PubMed Health⌕ Search

Biomedical subjects

Nancy Potischman

Publications and source records attributed to Nancy Potischman.

At least 19 recordsLinked to original sources
PubMed2006

A comparison of two dietary instruments for evaluating the fat-breast cancer relationship.

BACKGROUND: Previous research suggests food diaries may be more efficient than food frequency questionnaires (FFQ) in detecting a dietary fat-breast cancer relationship. We assessed this further using 4 day food records (FRs) and FFQs in a large sample. METHODS: Participants were from the non-intervention group of the dietary modification component of the Women's Health Initiative Clinical Trial: 603 breast cancer cases and 1206 controls matched on age, clinic, and length of follow-up. Relative risks (RRs) were estimated using unconditional logistic regression, adjusted for confounders and for the selection into the trial of women with an FFQ report exceeding 32% calories from fat. Direct comparison of the statistical power of the two instruments used the standardized log RR. An alternative analysis after removing subjects with missing covariate data was also conducted. RESULTS: The RR estimate for breast cancer in the top quintile of total fat intake, adjusted for confounders and total energy, was 1.82 (P for trend 0.02) for the FR but 0.67 for the FFQ (P for trend 0.24). Following adjustment for selection, estimates were 2.09 (P for trend 0.008) for the FR (alternative: 2.54, P for trend 0.006) and 1.71 (P for trend 0.18) for the FFQ (alternative: 1.24, P for trend 0.41). Similar results were seen for fat subtypes, particularly unsaturated fats. Comparisons showed higher statistical power for the FR than the FFQ (e.g. total fat, P = 0.08: alternative P = 0.01). CONCLUSIONS: Alternative instruments, such as FRs, may be preferable to FFQs for evaluating diet-disease relationships in cohort studies. The results support a positive association between dietary fat and breast cancer.

Aged↗
PubMed2006

Interrelationships between serum leptin, IGF-1, IGFBP3, C-peptide and prolactin and breast cancer risk in young women.

Epidemiologic evidence suggests obese premenopausal women experience a reduced risk of breast cancer. The mechanism underlying this protection is not fully understood although it is well documented that abdominal obesity may impair ovulatory function and reduce gonadal steroidogenesis. We measured levels of several metabolic markers that are modified by obesity [measured by body mass index (BMI, (weight (kg)/height (m2)))] and play a role in the reproductive axis, including, leptin, insulin-like growth factor I (IGF-I), insulin-like growth factor binding protein 3 (IGFBP3), C-peptide and prolactin in 233 cases and 251 controls participating in a retrospective study of breast cancer in young women conducted in the Seattle/Puget Sound region between 1990 and 1992. Consistent with the finding of a reduced risk with increasing BMI, risks declined with leptin levels, although to a lesser degree with odds ratios (OR) for the highest vs. lowest quartile of BMI=0.34 (95% C.I. 0.3-0.8) and for leptin=0.71 (95% C.I. 0.5-1.3). IGF-I, IGFBP3, C-peptide and prolactin were not related to breast cancer risk in a dose-dependent manner. With the possible exception of leptin, our findings do not suggest that these markers explain the breast cancer protection provided by obesity in premenopausal women.

Adult↗
PubMed2006

Carotenoid and tocopherol estimates from the NCI diet history questionnaire are valid compared with multiple recalls and serum biomarkers.

To improve the measurement of usual dietary intake, the National Cancer Institute developed a cognitively based Diet History Questionnaire (DHQ), which has been validated against four 24-h dietary recalls (4 24-HR) for energy, macronutrients, and several vitamins and minerals. This analysis used data from The Eating at America's Table Study (EATS) to determine the validity of estimates for carotenoids and tocopherols from the DHQ. Over the course of a year, 163 participants provided 1 or 2 blood samples and completed the DHQ and 4 24-HR. For both the DHQ and the 4 24-HR, crude correlations between serum and diet were modest to strong for the provitamin A carotenoids (alpha-carotene, beta-carotene, beta-cryptoxanthin), low to modest for lycopene, and very low for lutein. The individual dietary tocopherols were weakly correlated with the serum tocopherols, but vitamin E from food and dietary supplements was strongly and positively correlated with serum alpha-tocopherol and strongly and inversely correlated with serum gamma-tocopherol for both instruments. Adjustment for energy, BMI, smoking status, serum total cholesterol, and serum triacylglycerol did not appreciably change the correlations. Using the method of triads, validity coefficients for the DHQ were comparable to the 4 24-HR and were especially strong for alpha-carotene, beta-cryptoxanthin, lutein + zeaxanthin, and total vitamin E in men and gamma-tocopherol and total vitamin E in women. In this study, there was no advantage of 2 blood samples over 1, suggesting reasonably stable ranking of individuals for these biomarkers, which is important for large epidemiologic studies that typically obtain only 1 blood sample for biomarker status.

Adult↗
PubMed2006

A debriefing session with a nutritionist can improve dietary assessment using food diaries.

The objective of the current study was to evaluate the effect of a debriefing call on nutrient intake estimates using two 3-d food diaries among women participating in the Women's Health and Interview Study (WISH) Diet Validation Study. Subjects were 207 women with complete data and six 24-h recalls (24-HR) by telephone over 8 mo followed by two 3-d food diaries during the next 4 mo. Nutrient intake was assessed using the food diaries before and after a debriefing session by telephone. The purpose of the debriefing call was to obtain more detailed information on the types and amounts of fat in the diet. However, due to the ubiquitous nature of fat in the diet, the debriefing involved providing more specific detail on many aspects of the diet. There was a significant difference in macronutrient and micronutrient intake estimates after the debriefing. Estimates of protein, carbohydrate, and fiber intake were significantly higher and total fat, monounsaturated fat, saturated fat, vitamin A, vitamin C, alpha-tocopherol, folic acid, and calcium intake were significantly lower after the debriefing (P < 0.05). The limits of agreement between the food diaries before and after the debriefing were especially large for total fat intake, which could be under- or overestimated by approximately 15 g/d. The debriefing call improved attenuation coefficients associated with measurement error for vitamin C, folic acid, iron, alpha tocopherol, vitamin A, and calcium estimates. A hypothetical relative risk (RR) = 2.0 could be attenuated to 1.16 for folic acid intake assessed without a debriefing but to only 1.61 with a debriefing. Depending on the nutrients of interest, the inclusion of a debriefing can reduce the potential attenuation of RR in studies evaluating diet disease associations.

Adult↗
PubMed2006

Dietary recommendations and identified research needs for The National Children's Study.

Many years of research have resulted in a set of accepted methods for dietary assessment of adult populations in large epidemiologic studies. Yet, relatively little has been done to develop and validate dietary methods for studies of pregnant and lactating women, infants, children, and adolescents. As plans for including dietary assessment in the National Children's Study (NCS) were developed, it became clear that complex methodological issues required further study and clarification. Along with validation of existing and new instruments, research is required to identify key dietary characteristics to be assessed at various stages of childhood and adolescence and how that information can best be collected. The types of instruments used, the mode of data collection (automated vs. nonautomated instruments), the timing of data collection, and differentiation between children and parents as respondents are areas requiring further inquiry. This paper presents the research needs identified through the process followed to provide the NCS with recommendations for the collection of dietary intake data.

Aging↗
PubMed2006

Maternal androgen and estrogen concentrations are not associated with blood pressure changes in uncomplicated pregnancies.

Systolic blood pressure increase between the second and third trimester of pregnancy has been associated with a substantially reduced maternal breast cancer risk, and it has been suggested that elevated androgens mediate the association. Androgen and estrogen concentrations were measured in maternal serum collected in 86 uncomplicated, singleton pregnancies. Overall, there were no consistent or statistically significant patterns of association between the hormones and systolic, diastolic, or mean arterial blood pressure or blood pressure change between trimesters. Results were similar with adjustment for factors related to the hormones. These data are not consistent with the hypothesis that elevated androgen concentrations mediate the observed reduction in maternal breast cancer risk associated with increases in blood pressure over the pregnancy.

Adult↗
PubMed2005

Pregnancy hormone concentrations across ethnic groups: implications for later cancer risk.

A variety of in utero factors have been associated with risk of adult cancers, particularly birth weight, toxemia, and gestational age. These factors are thought to reflect hormonal exposures during pregnancy. We hypothesized that the prenatal hormonal milieu may explain part of the variation in cancer rates across ethnic groups, for example, the higher incidence of breast cancer in the Caucasian compared with Hispanic women and the higher incidence of prostate and lower incidence of testicular cancers among African-Americans compared with Caucasians. We measured hormones in early pregnancy blood samples from three ethnic groups in a health care plan in Boston, MA. Mean levels of androstenedione, testosterone, estrone, and prolactin were significantly lower in Caucasian women compared with Hispanic women. Although not statistically significant, estradiol levels were lower in Caucasian compared with Hispanic or African-American women. Concentrations of androstenedione, testosterone, and progesterone were notably higher in African-American compared with Caucasian or Hispanic women. These data are consistent with hypotheses that in utero hormonal exposures may explain some of the ethnic group differences in cancer risk.

Adult↗
PubMed2004

Recall of physical activity in the distant past: the 32-year follow-up of the Prospective Population Study of Women in Göteborg, Sweden.

It has been of interest to researchers in chronic disease epidemiology to determine whether elderly subjects can accurately recall their physical activity patterns in the distant past. As part of a 32-year follow-up of the Prospective Population Study of Women in Göteborg, Sweden, 433 participants currently aged 70-92 years recalled their leisure-time physical activity at the original examination in 1968, when they had been 38-60 years of age. Using a four-point scale, subjects were originally asked to describe leisure-time activity during the previous 12 months. Identical questions were asked in 2000 describing levels in 1968 and current levels. Subjects were more likely to overestimate their previous activity level than to underestimate it: 43.9% of women classified themselves consistently at both examinations; 48.7% overestimated and 7.4% underestimated their previous activity levels. Using current activity as a proxy for recalled levels did not improve the moderate agreement with activity as originally reported in 1968. The average magnitude of the recall bias (recalled minus original values) amounted to one half of a unit on the four-point scale and was not significantly associated with age or body mass index. In summary, systematic errors were observed in remote physical activity recalls by elderly women, who generally remembered being more active 32 years earlier than they had originally reported. Physical activity recall questionnaires for the distant past should be used with caution, particularly in older populations.

Adult↗
PubMed2004

Serum levels of sex hormones and breast cancer risk in premenopausal women: a case-control study (USA).

High levels of serum estrogens and androgens have been convincingly linked with an increased risk of breast cancer among postmenopausal women. By contrast, the role of blood levels of these hormones in the etiology of premenopausal breast cancer is not well understood. In a case-control study, we sought to examine associations between levels of serum estradiol, sex-hormone binding globulin (SHBG), dehydroepiandrosterone (DHEA), testosterone, androstenedione and progesterone and risk of premenopausal breast cancer. Cases of breast cancer under age 45 were identified using rapid ascertainment systems in Seattle/Puget Sound, Washington and control subjects were identified from the same area through random digit dialing methods. A total of 169 eligible breast cancer cases and 195 control subjects donated blood (either before or six or more weeks after surgery) and were interviewed using a standardized questionnaire. The fully adjusted risk ratios and 95% confidence intervals for the highest versus lowest tertiles of estradiol, according to menstrual cycle phase, were 3.10 (0.8-12.7) for early follicular, 0.54 (0.2-1.7) for late follicular and 0.60 (0.3-1.4) for luteal. Risks for highest versus lowest quartiles of SHBG and androgens were 0.81 (0.4-1.6) for SHBG, 2.42 (1.1-5.2) for DHEA, 1.12 (0.6-2.5) for testosterone, and 1.33 (0.6-2.8) for androstenedione. For luteal progesterone, the RR for the highest versus lowest tertile was 0.55 (0.2-1.4). In summary, we did not find a convincing association between serum SHBG, estradiol, testosterone or androstenedione and premenopausal breast cancer risk. Observed differences between cases and controls subjects in serum levels of DHEA and luteal phase progesterone should be investigated further in large prospective studies.

Adult↗
PubMed2004

Relative validity of a food frequency questionnaire with a meat-cooking and heterocyclic amine module.

The nutrient and heterocyclic amine (HCA) intake of 165 healthy participants was assessed using a self-administered food frequency questionnaire (FFQ), which included a meat-cooking practices module. A database containing the HCA [2-amino-3,8-dimethylimadazo [4,5-f] quinoxaline (MeIQx) and 2-amino-1-methyl-6-phenylimadazo [4,5-b] pyridine (PhIP)] composition of various types of meat, cooked by different methods and to varying degrees, was developed and validated in conjunction with this module. The relative validity of dietary and HCA intake estimated by the FFQ was investigated using multiple food diaries (3 sets of 4 nonconsecutive day diaries completed over a 3-month period) as the reference method. Crude correlation coefficients of HCA intake assessed by the FFQ and food diaries were 0.43 [95% confidence interval (CI) 0.30-0.55] for MeIQx and 0.22 (95% CI 0.07-0.36) for PhIP intake. Deattenuated correlations were 0.60 (95% CI 0.49-0.69) and 0.36 (95% CI 0.22-0.49), respectively. Absolute MeIQx and PhIP intake was, however, underestimated by the FFQ (21.9 and 78.1 ng/day) compared with the food diaries (34.9 and 263.8 ng/day). The FFQ underestimated total red meat intake, the percentage of consumers, and the median intake of roast/baked and microwaved red meat. PhIP intake was severely underestimated by the FFQ and was most likely because of an underestimation of the percentage of people who cooked chicken using PhIP-producing cooking methods such as broiling and pan-frying. Additionally, the FFQ overestimated the percentage of consumers of baked chicken, a cooking method that produces less PhIP. In conclusion, although the FFQ and meat module underestimated absolute MeIQx and PhIP intake, its ability to rank individuals according to intake was acceptable.

Adult↗
PubMed2004

Insulin-like growth factors, insulin-like growth factor-binding proteins, and endometrial cancer in postmenopausal women: results from a U.S. case-control study.

OBJECTIVE: To assess whether circulating insulin-like growth factor-1 (IGF-1), IGF-2, insulin-like growth factor-binding protein-1 (IGFBP-1), or IGFBP-3 were associated with endometrial cancer in postmenopausal women. STUDY DESIGN: Between 1987 and 1990, we conducted a case-control study of 405 women with endometrial cancer and 297 matched population-based controls. This analysis included 174 postmenopausal cases and 136 controls. RESULTS: In logistic regression models adjusted for potential confounders, higher IGF-1 levels were not positively associated with endometrial cancer: odds ratio (OR) for the highest tertile versus the lowest tertile = 0.63, 95% confidence interval (CI) = 0.30-1.32. Endometrial cancer was inversely associated with IGF-2 (OR for the highest tertile = 0.35, 95% CI = 0.18-0.69) and IGFBP-3 (OR for the highest tertile = 0.40, 95% CI = 0.21-0.77), and not associated with IGFBP-1. CONCLUSION: Serum IGF-1, IGF-2, and IGFBP-3, but not IGFBP-1, were inversely associated with endometrial cancer in postmenopausal women. These associations and the potential role of the IGF system in endometrial proliferation and carcinogenesis warrant further research.

Adult↗
PubMed2004

Diet and melanoma in a case-control study.

BACKGROUND: Malignant melanoma has been one of the most rapidly increasing cancers within the United States with few modifiable risk factors. This study investigates risk related to dietary factors, which are potentially modifiable. METHODS: Newly diagnosed patients with melanoma (n = 502) were recruited from pigment lesion clinics and controls (n = 565) were recruited from outpatient clinics. To investigate the relationship between melanoma and dietary factors in this case-control study, study subjects were requested to complete a food frequency questionnaire, which assessed diet over the previous year. Using logistic regression, odds ratios (ORs) for melanoma were computed for nutrient and alcohol intake. RESULTS: Persons in high versus low quintiles of energy-adjusted vitamin D, alpha-carotene, beta-carotene, cryptoxanthin, lutein, and lycopene had significantly reduced risk for melanoma (ORs < or = 0.67), which remained after adjustment for presence of dysplastic nevi, education, and skin response to repeated sun exposure. Addition of micronutrients from supplements did not add an additional reduction in risk. High alcohol consumption was associated with an increased risk for melanoma, which remained after adjustment for confounders [OR (95% confidence interval) in highest versus lowest quintiles, 1.65 (1.09-2.49)]. CONCLUSIONS: Diets consisting of foods rich in vitamin D and carotenoids and low in alcohol may be associated with a reduction in risk for melanoma. These analyses should be repeated in large, prospective studies.

Adult↗
PubMed2003

Associations of maternal and umbilical cord hormone concentrations with maternal, gestational and neonatal factors (United States).

OBJECTIVE: Risks of some cancers in adults have been associated with several pregnancy factors, including greater maternal age and birth weight. For hormone-related cancers, these effects are hypothesized to be mediated through higher in utero estrogen concentrations. In addition, racial differences in pregnancy hormone levels have been suggested as being responsible for differences in testicular and prostate cancer risk by race. However, data on hormonal levels related to these characteristics of pregnancy are sparse, particularly those from studies of the fetal circulation. METHODS: Estrogen and androgen concentrations were measured in maternal and umbilical cord sera from 86 normal, singleton pregnancies. RESULTS: Birth size measures (weight, length and head circumference) were positively correlated with maternal estriol (r = 0.25-0.36) and with cord DHEAS concentrations (r = 0.24-0.41), but not with estrogens in cord sera. Maternal age was inversely correlated with maternal DHEAS, androstenedione and testosterone concentrations (r = -0.30, -0.25 and -0.30, respectively), but uncorrelated with estrogens in either the maternal or cord circulation. Black mothers had higher androstenedione and testosterone concentrations than white mothers, however, there were no racial differences in any of the androgens in cord sera. Cord testosterone concentrations were higher in mothers of male fetuses, while both maternal and cord concentrations of estriol were lower in these pregnancies. CONCLUSIONS: These data demonstrate associations between hormone concentrations and pregnancy factors associated with offspring's cancer risk, however, the hormones involved and their patterns of association differ by whether the maternal or fetal circulation was sampled. Hormone concentrations in the fetal circulation in this study are not consistent with the hypothesis that greater estrogen concentrations in high birth weight babies mediate the positive association with breast cancer risk observed in epidemiologic studies, or with the hypothesis that higher testosterone exposure in the in utero environment of black males explains their higher subsequent prostate cancer risk.

Adolescent↗
PubMed2003

Maternal serum oestrogen and androgen concentrations in preeclamptic and uncomplicated pregnancies.

BACKGROUND: Epidemiological studies show a substantially reduced risk of breast cancer in adult daughters of preeclamptic pregnancies, and modest risk reductions have been demonstrated for mothers also. Alterations in pregnancy hormone concentrations, particularly lower in utero exposure to oestrogen, are hypothesized to mediate this association. METHODS: Pregnancy hormone concentrations were measured in maternal sera collected at hospital admission for labour and delivery from 86 preeclamptic and 86 uncomplicated, singleton pregnancies matched on length of gestation, maternal age, parity, and type of delivery. RESULTS: Case and control pregnancies were similar in several maternal and pregnancy factors. Serum unconjugated oestradiol, oestrone, and oestriol concentrations were not lower in preeclamptic pregnancies in a matched analysis with adjustment for race and whether blood was collected before or after labour commenced. Serum unconjugated androstenedione (506.3 versus 316.0 ng/dl; P = 0.0007) and testosterone concentrations (214.5 versus 141.9 ng/dl; P = 0.004), however, were significantly higher in preeclamptic compared with control pregnancies, whereas dehydroepiandrosterone (DHEA) and DHEA sulphate did not differ. CONCLUSIONS: These data do not support the hypothesis that cancer risk in mothers and offspring of preeclamptic pregnancies is explained by exposure to lower maternal blood oestrogen concentrations, but raise the possibility that androgens play a role.

Adult↗
PubMed2003

Biologic and methodologic issues for nutritional biomarkers.

Nutritional biomarkers are used for a variety of purposes in large-scale population surveys and epidemiologic studies as well as smaller clinical studies. The main reasons for using nutritional biomarkers are to provide measures of nutritional status that have less error than dietary data, nutrient status for nutrients with inadequate dietary data, to obtain a more proximal and integrated assessment of nutrient status that incorporates metabolism, to assess dietary change and compliance in intervention studies, and dietary intake for the validation of dietary questionnaires. However, often there is oversight by the investigators regarding biologic and laboratory issues, which have implications for the utility of nutritional biomarkers. This article reviews some of the physiologic issues that contribute to between-person variability in nutrient status and the utility and meaning of specimens from various body compartments. Issues related to the collection and storage of biologic specimens are addressed, although it is recommended that investigators contact laboratory colleagues at the beginning of any study for updated information. The necessity for blind quality surveillance of laboratory analyses beyond the normal procedures employed by collaborating laboratories also is addressed. The advantages and disadvantages of nutritional biomarkers are reviewed, especially in comparison with using dietary methodology.

Absorption↗
PubMed2003

Correlation of serum hormone concentrations in maternal and umbilical cord samples.

Evidence suggests that adult cancer risk of hormonally related tumors may be influenced by the in utero environment, and most speculation on the biological mechanism has focused on the hormonal component. Epidemiological studies investigating the biological nature of pregnancy and maternal factors associated with offspring's cancer risk have relied on maternal hormone measurements. The degree to which maternal hormone levels represent the fetal environment, however, is not widely known. Pregnancy estrogen, androstenedione, testosterone, dehydroepiandrosterone (DHEA), and DHEA-sulfate concentrations were measured in maternal and mixed umbilical cord sera from 86 singleton pregnancies. Spearman correlations between maternal and cord hormone levels generally ranged between 0.2 and 0.3. The correlation was 0.26 for estriol, the estrogen of highest concentration in pregnancy, and 0.27 for estradiol, the most biologically active estrogen. The correlations between mother and offspring for the estrogens and DHEA appeared similar for males and females, whereas there was a suggestion that the maternal-umbilical cord correlations for other androgens varied in magnitude by fetal sex, and all correlations appeared higher in pregnancies lasting <38 weeks compared with longer gestational lengths, although these stratified findings may have been attributable to chance. These data show a moderate degree of correlation in hormone concentrations between the maternal and fetal circulation. Studies using maternal hormone concentrations as a proxy for the fetal environment should consider the misclassification resulting with the use of this marker.

Adult↗
PubMed2003

Estrogen and androgen concentrations are not lower in the umbilical cord serum of pre-eclamptic pregnancies.

Reductions in breast cancer risk observed in daughters of pre-eclamptic pregnancies are hypothesized to be mediated by lower in utero estrogen concentrations. Whereas maternal urinary estriol excretion is generally lower in pre-eclamptic women, results for maternal blood concentrations are equivocal, and little is known about estrogen concentrations in the cord of pre-eclamptic pregnancies. Unconjugated estrogen and androgen concentrations were measured in mixed umbilical cord sera from 86 pre-eclamptic and 86 uncomplicated, singleton pregnancies, matched on length of gestation, maternal age, parity, and type of delivery. Pre-eclamptic and uncomplicated pregnancies were similar in maternal age, prepregnancy weight, maternal height, type of delivery, use and type of anesthesia, and sex of offspring. Estriol, estradiol, estrone, dehydroepiandrosterone, dehydroepiandrosterone-sulfate, androstenedione, and testosterone concentrations measured in cord sera were not significantly different in pre-eclamptics compared with uncomplicated pregnancies. Estriol was 9% lower (P = 0.43), and all of the other hormones were actually higher in pre-eclamptics with testosterone and estradiol approaching statistical significance (P = 0.06 and P = 0.12, respectively). These data do not support the hypothesis that the lower breast cancer risk in daughters of pre-eclamptic pregnancies is explained by lower in utero estrogen exposure.

Adolescent↗