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G M Swanson

Publications and source records attributed to G M Swanson.

At least 55 records · Page 3Linked to original sources
PubMed1996

Nasopharyngeal cancer in a low-risk population: defining risk factors by histological type.

Nasopharyngeal cancer (NPC) is a major public health problem in parts of Southeast Asia and North Africa, but is rare among whites and blacks. Although infection with the EBV and genetic susceptibility appear to play large roles in high-incidence populations, migrant studies suggest that environmental factors may also be important. Aside from the high risks associated with ingestion of salted fish, surprisingly few other risk factors have been established from studies in endemic areas. We studied a low-incidence population to determine whether tobacco use, alcohol consumption, and certain medical conditions and treatments are related to NPC and to examine variations in risk by histology. We reasoned that new relationships might be best identified in the absence of strong causal pathways, such as intake of preserved foods and genetic susceptibility. A population-based case-control study was conducted from 1987 to 1993 at five cancer registries in the United States: western Washington, metropolitan Detroit, Connecticut, Iowa, and Utah. Controls were identified by random digit dialing and frequency matched to the gender and age distribution of cases at each registry. Telephone interviews were completed by 231 cases and 246 controls. We observed a strong dose-response relationship between cigarette smoking and risk of differentiated squamous cell carcinoma (test for trend, P < .001). The highest risk [odds ratio (OR), 6.5; 95% confidence interval (CI), 2.0-21.3] occurred among current smokers with a history of more than 60 pack-years. In contrast, there was no evidence that undifferentiated or nonkeratinizing carcinomas were associated with cigarette smoking. Similarly, a significant increase in risk was observed for the heaviest alcohol consumers (21 or more drinks/week) only for differentiated squamous cell carcinomas (OR, 2.9; 95% CI, 1.2-6.9). The associations with cigarettes and alcohol appeared to be stronger among persons 50 years or older. There was a suggestion that diagnosis with infectious mononucleosis (a marker of late infection with EBV) is linked with decreased NPC risk (OR, 0.4; 95% CI, 0.1-1.1). This report indicates that over two-thirds of differentiated squamous cell NPC cases arising in older persons in the United States can be accounted for by cigarettes and alcohol, but leaves unexplained cases arising in the young and carcinomas of undifferentiated or nonkeratinizing histology. Future studies of NPC need to take into account histology and age in evaluating these and other environmental and genetic risk factors.

Adult↗
PubMed1996

Associations between human leukocyte antigen type and nasopharyngeal carcinoma in Caucasians in the United States.

A genetic component to nasopharyngeal carcinoma (NPC) has been suggested by associations of the malignancy with human leukocyte antigens (HLAs) in Southern Chinese populations, among which NPC is a major cancer. Data from other races are inconclusive. We have investigated associations between NPC and HLA antigens at the HLA-A, B, C, and DQ loci and alleles at the DRB1 locus in a population-based, multicenter investigation in the United States. Data from 82 cases and 140 controls are presented, making this the largest study population analyzing data from Caucasians to date. HLA frequencies from study cases were also compared with external control groups from the 11th International Histocompatibility Workshop and the National Marrow Donor Program. Logistic regression methods were used to investigate the effects of the joint occurrence of multiple HLA types and to assay for differences in HLA-associated risk in different age groups. A meta-analysis was undertaken to compare and summarize our results with previously published findings. The meta-analysis found a protective association with A2 antigen in non-Chinese [odds ratio (OR), 0.63; P < 0.001], a protective association with A11 across all races (OR, 0.54; P < 0.001), and an increased risk associated with B5 in Caucasians (OR, 2.81; P < 0.001). The present study also found independent associations, in a logistic regression model, between NPC and DRB1*1501 (OR, 0.33), DRB1*0405 (OR, 7.57), and Cw3 (OR, 0.42), although these data must be interpreted cautiously due to multiple-testing considerations. Associations were found to be more pronounced in younger patients for A2, A11, A28, B8, and B51.

Adult↗
PubMed1995

Recruiting minorities into clinical trials: toward a participant-friendly system.

The purpose of this review is to describe the state of the art in recruiting participants for clinical trials designed to test new methods of treatment or disease prevention. The ultimate objective of this review is to provide a summary of key issues in recruiting diverse populations into clinical trials, particularly ethnic and racial minorities. An overview of general issues related to clinical trial participation is followed by a detailed discussion of specific issues that must be addressed by investigators as they recruit minority populations for clinical trial. To date, the majority of clinical trials have included a limited segment of the U.S. population: middle-class, married white males. These trials have faced many problems in their efforts to recruit participants, including barriers to physician participation, barriers to subject participation, barriers to planning and implementing effective recruitment strategies, and costs of the recruitment phase of clinical trials. Following this general introduction is a discussion of the definition of diverse populations. The first step investigators must take as they prepare to recruit study participants is to develop a relevant definition of the subject populations. A detailed review of investigators' experiences in recruiting minorities into clinical trials is presented, including barriers to minority recruitment, barriers inherent in study design, researcher bias, barriers to minority physician participation, as well as strategies for minority recruitment, modifications of study design, and cost issues. Formal evaluation of recruitment strategies has been limited. Most investigators present descriptive reports of their experience in recruiting diverse populations into clinical trials. Research into the issues presented and rigorous testing of specific strategies is needed. A series of steps that are essential to effective clinical trials recruitment of diverse populations is presented.

Clinical Trials as Topic↗
PubMed1995

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.

Adult↗
PubMed1995

Prostate cancer risk in U.S. blacks and whites with a family history of cancer.

Prostate cancer occurs more frequently in U.S. blacks than whites. A population-based case-control study which investigated the association with family history of cancer was carried out among 981 men (479 black, 502 white) with pathologically confirmed prostate cancer, diagnosed between August 1, 1986, and April 30, 1989, and 1,315 controls (594 black, 721 white). Study subjects, aged 40-79, resided in Atlanta, Detroit, and 10 counties in New Jersey, geographic areas covered by population-based cancer registries. Prostate cancer risk was significantly elevated among those who reported a history of prostate cancer in first-degree relatives (O.R. = 3.2; 95% C.I.: 2.0-5.0), with blacks and whites having similarly elevated risks. These risks were unchanged by statistical adjustment for job-related socio-economic status, education, income, and marital status. Overall, the ORs associated with history of prostate cancer in fathers and brothers were 2.5 (95% C.I.: 1.5-4.2) and 5.3 (95% C.I.: 2.3-12.5), respectively. Risks associated with a family history of prostate cancer were consistently elevated among younger and older subjects. Only small non-significant excesses of prostate cancer risk were associated with a family history of breast, colorectal, or other cancers. While familial occurrence is a key risk factor for prostate cancer and likely to be genetically based, the similar familial risks among blacks and whites suggest that the ethnic disparity in incidence is influenced by environmental factors.

Adult↗
PubMed1995

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.

Adenocarcinoma↗
PubMed1995

U.S. farm women's participation in breast cancer screening practices.

BACKGROUND: Surveys of women in the general population indicate that women are being screened for breast cancer at a much lower rate than recommended. There has been a concern that women living in rural areas may be screened for breast cancer even less often than women in urban or suburban areas because of reduced access to health practitioners. METHODS: A random sample of farm women age 40 years or older from 4 rural counties in Michigan was surveyed on knowledge, attitudes, and use of breast cancer screening. RESULTS: Six hundred eighty farm women completed a questionnaire. This was a response rate of 63.8%. The percentages of farm women who reported ever having had a mammogram, having had a mammogram in the past 3 years, and having had a mammogram in the last year were 80.6, 73.7, and 51.9%, respectively. The frequency of clinical breast examinations parallelled mammography usage at slightly higher percentages. Mammogram usage increased with higher education, income, and insurance coverage. Usage decreased in women age 75 years or older (ever 63.1%, in the last 3 years 58.2%, and in the last year 40.4%). Farm women were generally knowledgeable about symptoms and signs of breast cancer and understood the benefit of screening. There was, however, a range of answers on when to start or stop having a mammogram. Among farm women who reported not having a mammogram recently, the most important reasons were: haven't had any problems (29.4%), wasn't recommended by a doctor (14.3%), and procrastinated (11.3%). CONCLUSIONS: Farm women in this survey reported having had breast cancer screening at rates similar to or above those in the general population. Because of a limited response rate (63.5%) and the relative affluence of the farming community in the 4 counties surveyed, these results are probably not generalizable to all populations of farm or rural women.

Adult↗
PubMed1995

Human exposure to polychlorinated biphenyls (PCBs): a critical assessment of the evidence for adverse health effects.

Results from epidemiologic studies involving human exposures to polychlorinated biphenyls (PCBs) are often used to estimate the potential risk or hazard posed by the presence of these chemicals in the workplace or the environment. The use of results and conclusions from individual studies requires an assessment of the scientific quality of the information contained in published reports. The results of a critical review of the scientific literature reported here should be an aid to those who are interested in risk evaluations surrounding exposures to PCBs. There are diverse approaches that one could take to an evaluation of scientific reports of the health hazards of various chemicals. We present one approach to assessing the strengths and weaknesses of studies conducted to understand the potential association between PCB exposure and human health effects. A comprehensive review of the scientific literature involving human exposures to PCBs was performed and each study was evaluated on the basis of a defined set of criteria that were considered standards in epidemiologic research. Two of the 39 occupational studies reviewed provided positive evidence and 3 suggestive evidence for an exposure-related effect, whereas none of the 33 studies where exposure had occurred in the natural environment provided positive or suggestive evidence of an association with adverse effects.

Environmental Exposure↗
PubMed1995

Mammography usage and knowledge about breast cancer in a Michigan farm population before and after an educational intervention.

The purpose of this study was to identify factors associated with the use of mammography screening in a farm population, before and after a community-based educational intervention. The educational intervention included sending individual mailings containing information about breast cancer risk and community sources for screening, and providing information and screening at local county fairs and agricultural community fairs. The authors used multivariate analytic methods to analyze the responses, reported by 1,545 women, to discern the roles of sociodemographic, attitudinal, and knowledge variables in this population's breast cancer screening practices. Results showed that the rural participants in both the intervention and the control communities demonstrated significant changes in knowledge and attitudes about breast cancer. Mammography usage was significantly higher among women who had higher scores on the knowledge and awareness assessments. Education--rather than income, insurance coverage, or family history of breast cancer--emerged in multivariate analyses as the most significant predictor of knowledge and awareness score levels associated with greater use of mammography. Implications of this study include support for education that emphasizes the benefits of early detection of breast cancer for all women.

Adult↗
PubMed1995

Maternal exposure to N-nitrosatable drugs as a risk factor for childhood brain tumours.

BACKGROUND: Animal models suggest that compounds containing a nitrosyl group (N-nitroso compounds (NNO)) can act as potent transplacental carcinogens. Many common drug formulations have the potential to undergo nitrosation in vivo. The association between maternal use of nitrosatable drugs during pregnancy and development of brain tumours in the offspring was examined in a SEER-based case-control study. METHODS: Maternal exposure to nitrosatable drugs during pregnancy was compared among 361 childhood brain tumour cases and 1083 matched controls recruited through random-digit dialing. RESULTS: There was no increase in risk observed for childhood brain tumours overall (OR = 1.15; 95% CI: 0.69-1.94) or for astrocytomas individually (OR = 1.16; 95% CI: 0.50-2.69). A slight elevation in risk was noted for medulloblastomas (OR = 1.47; 95% CI: 0.28-7.62) and 'other' tumours (OR = 1.27; 95% CI: 0.56-2.86), however, both estimates were based on small numbers. CONCLUSIONS: Our findings suggest that no increased risk of childhood brain tumours was associated with maternal exposure to nitrosatable drugs. The study results should be viewed with caution given the imprecision of the point estimates as well as the lack of data on specific timing and dosage of exposure and degree of nitrosatability of drugs taken.

Astrocytoma↗
PubMed1995

Cancer incidence among women in the workplace: a study of the association between occupation and industry and 11 cancer sites.

Few studies of the occupational etiology of cancer have focused upon the risks that women experience in the workplace. In this case-referent study of 11 cancer sites (lung, colon, rectum, bladder, esophagus, liver, salivary gland, stomach, eye, melanoma of the skin, mesothelioma), 7686 women in the Detroit area were interviewed to obtain lifetime histories of employment, tobacco use, and adult health, as well as demographic information. The results provide both methodologic and substantive leads for future investigations of the association between women's employment and their risk of cancer. We found that 63% of respondents had a usual occupation of housewife. Methodologic issues are discussed about the implications of this finding for sample size and statistical analysis when conducting such studies. New observations that merit further investigation include an association between salivary gland cancer and employment in hairdressing shops, esophageal cancer and employment in restaurants, and bladder cancer and employment in computer manufacturing. Further research is needed to understand the occupational etiology of cancer among women; such studies must consider specific methodologic issues.

Case-Control Studies↗
PubMed1995

Stomach cancer risk among black and white men and women: the role of occupation and cigarette smoking.

This population-based case-control study assesses the risk of stomach cancer among black and white men and women. The association of occupational risk factors and cigarette smoking with stomach cancer was analyzed using 739 stomach cancer cases and 3750 population controls. Complete occupational and tobacco-use histories were obtained by telephone interview. Significant increases in stomach cancer were observed among black men (odds ratio [OR] = 2.0), white women (OR = 1.7), and black women (OR = 1.4) who had ever smoked. The majority of occupations with significant increases in risk were among white men and included agricultural workers (OR = 2.6), driver sales (OR = 3.8), assemblers (OR = 2.0), mechanics (OR = 2.2), and material movers (OR = 2.9). Black women employed as assemblers (OR = 5.4) and white women employed as food workers (OR = 4.0) also had significant ORs. Evaluating occupations with possible dust exposure, we found no association between dust exposure and stomach cancer.

Adult↗
PubMed1994

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.

Adult↗
PubMed1994

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.

Adult↗