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Biomedical subjects

N Potischman

Publications and source records attributed to N Potischman.

At least 37 records · Page 2Linked to original sources
PubMed1998

Relationships of serum carotenoids, retinol, alpha-tocopherol, and selenium with breast cancer risk: results from a prospective study in Columbia, Missouri (United States)

To evaluate relationships of serum carotenoids, alpha-tocopherol, selenium, and retinol with breast cancer prospectively, we conducted a case-control study nested in a cohort from the Breast Cancer Serum Bank in Columbia, Missouri (United States). Women free of cancer donated blood to this bank in 1977-87. During up to 9.5 years of follow-up (median = 2.7 years), 105 cases of histologically confirmed breast cancer were diagnosed. For each case, two women alive and free of cancer at the age of the case's diagnosis and matched on age and date of blood collection were selected as controls. A nonsignificant gradient of decreasing risk of breast cancer with increasing serum beta-cryptoxanthin was apparent for all women. Serum lycopene also was associated inversely with risk, and among women who donated blood at least two years before diagnosis, a significant gradient of decreasing breast cancer risk with increasing lycopene concentration was evident. A marginally significant gradient of decreasing risk with increasing serum lutein/zeaxanthin also was apparent among these women. We did not observe any evidence for protective effects of alpha- and beta-carotene, alpha-tocopherol, retinol, or selenium for breast cancer. Results of this study suggest that the carotenoids beta-cryptoxanthin, lycopene, and lutein/zeaxanthin may protect against breast cancer.

Adult↗
PubMed1998

Cigarette smoking and breast cancer risk among young women (United States).

OBJECTIVES: To evaluate whether heavy cigarette smoking as a teenager or long-term smoking increases breast cancer risk or, alternatively, whether smoking acts as an anti-estrogen and reduces risk. METHODS: Data from a multi-center, population-based, case-control study among women under age 55 were analyzed. RESULTS: Among women under age 45, there was a modest inverse relation with current (OR = 0.82, 95% CI = 0.67, 1.01) but not past (OR = 0.99, 95% CI = 0.81, 1.21) smoking. Odds ratios were decreased for current smokers who began at an early age (0.59 for < or = 15, 95% CI = 0.41, 0.85) or continued for long periods of time (0.70 for >21 years, 95% CI = 0.52, 0.94). In subgroup analyses, reduced odds ratios were observed among current smokers who were ever users of oral contraceptives (0.79, 95% CI = 0.63, 0.98), were in the lowest quartile of adult body size (0.53, 95% CI = 0.34, 0.81), or never or infrequently drank alcohol (0.68, 95% CI = 0.47, 0.98). Among women ages 45-54, there was little evidence for an association with smoking. CONCLUSIONS: These results suggest that breast cancer risk among women under age 45 may be reduced among current smokers who began smoking at an early age, or long-term smokers, but require confirmation from other studies.

Adolescent↗
PubMed1998

Fertility problems and breast cancer risk in young women: a case-control study in the United States.

OBJECTIVES: Late age at first birth and nulliparity are established risk factors for breast cancer, yet the extent to which fertility problems contribute to these associations remains largely unexplored. Here, we examine self-reported fertility problems as a risk factor for breast cancer in young women. METHODS: We used a population-based case-control study of 2,173 cases and 1,990 controls aged 20 to 54 years in the United States. Structured in-person interviews were used to elicit detailed information on established and potential breast cancer risk factors. Information was collected on pregnancy details, including difficulties becoming pregnant or maintaining a pregnancy. RESULTS: Self-reported difficulty in becoming pregnant or maintaining a pregnancy was reported by 450 cases and 377 controls. Overall, there was little association between these fertility problems and risk of breast cancer (odds ratio [OR] = 1.05). Parity was associated with a decreased risk of breast cancer in women both with (OR = 0.71) and without (OR = 0.79) fertility problems. There was little evidence of an increased risk of breast cancer with later age at first full-term birth among women without fertility problems (ORage 35+ :age <20 = 1.13, 95 percent confidence interval [CI] = 0.7-1.9), but a relatively strong association among women with fertility problems (ORage 35+ :age <20 = 2.96, CI = 1.3-7.0). Among women with a first full-term birth at age 35 or older, fertility problems were associated with a twofold risk of breast cancer. Analyses of duration of unprotected sexual intercourse prior to first pregnancy as an alternative estimate of infertility produced similar results. CONCLUSIONS: Our study suggests that the association between late age at first birth and breast cancer is stronger among women with self-reported fertility problems than among women with no fertility problems.

Adult↗
PubMed1998

A nested case-control study of dietary factors and the risk of incident cytological abnormalities of the cervix.

Several earlier case-control studies reported inverse associations of cervical squamous intraepithelial lesions (SIL) with high dietary or biomarker levels of carotenoids, folate, and vitamins C and E. However, most studies did not measure the primary causal factor, cancer-associated genital human papillomaviruses (HPV), now detected by sensitive viral DNA tests. This nested case-control study assessed whether high dietary intakes of these nutrients, plus zinc and vitamin A, reduced SIL risk in cancer-associated HPV DNA-positive women. Using a 60-item food-frequency questionnaire, nutrient estimates were obtained for 33 incident cases with high-grade lesions, 121 with low-grade lesions, 97 with equivocal SIL, and 806 cytologically normal controls sampled from a large prospective cohort study. Baseline cervicovaginal lavages were tested for HPV DNA by the polymerase chain reaction. Among DNA-positive cases (n = 68) and controls (n = 69), age-adjusted odds ratios (ORs) of SIL in the highest vs. the lowest nutrient quartiles were 1.4 [95% confidence interval (CI) = 0.5-4.2] for vitamin A, 0.6 (CI = 0.2-2.0) for beta-carotene, 1.3 (CI = 0.4-3.6) for vitamin C, 1.0 (CI = 0.4-3.6) for vitamin E, 0.7 (CI = 0.3-2.1) for folate, and 0.8 (CI = 0.3-2.2) for zinc. ORs in HPV DNA-negative women approximated 1.0, with the exception of vitamin E (OR = 0.5, CI = 0.3-0.9). These results do not support a protective role for the above nutrients against low-grade or equivocal SIL, which constituted the majority of diagnoses in this study.

Adult↗
PubMed1998

Breast cancer risk among women under 55 years of age by joint effects of usage of oral contraceptives and hormone replacement therapy.

OBJECTIVE: To assess effects on breast cancer risk of exposure to both oral contraceptives and menopausal hormones, an increasingly common exposure. DESIGN: A case-control study of breast cancer among women under the age of 55 years in Atlanta, GA involving 1,031 cases and 919 population controls was conducted. RESULTS: Ever use of oral contraceptives was associated with a relative risk of 1.1 (95% 0.9-1.4), whereas the relative risk for hormone replacement therapy was 0.9 (95% CI 0.7-1.2). Seventeen percent of the cases versus 19% of the population controls reported exposure to both agents, resulting in a relative risk of 1.0 (95% CI 0.7-1.4) relative to those unexposed to either preparation. Although there was little variation in risk associated with joint effects by either age or race, there were statistically nonsignificant elevations in risk for this exposure among women who had experienced a natural menopause (relative risk = 2.0, 95% CI 0.7-5.6), were relatively thin (relative risk = 1.5, 0.8-3.0), or who had a first degree relative with breast cancer (relative risk = 2.0, 0.6-7.0). When joint effects of longer term use of both agents were considered, subjects who reported use of oral contraceptives for 10 or more years and hormone replacement for 3 or more years had a relative risk of 3.2 (95% CI 1.4-7.4) compared with nonusers of either preparation. CONCLUSIONS: Although our results must be cautiously interpreted given small numbers within subgroups, they raise concern and emphasize the need for further evaluation on breast cancer risk of the increasingly common exposure to both oral contraceptives and hormone replacement therapy.

Adult↗
PubMed1998

Pregnancy characteristics and maternal risk of breast cancer.

In a population-based case-control study of parous women less than 45 years of age, we evaluated the relations of various pregnancy characteristics to maternal breast cancer risk. Cases (N = 1,239) diagnosed with in situ or invasive breast cancer from 1990 to 1992 in Atlanta, GA, Seattle/Puget Sound, WA, and five counties in central New Jersey, and population controls (N = 1,166) identified by random-digit dialing, were interviewed regarding the details of their pregnancies. We used logistic regression to estimate relative risks (RR) and 95% confidence intervals (CI) and to adjust for breast cancer risk factors. Women who reported nausea or vomiting in their first pregnancy had a slightly lower risk of breast cancer (RR = 0.87; 95% CI = 0.72-1.0). We found no strong or consistent associations for maternal risk related to gestational length, pregnancy weight gain, gestational diabetes, pregnancy hypertension, or gender of the offspring, although we found some evidence for reductions in risk for toxemia (RR = 0.81; 95% CI = 0.61-1.1) and specific sex (RR for female twins vs singletons = 0.48; 95% CI = 0.20-1.3) and timing characteristics of twinning. Overall, these data provide little support for the hypothesis that pregnancy hormone levels are associated with subsequent maternal risk of breast cancer in young women.

Adult↗
PubMed1997

Insulin and endometrial cancer.

Elevated insulin levels may explain part of the increased risk of endometrial cancer observed in obese postmenopausal women. Circulating sex hormones and fasting C-peptide levels were measured in sera obtained from 165 postmenopausal endometrial cancer cases accrued between June 1, 1987, and May 15, 1990, from hospitals in Chicago, Illinois; Hershey, Pennsylvania; Irvine and Long Beach, California; Minneapolis, Minnesota; and Winston-Salem, North Carolina, and 180 community and hysterectomy controls. Women with a personal history of diabetes were excluded. Among controls, C-peptide was positively correlated with body mass index (BMI) ((r = 0.44), waist-to-thigh circumference ratio ((r = 0.24), estrone ((r = 0.18), and estradiol ((r = 0.28) (albumin-bound (r = 0.45), and free (r = 0.37)) and negatively correlated with sex hormone-binding globulin (r = -0.48). In age-adjusted analyses, the odds ratios and 95% confidence intervals for tertiles of C-peptide and endometrial cancer were, from lowest to highest: 1.0 (reference), 0.78 (95% confidence interval (CI) 0.43-1.4), and 2.2 (95% CI 1.3-3.7). Further adjustment for BMI substantially attenuated the odds ratios for the highest tertile of C-peptide (odds ratio = 1.2, 95% CI 0.63-2.1), and adjustment for body mass index and other risk factors for endometrial cancer eliminated the association (odds ratio = 1.0, 95% CI 0.55-2.0). In contrast, adjustment for C-peptide had little influence on the magnitude of the positive associations between body mass index (odds ratio for highest vs. lowest tertile, without and with adjustment for C-peptide = 4.1 (95% CI 2.3-7.5) and 3.7 (95% CI 1.9-7.1), respectively) or several steroid hormones and endometrial cancer. These data are not consistent with the hypothesis that the effect of obesity on endometrial cancer risk is mediated through high insulin levels.

Adult↗
PubMed1997

Dietary relationships with early onset (under age 45) breast cancer in a case-control study in the United States: influence of chemotherapy treatment.

Methodologic investigations have addressed selection and recall bias in case-control studies of diet and breast cancer, whereas the effect of disease progression and medical treatment on estimates of dietary intake has been largely overlooked. In a multicenter, population-based case-control study of breast cancer in the United States, 1,588 newly diagnosed cases and 1,451 controls completed a self-administered food-frequency questionnaire. Initial evaluation suggested increased risk related to high intakes of calories, carbohydrates, fat, and protein. All nutrient associations were diminished after adjustment for calories. Evaluation by stage of disease revealed no relation of calories to risk among women with in situ disease, but elevated risks among women with localized (odds ratio [OR] = 1.33, 95 percent confidence interval [CI] = 1.0-1.7 highest cflowest quartile) or regional and distant disease (OR = 1.79, CI = 1.3-2.4). Further evaluation showed that the increased risk associated with calories was restricted to cases who reported having been treated with chemotherapy (OR = 1.66, CI = 1.3-2.1). A gradient of increasing risk with time interval from diagnosis to interview suggested the chemotherapy regimen itself and not necessarily characteristics of tumors requiring this treatment was responsible for the observed increased risk. These results indicate that epidemiologic studies of diet and breast cancer, particularly among young women, should evaluate possible bias related to post-diagnosis influences.

Adult↗
PubMed1997

Alcohol consumption and breast cancer risk among women under age 45 years.

In a population-based case-control study of women younger than 45 years of age, we obtained a detailed lifetime history of alcohol use to evaluate the effects of drinking during different periods of life in relation to breast cancer risk. This analysis focused on interviews obtained from 1,645 cases and 1,497 controls. Breast cancer risk was not influenced by drinking during the teenage years or early adulthood. Contemporary drinking (that is, average intake during the recent 5-year interval) was directly associated with risk, but the adverse effect of recent drinking was restricted to women who consumed > or = 14 drinks per week [relative risk (RR) = 1.7; 95% confidence interval (CI) = 1.2-2.5]. The effect of alcohol was most pronounced among women with advanced disease. Compared with nondrinkers, the risk estimate associated with recent consumption of > or = 14 drinks per week was 2.4 (95% CI = 1.6-3.8) for women with regional/distant disease. Our data add support to the accumulating evidence that alcohol consumption is associated with increased risk of breast cancer and further indicate that alcohol acts at a late stage in breast carcinogenesis.

Adult↗
PubMed1997

Assay reproducibility of hormone measurements in postmenopausal women.

As part of a breast cancer case-control study of serum hormones conducted in Columbia, MO, we included several replicate quality control samples to monitor the consistency of laboratory assays. Sera were obtained from three postmenopausal women; from each woman, three samples were placed randomly in each of nine batches with the laboratory unaware of which sample corresponded to whom. Laboratory assays for estrone (E1), estradiol (E2), testosterone, androstenedione (Adione), E1SO4, dehydroepiandrosterone sulfate (DHEAS), follicle-stimulating hormone (FSH), sex hormone binding globulin (SHBG), and percentages of free and albumin-bound E2 were done at a single academic facility. ANOVA results showed that hormone values varied considerably from one batch to the next. The overall coefficients of variation (CVs) estimated for E2, percentage of unbound E2, and percentage of albumin-bound E2 were higher than 15%, but of these, only percentage of unbound E2 had both inter- and intra-assay CVs greater than 10%. Intraclass correlations (ICC) for FSH, SHBG, and DHEAS were high, suggesting that these assays are suitable for population-based studies attempting to link hormone levels to disease risk. The ICC estimated for E1SO4 was quite low due to aberrant values reported in a single batch. For the remaining hormones, the ICCs were fair (ranging from 47% for albumin-bound E2 to 67% for Adione), and studies using these assays would require a substantial increase in the sample size to detect small case-control differences.

Analysis of Variance↗
PubMed1997

Risk factors and hormone levels in patients with serous and endometrioid uterine carcinomas.

We performed a multi-institutional, incident case-control study of 328 endometrioid and 26 serous carcinomas to assess whether risk factors and circulating hormone levels in women with serous carcinoma differ from the expected profile for endometrial carcinoma We also evaluated exposures potentially related to endometrial cancer risk, anthropometric measurements, and circulating levels of sex hormones and related carrier proteins. Histopathologic specimens were reviewed without knowledge of the other data. As expected, a statistically significant association was observed for high body mass index (BMI) (relative risk, 3.5) and use of menopausal estrogens (relative risk, 2.4) in the endometrioid carcinoma cases, whereas serous carcinomas were not strongly associated with these factors. Smoking and oral contraceptive use decreased risk for both tumor types. For five of six sex hormones tested, age-adjusted mean serum levels in patients with serous carcinoma were significantly lower than those in women with endometrioid carcinoma. After adjustment for BMI, these differences were narrowed, but levels of albumin-bound estradiol and estrone remained significantly lower in the serous cases. Age and BMI-adjusted levels of sex hormone-binding globulin were significantly higher in patients with serous carcinoma than in women with endometrioid carcinomas. In conclusion, risk factors and sex hormone levels in patients with uterine serous carcinoma seem to differ from those in women with endometrioid carcinoma, suggesting that there may be at least two different pathways of endometrial carcinogenesis.

Age Factors↗
PubMed1996

Case-control study of endogenous steroid hormones and endometrial cancer.

BACKGROUND: It has been suggested that identified risk factors for endometrial cancer operate through a single etiologic pathway, i.e., exposure to relatively high levels of unopposed estrogen (estrogen in the absence of progestins). Only a few studies, however, have addressed this issue directly. PURPOSE: We assessed the risk of developing endometrial cancer among both premenopausal and postmenopausal women in relation to the circulating levels of steroid hormones and sex hormone-binding globulin (SHBG). The independent effect of hormones was assessed after adjustment for other known risk factors. METHODS: The data used in the analysis are from a case-control study conducted in five geographic regions in the United States. Incident cases were newly diagnosed during the period from June 1, 1987, through May 15, 1990. The case patients, aged 20-74 years, were matched to control subjects by age, race, and geographic region. The community control subjects were obtained by random-digit-dialing procedures (for subjects 20-64 years old) and from files of the Health Care Financing Administration (for subjects > or = 65 years old). Additional control subjects who were having a hysterectomy performed for benign conditions were obtained from the participating centers. Women reporting use of exogenous estrogens or oral contraceptives within 6 months of interview were excluded, resulting in 68 case patients and 107 control subjects among premenopausal women and 208 case patients and 209 control subjects among postmenopausal women. The hormone analyses were performed on blood samples obtained from case patients or from hysterectomy control subjects before surgery. The odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by use of an unconditional logistic regression analysis after we controlled for matching variables and potential confounders. All P values were two-sided. RESULTS: High circulating levels of androstenedione were associated with 3.6-fold and 2.8-fold increased risks among premenopausal and postmenopausal women, respectively, after adjustment for other factors (P for trend = .01 and < .001, respectively). Risks related to other hormone fractions varied by menopausal status. Among postmenopausal women, a reduced risk was associated with high SHBG levels and persisted after adjustment was made for obesity and other factors (OR = 0.51; 95% CI = 0.27-0.95). High estrone levels were associated with increased risk (OR = 3.8; 95% CI = 2.2-6.6), although adjustment for other risk factors (particularly body mass index) diminished the effect (OR = 2.2; 95% CI = 1.2-4.4). Albumin-bound estradiol (E2), a marker of the bioavailable fraction, also remained an important risk factor after adjustment was made for other factors (OR = 2.0; 95% CI = 1.0-3.9). In contrast, high concentrations of total, free, and albumin-bound E2 were unrelated to increased risk in premenopausal women. In both premenopausal and postmenopausal groups, risks associated with obesity and fat distribution were not affected by adjustment for hormones. CONCLUSION: High endogenous levels of unopposed estrogen are related to increased risk of endometrial cancer, but their independence from other risk factors is inconsistent with being a common underlying biologic pathway through which all risk factors for endometrial cancer operate. IMPLICATIONS: Further research should focus on alternative endocrinologic mechanisms for risk associated with obesity and body fat distribution and for the biologic relevance of the increased risk associated with androstenedione in both premenopausal and postmenopausal disease.

Adult↗
PubMed1996

Nutrition and cervical neoplasia.

Epidemiologic evidence on the relation between nutrition and cervical cancer is reviewed. Cervical cancer is the leading cancer among women in many developing countries, and remains a major public health problem worldwide. This review of nutritional research on cervical neoplasia encompasses the range of epithelial abnormalities from early preneoplastic lesions to invasive cancer. Identified risk factors for cervical neoplasia suggest a multifactorial etiology with several cancer-associated human papillomaviruses (HPV) as the central cause. Studies of nutritional predictors of cervical neoplasia to date, however, have been limited by inadequate HPV measures, which compromise the interpretations of findings. Current research using accurate measures of HPV will be most revealing. Nonetheless, agreement in findings from previous studies suggest a role for nutritional factors in some or all stages of cervical neoplasia. Low vitamin C and carotenoid status are associated fairly consistently with both cervical cancer and precursors, whereas results for vitamin E status are less consistent. The effect of folate status may be restricted to early preneoplastic cervical lesions and not to more advanced disease. Current research is addressing nutritional influences on HPV infection and persistence and on progression of cervical disease. Limitations and recommendations for future research directions are discussed in light of methodologic issues related to nutritional and HPV research.

Ascorbic Acid↗
PubMed1995

Improving food frequency questionnaires: a qualitative approach using cognitive interviewing.

In an attempt to improve data quality and ease of administration of standard self-administered food frequency questionnaires, various alternative approaches were tried for inquiring about frequency of consumption, portion size, seasonal intake, and food preparation. Evaluation consisted of a cognitive interviewing method in which respondents verbalize their thought process while completing several variations of a questionnaire. Interviewers observed and asked follow-up probe questions to evaluate problems or inconsistencies verbalized by respondents. Consensus and judgment by interviewers and observers suggested several problematic features of food frequency questionnaires: formatting of questions about frequency and portion size; computing average frequencies for aggregated food items or for foods eaten seasonally; comprehension of many items; and ordering of foods. These findings led to cognitive refinement and innovations, which included detailed questions regarding preparation or use of low-fat varieties or other alternatives to help better describe specifics of intake for some foods; questions on seasonal intake for several foods; inclusion of portion size ranges; and additional response categories for frequency of intake. Cognitive interviewing is an important step in pinpointing cognitive problems in dietary questionnaires.

Aged↗
PubMed1995

Diet and cancer: future etiologic research.

In light of several credible diet and cancer hypotheses, we suggest strategies for advancing our understanding in this area. Two conceptual approaches can be taken in defining dietary exposure: the decompositional approach focuses on specific nutrients and other chemical constituents of food, whereas the integrative approach emphasizes the action of whole foods or food patterns (cuisines). Diet-cancer hypotheses can be organized according to this conceptual framework. We review four types of scientific investigation available to us for advancing the diet and cancer field: metabolic (clinical nutrition) studies; animal studies; observational epidemiologic investigations; and clinical trials. Each of these designs has its strengths and limitations. Observational epidemiologic studies and trials have the particular advantage of examining explicit cancer end points in humans. Results from metabolic and animal research, however, can complement the findings from epidemiologic studies and trials. Finally, we briefly review strategies for evaluating promising hypotheses linking diet to cancers of the large bowel, lung, breast, and prostate.

Animals↗
PubMed1994

Reproducibility of laboratory assays for steroid hormones and sex hormone-binding globulin.

The relationship of serum hormones to cancer risk has recently been pursued in epidemiological studies, but few have reported on the reproducibility of laboratory findings. Prior to conducting a study of endogenous hormones and endometrial cancer, we evaluated the reproducibility of measurements for several hormones (estrone, estradiol, free estradiol, albumin-bound estradiol, and androstenedione) and sex hormone-binding globulin. We obtained a single unit of blood from each of six women and prepared aliquots of serum for repeated testing. Three laboratories analyzed multiple samples on consecutive working days from which estimates of intraassay and interassay measurement variability were obtained. For estrone and estradiol, a log transformation of the data produced distributions which were nearly normal and permitted the use of parametric statistical tests. In general, we found measurements for most hormones varied considerably between assays. Moreover, differences were observed in the absolute values of sex hormone-binding globulin and of the hormones, particularly for estrone and estradiol, from one laboratory to the next. Our findings suggest that variability of current laboratory procedures may hamper efforts to study the association between disease and endogenous hormones in epidemiological studies. In addition, validation of hormone assays is essential in order to assure standardized results and enable comparisons of data across studies.

Androstenedione↗