagnostic methods, nurse practitioners examined children during illness, and office and clinic records of outpatient visits were reviewed. Using the parent reports, respiratory illnesses were defined as symptom episodes of at least two consecutive days; lower respiratory illnesses included at least one day of either wet cough or wheeze. Runny or stuffy nose was reported for 93% of illnesses; and wet cough for 33% and wheeze for 6% of illnesses. In comparison with the diagnoses made by a nurse practitioner, parent reports of wet cough or wheeze were sensitive (93.4%) for detecting lower respiratory illnesses, but nonspecific (with specificity of only 24.2%). The majority of the false-positive lower respiratory illnesses had the symptom of wet cough. The comparison of parent reports with outpatient records provided similar findings. These findings indicate that standardized reporting of respiratory illnesses can be achieved with regular telephone interviews, but the classification of specific illnesses from the observations of parents' information may differ from diagnoses made by clinicians. The second focused quality assurance study evaluated the measurement error associated with the parents' use of passive diffusion samplers for NO2. Midway through the study, technicians conducted home visits to assess compliance with stated procedures, and to make independent measurements of NO2. Based on criteria for placement and use of the samplers, conditions of noncompliance were observed on about 40% of visits.(ABSTRACT TRUNCATED AT 400 WORDS)

Data Collection↗
PubMed1994

Trends in prostate cancer incidence and mortality in New Mexico are consistent with an increase in effective screening.

The increasing occurrence of prostate cancer in the United States has led to recommendations for routine prostate cancer screening in men aged 50 years and older. Although present methods of prostate cancer screening have not been shown to reduce mortality, screening using digital rectal examination or prostate-specific antigen does detect tumors at earlier stages. To assess whether trends in incidence and mortality rates are consistent with an increase in effective screening in New Mexico, we examined prostate cancer incidence rates calculated from data collected by the New Mexico Tumor Registry for the years 1969-1991, and mortality rates calculated from data collected by the New Mexico Bureau of Vital Statistics for the years 1958-1991. Population-based measures of prostate cancer screening frequency in New Mexico are not available for the period of this study; however, the proportion of prostate cancers detected by screening, as documented by a review of records from a random sample of prostate cancer cases, increased 3-fold, from 13% during the 1969-1972 period to 41% in the 1988-1991 period. During the period of study, age-adjusted incidence rates increased from 66.3 to 122.3/100,000 men. Stage migration from distant to earlier stages was apparent in the increase in the proportion of early stage cancers from 77.5 to 85.5%, and the decrease of distant stage cancers from 21.2 to 9.8%. Stage-specific incidence rates increased for local (87.3%) and regional stage cancers (283.0%), and decreased for distant stage cancers (16.0%).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Cancer mortality among New Mexico's Hispanics, American Indians, and non-Hispanic Whites, 1958-1987.

BACKGROUND: Racial and ethnic differences in cancer incidence and mortality are well documented. New Mexico's ethnically and racially diverse population provides an opportunity to further examine ethnic and racial differences in cancer occurrence. PURPOSE: To address differences in cancer mortality among the state's Hispanics, American Indians, and non-Hispanic Whites, we examined mortality data collected from 1958 through 1987. METHODS: Sex and age-specific and age-adjusted cancer mortality rates were calculated for all sites and specific sites for American Indians, Hispanics, and non-Hispanic Whites. From 1958 through 1987, deaths due to malignant neoplasms were coded according to the International Classification of Diseases. The categories of malignant neoplasms investigated were chosen, in part, to minimize bias due to changes in disease classification. Ethnicity was assigned by the Bureau of Vital Statistics on the basis of information on death certificates. Denominators were derived from the censuses of 1960, 1970, 1980, and 1990. Age-standardized mortality rates were calculated for 5-year periods (1958-1962, 1963-1967, 1968-1972, 1973-1977, 1978-1982, and 1983-1987), with the 1970 U.S. population as the standard. We also examined age-specific rates by time period. RESULTS: Within each of New Mexico's ethnic groups, overall cancer mortality increased over the 30-year time span, and the cancer mortality rates were greater for males than for females. For most major cancer sites, mortality rates for New Mexico's non-Hispanic Whites were comparable with data for U.S. Whites. American Indians had the lowest rates for most sites, whereas cancer mortality rates for most sites among Hispanics were intermediate between the two other groups. However, Hispanics and American Indians had higher mortality rates for cancers of the gallbladder, cervix, and stomach compared with non-Hispanic Whites throughout most of the study period. Several other cancer sites showed major mortality rate differences among these racial and ethnic groups, including cancers of the colon, rectum, breast, bladder, lung, ovary, and uterus. We also observed strong temporal trends of increasing or decreasing mortality rates for several cancer sites. CONCLUSIONS: Race and ethnicity have been strong determinants of cancer mortality in New Mexico. Within the span of one generation, cancer mortality has changed substantially for some cancer sites in each of the population groups studied. IMPLICATIONS: These mortality data underscore the need for appropriately designed etiologic studies of cancer in diverse racial and ethnic groups. Such etiologic studies could provide new insights concerning risk factors for cancer and useful data for developing race- and ethnic-specific cancer control strategies.

Adult↗
PubMed1993

p53 protein accumulates frequently in early bronchial neoplasia.

p53 mutations are common in human lung cancer and frequently generate levels of p53 protein that are detectable by immunohistochemistry. For this reason, p53 protein accumulation is a candidate biomarker, but little is known about its timing or frequency in multistage bronchial carcinogenesis. We studied human lung tissues containing preinvasive squamous neoplasms from 34 donors with and without lung cancer. Nuclear p53 protein was present in 0% of normal mucosas, 6.7% of squamous metaplasias, 29.5% of mild dysplasias, 26.9% of moderate dysplasias, 59.7% of severe dysplasias, 58.5% of carcinomas in situ, 67.5% of microinvasive carcinomas, and 79.5% of invasive tumors. These data indicate that (a) p53 protein accumulates in about 30% of the earliest recognized neoplastic lesions (i.e., mild dysplasia), (b) there is an increasing frequency of p53 protein accumulation starting with mild dysplasia, and (c) p53 protein accumulates infrequently in normal or metaplastic mucosa. In a subset of six patients whose most advanced lesion was carcinoma in situ without evidence of invasive cancer, p53 protein was detected in 0% of normal mucosas, 8.3% of squamous metaplasias, 37.5% of mild dysplasias, 12.5% of moderate dysplasias, 93.8% of severe dysplasias, and 55% of carcinoma in situ lesions. These data show clearly that p53 alterations can occur before invasion and suggest that the frequency is similar to that observed in the full series. Since two-thirds or more of lung cancers have p53 alterations, the timing and frequency of p53 protein accumulation make the p53 tumor suppressor gene an attractive marker for early diagnosis and evaluation of chemoprevention agents.

Biomarkers, Tumor↗
PubMed1993

Determinants of cancer therapy in elderly patients.

BACKGROUND: Older patients with cancer are less likely to receive definitive therapy, but the reasons for this are unclear. METHODS: All people aged 65 years or older living in six counties in New Mexico and diagnosed with breast, prostate, or colorectal cancer between May 15, 1984 and May 15, 1986 (N = 669) were interviewed to obtain information on demographics, socioeconomic status, functional status, social support, other medical conditions, and cognitive status. Cancer treatment information was obtained from the New Mexico Tumor Registry. RESULTS: In univariate analyses, the following variables were associated significantly with nonreceipt of definitive therapy for cancer: advanced age, impairment in activities of daily living, low physical activity, decreased mental status, impaired access to transportation, and poor social support. In a multivariate analysis with the above variables along with measures of comorbidity, only advanced age and decreased mental status remained significant predictors of nonreceipt of definitive surgery, whereas the effects of impaired access to transportation and low physical activity remained relatively large but no longer were statistically significant. When receipt of surgery and receipt of radiation therapy were considered separately, older age, limited access to transportation, impaired functional status, and impaired mental status all significantly predicted nonreceipt of radiation therapy, but not surgery. CONCLUSIONS: There is a decline with age in the percentage of adults with cancer who received definitive therapy independent of other potentially explanatory factors such as comorbidity. In addition, decisions about radiation may be influenced by nonmedical, potentially correctable factors such as impaired access to transportation.

Activities of Daily Living↗
PubMed1993

Respiratory and irritant health effects of ambient volatile organic compounds. The Kanawha County Health Study.

Kanawha County, West Virginia, is one of the largest chemical manufacturing centers in the United States. In 1988, a survey of respiratory and irritant symptoms was administered to all third grade to fifth grade children attending 74 elementary schools in Kanawha County, and concentrations of 15 volatile organic compounds were measured at each school. Exposures were characterized by school location, by the sum of the concentrations of five petroleum-related compounds, and by the sum of the concentrations of 10 compounds more specific to industrial processes. Children enrolled in schools within the valley had higher rates of doctor-diagnosed asthma (odds ratio (OR) = 1.27, 95% confidence interval (CI) 1.09-1.48) and a higher score on a composite indicator of five chronic lower respiratory symptoms (OR = 1.13, 95% CI 1.02-1.26) than children who were enrolled in schools outside of the valley. The incidence of chronic respiratory symptoms was also positively associated with the concentrations of volatile organic compounds. The estimated change in the odds ratio for chronic lower respiratory symptoms associated with a 2-micrograms/m3 change in process-related compounds was 1.08 (95% CI 1.02-1.14). No consistent pattern was found between acute irritant symptoms in the 2 weeks preceding questionnaire administration and either proximity to industry or exposure to volatile organic compounds. The authors conclude that exposure to volatile organic compounds, including emissions from chemical manufacturing plants, is associated with increased rates of chronic respiratory symptoms characteristic of reactive airways.

Air Pollutants↗
PubMed1993

A review of ecologic studies of lung cancer and indoor radon.

Although radon exposure is an established cause of lung cancer among underground miners, the lung cancer risk to the general population from indoor radon remains controversial. This controversy stems in part from the contradictory results of published studies of indoor radon and lung cancer, including 15 ecologic studies, seven of which found a positive association, six no association, and two a negative association. To address the misunderstanding of the indoor radon risk that has resulted from these ecologic studies, the authors discuss the general methodologic problems and limitations of ecologic studies, and the particular limitations of these 15 studies. The authors conclude that the shortcomings of the ecologic studies render them uninformative on the lung cancer risk associated with indoor radon.

Air Pollutants, Radioactive↗
PubMed1993

Use of chest radiographs in epidemiological investigations of pneumoconioses.

The International Labour Organisation (ILO) classification of radiographs of pneumoconioses was developed to limit variation in classification of parenchymal abnormalities. In this study the manner in which chest radiographs were interpreted in 134 investigations reported in four peer reviewed journals during the five year period 1985-90 was examined. The approach for applying the ILO system was poorly described in most studies. For example, of 86 investigations using more than one reader, 66.3% described the method of reconciliation, but methods were not consistent among investigations. Our results indicate a number of potential problems in application of the ILO system, and gaps in existing recommendations that should be considered.

Decision Making↗