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C F Lynch

Publications and source records attributed to C F Lynch.

At least 37 records · Page 2Linked to original sources
PubMed2001

Occupational risk factors for brain cancer: a population-based case-control study in Iowa.

A number of occupations and industries have been inconsistently associated with the risk of brain cancer. To further explore possible relationships, we conducted a population-based case-control study of brain glioma in the state of Iowa, involving 375 histologically confirmed incident cases and 2434 population-based controls. Among men, the industries and/or occupations that had a significantly increased risk for employment of more than 10 years included roofing, siding, and sheet metalworking; newspaper work; rubber and plastics products, particularly tires and inner tubes; miscellaneous manufacturing industries; wholesale trade of durable goods, grain, and field beans; cleaning and building service occupations; miscellaneous mechanics and repairers; and janitors and cleaners. Subjects who worked in plumbing, heating, and air conditioning; electrical services; gasoline service stations; and military occupations also experienced a significantly increased risk. Among women, significant excess risk was observed for occupations in agricultural services and farming, apparel and textile products, electrical and electronic equipment manufacturing, various retail sales, record-keeping, and restaurant service. Workers in industries with a potential for gasoline or motor exhaust exposures experienced a non-significant excess risk of brain glioma.

Adult↗
PubMed2000

Treatment-associated leukemia following testicular cancer.

BACKGROUND: Men with testicular cancer are at an increased risk of leukemia, but the relationship to prior treatments is not well characterized. The purpose of our study was to describe the risk of leukemia following radiotherapy and chemotherapy for testicular cancer. METHODS: Within a population-based cohort of 18 567 patients diagnosed with testicular cancer (from 1970 through 1993), a case-control study of leukemia was undertaken. Radiation dose to active bone marrow and type and cumulative amount of cytotoxic drugs were compared between 36 men who developed leukemia and 106 matched control patients without leukemia. Conditional logistic regression was used to estimate the relative risk of leukemia associated with specific treatments. All P values are two-sided. RESULTS: Radiotherapy (mean dose to active bone marrow, 12.6 Gy) without chemotherapy was associated with a threefold elevated risk of leukemia. Risk increased with increasing dose of radiation to active bone marrow (P for trend =.02), with patients receiving radiotherapy to the chest as well as to the abdominal/pelvic fields accounting for much of the risk at higher doses. Radiation dose to active bone marrow and the cumulative dose of cisplatin (P for trend =.001) were both predictive of excess leukemia risk in a model adjusted for all treatment variables. The estimated relative risk of leukemia at a cumulative dose of 650 mg cisplatin, which is commonly administered in current testicular cancer treatment regimens, was 3.2 (95% confidence interval = 1.5-8.4); larger doses (1000 mg) were linked with statistically significant sixfold increased risks. CONCLUSIONS: Past treatments for testicular cancer are associated with an increased risk of leukemia, with evidence for dose-response relationships for both radiotherapy and cisplatin-based chemotherapy. Statistically nonsignificant excesses are estimated for current radiotherapy regimens limited to the abdomen and pelvis: Among 10 000 patients given a treatment dose of 25 Gy and followed for 15 years, an excess of nine leukemias is predicted; cisplatin-based chemotherapy (dose, 650 mg) might result in 16 cases of leukemia. The survival advantage provided by current radiotherapy and chemotherapy regimens for testicular cancer far exceeds the small absolute risk of leukemia.

Adult↗
PubMed2000

Residential radon gas exposure and lung cancer: the Iowa Radon Lung Cancer Study.

Exposure to high concentrations of radon progeny (radon) produces lung cancer in both underground miners and experimentally exposed laboratory animals. To determine the risk posed by residential radon exposure, the authors performed a population-based, case-control epidemiologic study in Iowa from 1993 to 1997. Subjects were female Iowa residents who had occupied their current home for at least 20 years. A total of 413 lung cancer cases and 614 age-frequency-matched controls were included in the final analysis. Excess odds were calculated per 11 working-level months for exposures that occurred 5-19 years (WLM(5-19)) prior to diagnosis for cases or prior to time of interview for controls. Eleven WLM(5-19) is approximately equal to an average residential radon exposure of 4 pCl/liter (148 Bq/m3) during this period. After adjustment for age, smoking, and education, the authors found excess odds of 0.50 (95% confidence interval: 0.004, 1.81) and 0.83 (95% percent confidence interval: 0.11, 3.34) using categorical radon exposure estimates for all cases and for live cases, respectively. Slightly lower excess odds of 0.24 (95 percent confidence interval: -0.05, 0.92) and 0.49 (95 percent confidence interval: 0.03, 1.84) per 11 WLM(5-19) were noted for continuous radon exposure estimates for all subjects and live subjects only. The observed risk estimates suggest that cumulative ambient radon exposure presents an important environmental health hazard.

Adult↗
PubMed2000

Tea consumption and risk of bladder and kidney cancers in a population-based case-control study.

Recent epidemiologic studies have suggested that tea may be protective against cancers of the urinary tract. The authors examined the association between usual adult tea consumption and risk of bladder and kidney cancers in a population-based case-control study that included 1,452 bladder cancer cases, 406 kidney cancer cases, and 2,434 controls. For bladder cancer, the age- and sex-adjusted odds ratios (OR) (95% confidence intervals (CI)) referent to nonusers of tea were 0.9 (0.7, 1.1) for <1.0 cup/day, 1.0 (0.8, 1.2) for 1.0-2.6 cups/day, and 0.9 (0.7, 1.1) for >2.6 cups/day (cutpoints for users based on the tertile distribution among controls). When more extreme cutpoints were used, persons who consumed >5 cups/day (>90th percentile) had a suggestive decreased risk (OR = 0.7; 95% CI 0.5, 1.0), but there was no evidence of a dose-response relation. In analyses stratified by median total beverage intake (2.6 liters/day), there was an inverse association with tea use among persons who consumed less than the median (OR = 0.5; 95% CI 0.3, 0.8) but no association for persons who consumed at or above the median. In contrast, for kidney cancer, there was no association with tea use. Adjustment for site-specific risk factors did not alter these results. This study offers only minimal support for an inverse association between tea consumption and bladder or kidney cancer risk.

Adult↗
PubMed2000

Lifestyle and anthropometric risk factors for prostate cancer in a cohort of Iowa men.

PURPOSE: Several lines of evidence suggest that prostate cancer has a hormonal etiology. We evaluated factors known to modulate the endocrine system, including alcohol and tobacco use, physical activity, and obesity as risk factors for prostate cancer. METHODS: Cancer-free controls who participated in a population-based case-control study from 1986-1989 (81% response rate) were followed through 1995 for cancer incidence by linkage to the Iowa Cancer Registry; 101 incident prostate cancers were identified. RESULTS: Compared with non-users of alcohol, men who consumed <22 grams alcohol per week (relative risk [RR] = 1.1; 95% Confidence Interval [CI] 0.6-2.1), 22-96 grams alcohol per week (RR = 2.6; 95% CI 1.4-4. 6) and >96 grams alcohol per week (RR = 3.1; 95% CI 1.5-6.3) were at increased risk of prostate cancer after adjustment for age, family history of prostate cancer, body mass index, total energy, and intake of carbohydrate, linoleic acid, lycopene, retinol, and red meat (p for trend < 0.0001). The respective RRs were similar when assessing type of alcohol consumed (beer, wine or liquor) or when well-differentiated, localized tumors were excluded. Body mass index was only weakly and positively associated with prostate cancer after adjustment for age, but this association strengthened after multivariate adjustment and exclusion of well-differentiated, localized tumors. For the latter tumors, men with a BMI of 24.1-26.6 kg/m(2) and >26.6 kg/m(2) were at elevated risk compared to men with a BMI <24.1 kg/m(2). Tobacco use (cigarettes, cigar/pipe, chewing tobacco and snuff use), height, weight, and both leisure and occupational physical activity were not associated with risk of prostate cancer in this cohort. CONCLUSIONS: These data suggest that in white men obesity is a risk factor for more clinically significant prostate cancer and confirm limited previous reports showing that alcohol consumption is positively associated with prostate cancer and that this risk is not limited to any specific type of alcohol.

Adult↗
PubMed2000

Comparison of heterocyclic amine levels in home-cooked meats with exposure indicators (United States).

OBJECTIVE: To compare indicators of heterocyclic amine (HCA) exposure with HCA concentrations in home-cooked meat samples. METHODS: Pan-fried hamburger and steak samples were obtained from individuals stating a preference for medium, well done and very well done meat. Concentrations of DiMelQx, IFP, MeIQx and PhIP were determined by HPLC. RESULTS: HCA concentrations at the three doneness levels were not significantly different using the participants' self-reported doneness preference to categorize samples. Using doneness levels determined at the time the meat was cooked and photograph analysis to categorize samples, HCA concentrations increased with doneness level and significant differences were observed between the very well done and lower doneness levels. When assigned to doneness levels by photograph analysis, mean concentrations (ng/g cooked meat) of DiMelQx, IFP, MelQx, and PhIP were 0.18, 0.16, 0.65 and 0.47 in well done hamburger and 0.61, 0.74, 1.88 and 2.04 in very well done hamburger. In steak, mean concentrations were 0.24, 0.10, 0.79 and 0.59 in well done steak and 0.45, 0.14, 1.87 and 0.62 in very well done steak. CONCLUSIONS: HCA levels in home-cooked meat samples were significantly different when samples were visually classified for doneness, but not when self-reported doneness preference was used to classify doneness.

Amines↗
PubMed2000

Occupational exposure to formaldehyde and wood dust and nasopharyngeal carcinoma.

OBJECTIVES: To investigate whether occupational exposures to formaldehyde and wood dust increase the risk of nasopharyngeal cancer (NPC). METHODS: A multicentered, population based case-control study was carried out at five cancer registries in the United States participating in the National Cancer Institute's SEER program. Cases (n=196) with a newly diagnosed NPC between 1987 and 1993, and controls (n=244) selected over the same period from the general population through random digit dialing participated in structured telephone interviews which inquired about suspected risk factors for the disease, including a lifetime history of occupational and chemical exposure. Histological type of cancer was abstracted from clinical records of the registries. Potential exposure to formaldehyde and wood dust was assessed on a job by job basis by experienced industrial hygienists who were blinded as to case or control status. RESULTS: For formaldehyde, after adjusting for cigarette use, race, and other risk factors, a trend of increasing risk of squamous and unspecified epithelial carcinomas was found for increasing duration (p=0.014) and cumulative exposure (p=0.033) but not for maximum exposure concentration. The odds ratio (OR) for people cumulatively exposed to >1.10 ppm-years was 3.0 (95% confidence interval (95% CI) 1.3 to 6.6) compared with those considered unexposed. In analyses limited to jobs considered definitely exposed, these trends became stronger. The associations were most evident among cigarette smokers. By contrast, there was no association between potential exposure to formaldehyde and undifferentiated and non-keratinising carcinomas. There was little evidence that exposure to wood dust increased risk of NPC, as modest crude associations essentially disappeared after control for potential exposure to formaldehyde. CONCLUSIONS: These results support the hypothesis that occupational exposure to formaldehyde, but not wood dust, increases risk of NPC. This association seems to be specific to squamous cell carcinomas. Established cohorts of workers exposed to formaldehyde and wood dust should continue to be monitored for NPC and other respiratory cancers. Future studies of NPC should take into account histological type in assessing risk from environmental and host factors.

Adolescent↗
PubMed2000

Second cancers among long-term survivors of Hodgkin's disease diagnosed in childhood and adolescence.

PURPOSE: To quantify the risk of second cancers among long-term survivors of Hodgkin's disease (HD) diagnosed before 21 years of age and to explore sex-, age-, and site-related differences. PATIENTS AND METHODS: We analyzed data from 5,925 pediatric HD patients, including 2,646 10-year and 755 20-year survivors, who were reported to 16 population-based cancer registries in North America and Europe between 1935 and 1994. RESULTS: A total of 157 solid tumors (observed/expected ratio [O/E] = 7.0; 95% confidence interval [CI], 5.9 to 8.2.) and 26 acute leukemias (O/E = 27.4; 95% CI, 17.9 to 40. 2) were reported. Risk of solid tumors remained significantly increased among 20-year survivors (O/E = 6.6, observed [O] = 40, cumulative risk = 6.5%) and persisted for 25 years (O/E = 4.6, O = 15, cumulative risk = 11.7%). Temporal trends for cancers of thyroid, female breast, bone/connective tissue, stomach, and esophagus were consistent with the late effects of radiotherapy. Greater than 50-fold increased risks were observed for tumors of the thyroid and respiratory tract (one lung and one pleura) among children treated before age 10. At older ages (10 to 16 years), the largest number of second cancers occurred in the digestive tract (O/E = 19.3) and breast (O/E = 22.9). Risk of solid tumors increased with decreasing age at HD on a relative but not absolute scale. CONCLUSION: Children and adolescents treated for HD experience significantly increased risks of second cancers at various sites for 2 to 3 decades. Although our results reflect the late effects of past therapeutic modalities, they underscore the importance of lifelong follow-up of pediatric HD patients given early, more aggressive treatments.

Adolescent↗
PubMed2000

Molecular changes in second primary lung and breast cancers after therapy for Hodgkin's disease.

The risk of lung and breast cancer is significantly increased after therapy for Hodgkin's disease (HD), but there are few data that describe the molecular profiles of these tumors. We investigated the genetic abnormalities in second primary lung (n = 19) and breast cancers (n = 19) that follow therapy for HD ("post-HD cancers") and compared these with changes observed in corresponding tumor types (57 lung and 20 breast cancers) arising in the general population ("sporadic cancers"). DNA obtained from archival tissues was examined using PCR-based analyses for loss of heterozygosity and microsatellite alterations (MAs) at several chromosomal regions, TP53 and K-ras gene mutations, and frameshift mutations at minisatellite sequences at the coding regions of several genes (TGF-betaRII, IGFIIR, BAX, hMSH6, and hMSH3). The occurrence of loss of heterozygosity at all chromosomal regions taken together and frequencies at most individual areas were similar for the post-HD and sporadic cancers for both lung and breast sites. The overall frequency of MAs in the post-HD tumors was substantially greater (lung, 2.4-fold, P = 0.004; breast, 4.2-fold, P = 0.16) than that in the respective sporadic cancers. No differences in the pattern of TP53 and K-ras mutations were detected between post-HD and sporadic cancers. No mutations were detected at the minisatellite sequences examined. MAs, which reflect widespread genomic instability, occur at greatly increased frequency in post-HD lung and breast cancers. Although the mechanisms underlying the development of increased MAs are unknown, they have been associated with immunosuppression and radiation exposure. Future research should address the role that MAs, as well as other influences, may play in the development of neoplasias that occur after therapy for HD.

Adenocarcinoma↗
PubMed2000

Knowledge of the Tuskegee study and its impact on the willingness to participate in medical research studies.

The under-representation of racial/ethnic minorities among medical research participants has recently resulted in mandates for their inclusion by the National Institutes of Health (NIH). Therefore, there is a need to determine how history, attitudes, cultural beliefs, social issues, and investigator behavior affect minority enrollment in medical research studies. From January 1998 to March 1999, 179 African-American and white residents of the Detroit Primary Metropolitan Statistical Area (PMSA) participated in a mail and telephone survey designed to examine impediments to African-American participation in medical research studies. Chi-square tests were performed to assess differences between the study groups using the Survey Data Analysis Program (SUDAAN). Eighty-one percent of African Americans and 28% of whites had knowledge of the Tuskegee Study (p = <0.001). Knowledge of the Tuskegee Study resulted in less trust of researchers for 51% of African-Americans and 17% of whites (p = 0.02). Forty-six percent of African-Americans and 34% of whites indicated that their knowledge of the study would affect future research participation decisions (p = 0.25). Of these, 49% of African-Americans and 17% of whites would not be willing to participate in future medical research studies (p = 0.05). This study confirms the need for medical researchers to confront the issue of the Tuskegee Study and its continuing impact on African-Americans' trust of medical research studies.

Adolescent↗
PubMed1999

Drinking water source and chlorination byproducts in Iowa. III. Risk of brain cancer.

The authors conducted a population-based case-control study in Iowa of 375 brain cancer patients and 2,434 controls. A postal questionnaire was used to gather information on lifetime residential history, sources of drinking water, beverage intake, and other potential risk factors. Exposure to chlorination byproducts in drinking water was estimated by combining questionnaire data with historical information from water utilities and trihalomethane levels in recent samples. The analysis included 291 cases (77.6%) and 1,983 controls (81.5%), for whom water quality information was available for at least 70% of lifetime years. Proxies represented 74.4% of cases. The mean number and mean duration of places of residence were comparable between direct and proxy respondents, suggesting little contribution to bias. After multivariate adjustment, odds ratios for brain cancer were 1.0, 1.1, 1.6, and 1.3 for exposure to chlorinated surface water of 0, 1-19, 20-39, and > or =40 years (p trend = 0.1). Among men, odds ratios were 1.0, 1.3, 1.7, and 2.5 (p trend = 0.04), and among women, 1.0, 1.0, 1.6, and 0.7 (p trend = 0.7)). Similar findings were found with estimates of average lifetime level of trihalomethanes. The association was stronger among men with above-median tap water consumption. These observations deserve further attention, especially in view of increasing glioma rates.

Adult↗
PubMed1999

Risk of leukemia after platinum-based chemotherapy for ovarian cancer.

BACKGROUND: Platinum-based chemotherapy is the cornerstone of modern treatment for ovarian, testicular, and other cancers, but few investigations have quantified the late sequelae of such treatment. METHODS: We conducted a case-control study of secondary leukemia in a population-based cohort of 28,971 women in North America and Europe who had received a diagnosis of invasive ovarian cancer between 1980 and 1993. Leukemia developed after the administration of platinum-based therapy in 96 women. These women were matched to 272 control patients. The type, cumulative dose, and duration of chemotherapy and the dose of radiation delivered to active bone marrow were compared in the two groups. RESULTS: Among the women who received platinum-based combination chemotherapy for ovarian cancer, the relative risk of leukemia was 4.0 (95 percent confidence interval, 1.4 to 11.4). The relative risks for treatment with carboplatin and for treatment with cisplatin were 6.5 (95 percent confidence interval, 1.2 to 36.6) and 3.3 (95 percent confidence interval, 1.1 to 9.4), respectively. We found evidence of a dose-response relation, with relative risks reaching 7.6 at doses of 1000 mg or more of platinum (P for trend <0.001). Radiotherapy without chemotherapy (median dose, 18.4 Gy) did not increase the risk of leukemia. CONCLUSIONS: Platinum-based treatment of ovarian cancer increases the risk of secondary leukemia. Nevertheless, the substantial benefit that platinum-based treatment offers patients with advanced disease outweighs the relatively small excess risk of leukemia.

Aged↗
PubMed1999

Characteristics of pesticide use in a pesticide applicator cohort: the Agricultural Health Study.

Data on recent and historic pesticide use, pesticide application methods, and farm characteristics were collected from 35,879 restricted-use pesticide applicators in the first 2 years of the Agricultural Health Study, a prospective study of a large cohort of private and commercial licensed pesticide applicators that is being conducted in Iowa and North Carolina. (In Iowa, applicators are actually "certified," while in North Carolina they are "licensed"; for ease of reference the term license will be used for both states in this paper.) Commercial applicators (studied in Iowa only) apply pesticides more days per year than private applicators in either state. When the types of pesticides being used by different groups are compared using the Spearman coefficient of determination (r2), we find that Iowa private and Iowa commercial applicators tend to use the same type of pesticides (r2=0.88). White and nonwhite private applicators tended to use the same type of pesticides (North Carolina r2=0.89), as did male and female private applicators (Iowa r2=0.85 and North Carolina r2=0.84). There was less similarity (r2=0. 50) between the types of pesticides being used by Iowa and North Carolina private applicators. A greater portion of Iowa private applicators use personal protective equipment than do North Carolina private applicators, and pesticide application methods varied by state. This heterogeneity in potential exposures to pesticides between states should be useful for subsequent epidemiologic analyses using internal comparison groups.

Agriculture↗
PubMed1999

A cohort study of farming and risk of prostate cancer in Iowa.

Although farming has been linked to prostate cancer mortality, few investigations have addressed its association with prostate cancer incidence. We followed a population-based cohort of 1,177 cancer-free men for up to 9 years and identified 81 incident prostate cancers. Men whose usual occupation was farmer were at an increased risk of prostate cancer after adjustment for age, smoking, alcohol, and dietary factors (RR = 1.7; 95% CI = 1.0-2.7). Exclusion of well-differentiated, localized tumors slightly strengthened the association (RR = 2.0; 95% CI = 1.1-3.6). Risk was confined to older (age 70+ years) farmers (RR = 2.2; 95% CI = 1.1-4.3); we found no evidence of an effect among younger farmers (RR = 1.0; 95% CI = 0.4-2.1).

Adult↗
PubMed1999

Cohen's paradox.

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Air Pollutants, Radioactive↗
PubMed1999

Use of Medicare hospital and physician data to assess breast cancer incidence.

OBJECTIVES: Health claims data have the potential of being an inexpensive, timely, and nationally representative source of information about cancer. This study examined the utility of Medicare hospital and physician data as an independent source to identify incident breast cancer cases. METHODS: Data came from Medicare and the National Cancer Institute's SEER cancer registries. From 1992, for women residing in the SEER states (n = 659,260), Medicare hospital and physician claims were reviewed to identify women with a breast cancer diagnosis on a claim (n = 6,784). These women were matched with women in the SEER data who had been diagnosed with breast cancer in 1992 (n = 3,230). The sensitivity, specificity, and positive predictive value (PPV) of the Medicare data were calculated. Logistic regression models were used to identified cancer related procedures reported to Medicare that could distinguish true cases from false positive cases. Predicted values from these models were included to create plots of sensitivity versus false positive rates and sensitivity versus PPV. RESULTS: Medicare hospital data had 62% sensitivity, 99.9% specificity, and 88% PPV. Physician claims increased sensitivity by 14%, with specificity of 99.4%, and a PPV of 10%. Inclusion of additional cancer related diagnoses and procedures improved the ability to distinguish true cases from false positives, although the number of false positive cases remained high. CONCLUSIONS: The Medicare data overall offer limited potential to assess breast cancer incidence, largely because of low sensitivity and poor PPV. The Medicare data may have utility to identify women undergoing selected breast cancer treatments. In addition, the data may be used to help registries focus case-finding efforts, particularly for persons undergoing cancer related treatments.

Breast Neoplasms↗
PubMed1999

Linked insurance-tumor registry database for health services research.

OBJECTIVE: Breast cancer screening and treatment data are often limited to restricted populations, including women older than 65 years old. The goal of this project was to develop procedures to link tumor registry and insurance claims databases on women younger than 65 years old with breast cancer and to assess the accuracy and validity of the linked dataset. METHODS: Iowa Cancer Registry (ICR) and Wellmark Blue Cross/Blue Shield of Iowa (BC/BS) membership files of women with incident in situ or invasive breast cancer from 1989 to 1996 were linked. An automated deterministic match was followed with visual inspection from three independent reviewers applying a matching protocol. Matched and overall registry data were compared to assess population representativeness. Claims from BC/BS for incident cases during 1994 were examined for coding of a recent breast cancer diagnosis or treatment. RESULTS: The final dataset included 4,397 matched cases of patients aged 21 years and older from 1989 to 1996. The sociodemographic and tumor characteristics of the ICR population younger than 65 years old (n = 7,469) with breast cancer or carcinoma in situ were nearly identical with those of the matched patients younger than 65 years old (n = 3,449). Nearly all (96%) of the 445 matched incident cases in 1994 had claims data (CPT, DRG, or ICD-9 code) indicative of breast cancer. Treatment patterns varied by data source, with agreement ranging from 76% to 82%. CONCLUSIONS: The validity and generalizability of these data demonstrate their potential for further health services research among younger insured women with breast cancer. Additionally, the process outlined may be useful for developing other datasets to study other cancers in the population younger than 65 years old.

Adult↗