Search PubMed⌕ Search

Biomedical subjects

C A Swanson

Publications and source records attributed to C A Swanson.

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

Body weight: estimation of risk for breast and endometrial cancers.

Consistent, positive, and independent associations between body weight or body mass index (BMI), weight gain, and various measures of central adiposity and the incidence of endometrial cancer exist. Increases in relative risks of 2-3.5 are reported for women with BMIs (in kg/m2) > or = 28-30, for women in the fourth compared with the first quartile of measures of central adiposity, and for women with weight gains from young adulthood to middle age of > or = 27 kg. Furthermore, endometrial cancer mortality is increased in heavier and taller women. Associations between breast cancer incidence and these measures of adiposity vary by age and menopausal status at the time of diagnosis. Heavier women appear to be at decreased risk for developing premenopausal breast cancer; relative risks of approximately 0.6 were reported for women with BMIs > or = 26-27. Conversely, heavier women are at increased risk of developing and dying from postmenopausal breast cancer. Although contradictory findings have been observed in cohort studies, modest increases in relative risks on the order of 1.2-1.5 were reported in older postmenopausal women with BMIs of > or = 28-30. Furthermore, adult weight gain and increased central adiposity have been consistently and independently associated with an increased risk for postmenopausal breast cancer. No significant associations have been observed between weight loss and postmenopausal breast cancer incidence. These findings indicate that avoidance of weight gain and accumulation of central body fat during adult life may reduce risk of both endometrial and postmenopausal breast cancer.

Adult↗
PubMed1996

Use of selenium concentration in whole blood, serum, toenails, or urine as a surrogate measure of selenium intake.

We examined the validity of using the selenium level in a single biological specimen as a surrogate measure of usual intake. We used data from 77 free-living adults from South Dakota and Wyoming. Subjects provided multiple 1-day duplicate-plate food composites, repeated specimens of blood and toenails, and 24-hour urine collections. We developed a statistical calibration method that incorporated measurement error correction to analyze the data. The Pearson correlation coefficients between selenium intake and a single selenium status measure, after deattenuation to adjust for the effect of within-person variation in intake, were: 0.78 for whole blood, 0.74 for serum, 0.67 for toenails, and 0.86 for urine. We present formulas to estimate the intake of individuals, based on selenium levels in a single specimen of blood, toenails, or urine. In these data, the concentration of selenium in a single specimen of whole blood, serum, or toenails served reasonably well as a measure for ranking subjects according to long-term selenium intake but provided only a rough estimate of intake for each subject.

Adult↗
PubMed1996

Breast enlargement and reduction: results from a breast cancer case-control study.

In a population-based case-control study of breast cancer that included 2174 cases and 2009 population controls under 55 years of age, prior breast implants were reported by 36 cases versus 44 controls. After adjustment for the matching factors as well as variables associated with both breast cancer risk and breast enlargement (race, family history of breast cancer, body size, screening history), the relative risk of breast cancer associated with a prior implant was 0.6 (95% CI 0.4-1.0). The reduced risk persisted with increasing interval since surgery, arguing against selection bias as an explanation. Further, although a deficit of in situ tumors was seen among women with implants (RR = 0.2), the risk associated with implants remained reduced for both localized and distant tumors (RR = 0.8 for both stages). In a smaller group of women who had prior breast reduction surgery (10 cases, 13 controls), a reduced risk of breast cancer also was observed (RR = 0.7, 95% CI 0.3-1.6). The results of this study must be interpreted cautiously because of the small number of women involved and reliance on patient reports of prior operations. In not showing any elevation in breast cancer risk following a breast implant, our results confirm several record linkage studies but contradict some clinical studies that suggest an adverse effect. Additional investigations are needed in relation to specific types of breast implants, including the polyurethane-coated implants, which have been linked to high cancer rates in laboratory animals.

Adult↗
PubMed1996

Recall of body weight and body size estimation in women enrolled in the breast cancer detection and demonstration project (BCDDP).

OBJECTIVE: To examine the relationship between body mass index (BMI) and pictorial representations of body size in women from young adulthood to late mid-life. DESIGN: Retrospective, descriptive study of BMI and pictorial estimation of body size. SUBJECTS: 5,807 women age 33-77 years enrolled in the National Cancer Institute's and American Cancer Society Breast Cancer Detection and Demonstration Project (BCDDP). MEASUREMENTS: Body weight and height were measured in 1973. In 1977, a subset of the cohort recalled their usual height and weight at 10 y intervals starting at age 20. In 1987, subjects reported their usual and current weight and selected one of nine pictorials best representing their body size at ages 15, 25, 40, 50 and +60 y. RESULTS: For the cohort, and among White women, Pearson correlations between recalled BMI (Kg/M2) and pictorials for each decade ranged from 0.62-0.67 and was 0.80 for current BMI and current pictorial. The range of correlations between pictorials and recalled BMI for other race/ethnic groups were 0.72-0.87 (Black), 0.53-0.75 (Hispanic) and 0.28-0.87 (Asian). Among a subset of women with data on measured BMI, recalled BMI and pictorials at specific ages, the correlation between pictorials and measured BMI was 0.75, compared to the correlation between recalled BMI and measured BMI which was 0.89. CONCLUSION: Correlations are higher between recalled BMI and measured BMI compared to the correlation between pictorials and measured BMI. Therefore, estimates of body size by pictorials alone may not be appropriate for epidemiological investigations. Alternate uses of pictorials may include assessment body weight in low literate populations or in instances where body weight is not or has not been measured.

Adult↗
PubMed1995

High concentrations of the carcinogen 2-amino-1-methyl-6-phenylimidazo- [4,5-b]pyridine (PhIP) occur in chicken but are dependent on the cooking method.

Heterocyclic aromatic amines (HAAs) are mutagenic and carcinogenic compounds found in meats cooked at high temperatures. Although chicken is consumed in large quantities in the United States, there is little information on its HAA content. The objective of this study was to measure the five predominant HAAs (IQ, MeIQ, MeIQx, DiMeIQx, and PhIP) in chicken cooked by various methods to different degrees of doneness. Chicken breasts were panfried, oven-broiled, or grilled/barbecued. Whole chickens were roasted or stewed. Skinless, boneless chicken breasts were cooked to three degrees of doneness: just until done, well done, or very well done. High levels of PhIP (ranging from 12 to 480 ng/g cooked meat) were found in chicken breasts when panfried, oven-broiled, and grilled/barbecued but not in while roasted or stewed chicken. PhIP concentration increased in skinless, boneless chicken breast with longer cooking time, higher internal temperature, and greater degree of surface browning. PhIP concentration was also high in chicken breasts cooked with skin and bones. MeIQx and DiMeIQx levels increased with the degree of doneness, whereas IQ and MeIQ were not detectable in any of these chicken samples. Certain cooking methods produce PhIP, a known colon and breast carcinogen in rodents and possibly a human carcinogen, at substantially higher levels in chicken than has been reported previously in red meat.

Animals↗
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

Atomic and residue hydrophilicity in the context of folded protein structures.

Water-protein interactions drive protein folding, stabilize the folded structure, and influence molecular recognition and catalysis. We analyzed the closest protein contacts of 10,837 water molecules in crystallographic structures to define a specific hydrophilicity scale reflecting specific rather than bulk solvent interactions. The tendencies of different atom and residue types to be the nearest protein neighbors of bound water molecules correlated with other hydrophobicity scales, verified the relevance of crystallographically determined water positions, and provided a direct experimental measure of water affinity in the context of the folded protein. This specific hydrophilicity was highly correlated with hydrogen-bonding capacity, and correlated better with experimental than computationally derived measures of partitioning between aqueous and organic phases. Atoms with related chemistry clustered with respect to the number of bound water molecules. Neutral and negatively charged oxygen atoms were the most hydrophilic, followed by positively-charged then neutral nitrogen atoms, followed by carbon and sulfur atoms. Agreement between observed side-chain specific hydrophilicity values and values derived from the atomic hydrophilicity scale showed that hydrophilicity values can be synthesized for different functional groups, such as unusual side or main chains, discontinuous epitopes, and drug molecules. Two methods of atomic hydrophilicity analysis provided a measure of complementarity in the interfaces of trypsin:pancreatic trypsin inhibitor and HIV protease:U-75875 inhibitor complexes.

Amino Acids↗
PubMed1995

Breastfeeding and breast cancer risk.

A population-based case-control study of breast cancer with a focus on premenopausal women under 45 years of age, conducted in three geographic regions of the United States, enabled the evaluation of risk in relation to varying breastfeeding practices. Among premenopausal parous women (1,211 cases, 1,120 random-digit-dialing controls), a history of breastfeeding for two or more weeks was associated with a relative risk (RR) of 0.87 (95 percent confidence interval [CI] = 0.7-1.0). This relationship was not altered substantially by removing from the reference group women who had problems with breastfeeding in the first two weeks, including those with insufficient milk production. Risk was not related substantially to number of children breastfed or length of breastfeeding, although a relatively low risk was observed among those breastfeeding for the longest duration examined (RR = 0.67, CI = 0.4-1.1 for an average period per child of 72 or more weeks). Women who began to breastfeed at a young age (< 22 years) experienced the greatest reduction in risk, but other timing parameters (e.g., interval since first or last breastfeeding) were not predictive of risk. Risks were not modified substantially by age or menopause status, although the number of menopausal subjects examined was limited. Use of medications to stop breast milk was unrelated to risk (RR = 1.04). The results of this study do not support the notion that breastfeeding substantially reduces breast cancer risk; however, this may reflect the fact that most of our study subjects breastfed only for limited periods of time (average breastfeeding per child of 30 weeks). Further studies are needed to clarify the relationship of breastfeeding to breast cancer risk, and to determine possible etiologic mechanisms underlying any observed associations.

Adult↗
PubMed1994

The relations between cervical cancer and serological markers of nutritional status.

We evaluated whether differences in serological nutrient indicators between cases and controls were likely to be due to different usual levels for cases or to altered metabolism due to disease. Blood samples obtained as part of a case-control study of invasive cervical cancer conducted in Latin America were evaluated for case-control differences and for trends with stage of disease. Serum alpha- and beta-carotene, cryptoxanthin, and alpha- and gamma-tocopherol showed no trend with extent of disease, although Stage IV cases had lower alpha- and beta-carotene values than did other cases. A slight trend of decreasing values with stage was observed for serum retinol, lycopene, and lutein. For cholesterol and triglyceride concentrations, an inverse trend was observed with stage of disease, which suggested a clinical effect of the disease on blood lipids. Adjustment for smoking, alcohol intake, or oral contraceptive use did not alter observed relations, nor was there evidence that the altered blood nutrient levels differed by histological type. These data suggest that serum values for some carotenoids from Stage I, II, and III cervical cancer are suitable for etiological studies, but spurious results may be obtained if late-stage cases are included. Evidence of trends with severity of disease for cholesterol and triglycerides, and possibly for retinol, lycopene, and lutein, suggest that special attention be given to disease effects of these nutrients in studies of cervical cancer.

Adult↗
PubMed1993

Dietary associations in a case-control study of endometrial cancer.

Despite the established role of obesity in the etiology of endometrial cancer, limited data are available from analytical epidemiologic studies on the association of risk with dietary factors. A case-control study of 399 cases and 296 controls conducted in five areas of the United States from 1 June 1987 to 15 May 1990, enabled evaluation of risk related to dietary intakes adjusted for potential confounders. Caloric intake was associated modestly with increased risk (odds ratio [OR] = 1.5, 95 percent confidence interval [CI] = 0.9-2.5 for highest cf lowest quartiles of intake), with the principal contributors being fat and protein calories. After adjustment for other risk factors, including body mass, increased risk was associated with higher intakes of fat. Several components of fat investigated were associated with increased risk, although associations were slightly stronger for saturated fat (OR = 2.1, CI = 1.2-3.7) and oleic acid (OR = 2.2, CI = 1.2-4.0) than for linoleic acid (OR = 1.6, CI = 0.9-2.8). Food-group analyses showed intake of complex carbohydrates--and specifically of breads and cereals--associated with reduced risks (OR = 0.6, CI = 0.4-1.1), whereas animal fat and fried foods were associated with elevated risks (OR = 1.5 and 1.7, respectively). The relations of endometrial cancer with animal fat and complex carbohydrates were independent. No consistent associations were noted for intakes of cholesterol, fiber, vitamins A and C, individual carotenoids, or folate-rich foods. These data imply an etiologic role for a diet rich in total fat and/or animal fat and low in complex carbohydrates with endometrial cancer.(ABSTRACT TRUNCATED AT 250 WORDS)

Body Mass Index↗
PubMed1993

Decreased melphalan accumulation in a human breast cancer cell line selected for resistance to melphalan.

An in vitro model of acquired melphalan resistance was developed by serial incubation of an MCF-7 human breast cancer cell line in increasing concentrations of melphalan. The resulting derivative cell line, Me1R MCF-7, was 30-fold resistant to melphalan. Uptake studies demonstrated decreased initial melphalan accumulation in Me1R MCF-7 cells. Inverse-reciprocal plots of initial melphalan uptake revealed a 4-fold decrease in the apparent Vmax of Me1R MCF-7 compared with WT MCF-7 (516 amol cell-1 min-1 vs 2110 amol cell-1 min-1 respectively) as well as a decrease in the apparent Kt (36 microM vs 70 microM respectively). Two amino acid transporters have previously been identified as melphalan transporters: system L, which is sodium-independent and inhibited by 2-amino-bicyclo[2,2,1]heptane-2-carboxylic acid (BCH), and system ASC which is sodium dependent and unaffected by BCH. At low concentrations of melphalan (3-30 microM), 1mM BCH competition eliminated the differences between the two cell lines, thus implicating an alteration of the system L transporter in the transport defect in the resistant cells. Me1R MCF-7 cells were also evaluated for glutathione-mediated detoxification mechanisms associated with melphalan resistance. There was no difference between Me1R MCF-7 and WT MCF-7 in glutathione content, glutathione-S-transferase activity and expression of pi class glutathione S-transferase RNA. In addition, buthionine sulfoximine did not reverse melphalan resistance in Me1R MCF-7 cells. Therefore, Me1R MCF-7 cells provide an in vitro model of transport-mediated melphalan resistance in human breast cancer cells.

Amino Acid Transport Systems↗
PubMed1993

A comparison of diets of blacks and whites in three areas of the United States.

Dietary factors may contribute to the increased cancer risk of blacks. As a first step to explore this hypothesis, we examined food frequency data obtained by interview with 1,976 adults (881 blacks and 1,095 whites) randomly selected from three areas of the United States. The a priori hypothesis was that blacks were more likely to consume diets low in fruits and vegetables and/or high in fat, particularly saturated fat. Contrary to expectation, blacks were more frequent consumers of fruits and vegetables considered to be protective against cancer (e.g., citrus fruits, cruciferous vegetables, and vegetables rich in vitamins A and C). Intake of both total and saturated fat was slightly lower among blacks than whites. This analysis does not rule out a role for these dietary factors in the etiology of cancer but indicates that ascribing the excess cancer risk among blacks to their frequency of fruit and vegetable consumption or intake of fat per se is inadequate. This suggests that alternative dietary explanations for the racial disparity in cancer risk should be pursued in future studies.

Adult↗
PubMed1993

Moderate alcohol consumption and the risk of endometrial cancer.

In a multicenter case-control study that included 400 cases and 297 controls, we examined the relation of moderate alcohol consumption to risk of endometrial cancer. We estimated average weekly intake of alcohol during adulthood from the reported frequency of intake of beer, wine, and liquor. The relative risk of endometrial cancer was 0.82 (95% confidence interval = 0.6-1.2) among women who drank, compared with lifelong abstainers. The weak protective effect of alcohol was due to a stronger inverse association among young women (< 55 years). In young women, the age-adjusted relative risks for three levels of drinking ( < 1, 1-4, > 4 drinks per week), from lowest to highest, were 0.78, 0.64, and 0.41 compared with nondrinkers. The risk estimates were not materially altered after adjustment for a variety of factors related to alcohol intake and to low risk of the disease (for example, smoking, oral contraceptive use, low body mass index, increased physical activity). The protective effect of alcohol could not be attributed to one particular type of alcohol-containing beverage, but beer appeared to have the most pronounced effect. These results suggest an inverse association between moderate alcohol consumption and endometrial cancer risk among young women, but support for a causal association is qualified and requires confirmation.

Adult↗
PubMed1992

Relation of obesity and body fat distribution to endometrial cancer in Shanghai, China.

In a case-control study involving 268 cases of endometrial cancer and an equal number of population controls, we assessed the relationship of risk to body weight and fat distribution, examining weight at various ages and current anthropometric measurements. Weight gain during later adulthood and resultant high body masses were important risk predictors, indicating that obesity is an important risk factor, even in an area where the prevalence of obesity and incidence of endometrial cancer are low. Certain fat distribution patterns were related to risk of endometrial cancer independent of general obesity. In particular, fat deposits on the trunk were associated with elevated risks, with the odds ratio for the highest versus lowest quartile of subscapular skinfolds remaining significant even after adjustment for body mass index (odds ratio = 2.9; 95% confidence interval, 1.1-7.3). Central versus peripheral obesity, as measured by the subscapular:triceps ratio, also was related to increased risk, although the association failed to remain significant after adjustment for body mass (highest to lowest quartile, odds ratio = 1.7). In contrast, upper body obesity, as assessed by the waist:thigh ratio, was unrelated to risk. These results support the need for future studies assessing the relationship of hormonal and other biological parameters of fat distribution to assist in identifying causal mechanisms for this tumor.

Adolescent↗
PubMed1992

Dietary determinants of lung-cancer risk: results from a case-control study in Yunnan Province, China.

The relation between diet and lung cancer was studied among male residents of a mining community in Yunnan Province. After obtaining food frequency data from subjects or proxies, we compared diets of 428 cases, aged 35-74 years, and 1,011 age-matched controls. Cases tended to consume slightly more rice, but less protein-rich foods (i.e., bean curd, meat, eggs) and vegetables than did controls. The relative risks of lung cancer across increasing quartiles of meat (i.e., pork) consumption, for example, were 1.00, 0.67, 0.72 and 0.46 (p for trend less than 0.01). The relative risks of lung cancer across increasing quartiles of consumption of dark-green, leafy vegetables were 1.00, 0.62, 0.52 and 0.41 (p for trend less than 0.01). Although specific dietary constituent(s) responsible for the protective effect of vegetable consumption could not be identified, carotenoids other than beta-carotene, or compounds in cruciferous or Allium vegetables, are possibilities.

Animals↗
PubMed1992

Height and weight at various ages and risk of breast cancer.

A study of 1529 breast cancer patients and 1901 control subjects enabled evaluation of risk in relation to lifetime changes in body size. Tallness, regardless of when achieved, was associated with an increased risk of breast cancer diagnosed at both young (< 50 years) and older ages, with adult height of 68 in or more increasing risk by nearly 50 to 80% compared with statures of less than 62 in. The association of risk with weight was less clear. Subjects who described themselves as heavier than average at ages 8 to 9 or 16 years were at reduced risk, particularly for older-onset breast cancer. Higher body mass indices based on reported weights during early adulthood were also associated with reduced risk. Measures of body mass beyond the age of 20, however, were less strongly related to risk. These inconsistent patterns appeared to be explained by an effect on risk of weight gain later in life, which was related to reduced risks for young-onset breast cancer and increased risks for later disease. The effect of weight change for early-onset breast cancer was not restricted to in situ cancers and could therefore not be attributed to detection bias. The direct relationship of body mass change with older onset disease was restricted to invasive cancers, consistent with observations of poor breast cancer prognosis among obese women. Further attention on the relationship of anthropometric variables to risk of breast cancer should focus on the timing of weight gain as well as the distribution of body fat.

Adolescent↗
PubMed1991

Human [74Se]selenomethionine metabolism: a kinetic model.

A study was undertaken to investigate the pharmacokinetics of an organically bound form of selenium. Six adults received a single oral 200-micrograms dose of 74Se as L-selenomethionine. A kinetic model was developed to simultaneously account for the appearance and disappearance of the tracer in plasma, urine, and feces. The model included absorption distributed along the gastrointestinal tract, uptake by the liver-pancreas subsystem, enterohepatic recirculation, distribution to two large tissue pools, and transport through four components of the plasma pool. Average turnover time of the plasma components varied from 0.01 to 1.1 d. The turnover time in the liver-pancreas subsystem ranged from 1.6 to 3.1 d. Turnover time ranged from 61 to 86 d in the peripheral tissues with the slowest turnover. The whole-body residence time was approximately five-fold greater than the turnover time of the tissue pool with the slowest turnover, reflecting substantial reutilization of labeled material.

Absorption↗