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Biomedical subjects

K Helzlsouer

Publications and source records attributed to K Helzlsouer.

18 recordsLinked to original sources
PubMed2001

Breast cancer epidemiology, prevention, and early detection.

Breast cancer remains a worldwide public health concern despite the fact that mortality rates have been declining in some countries as a result of improvements in adjuvant therapy and screening for breast cancer. In the prevention arena, advances in our understanding of the effects of tamoxifen have led to the investigations of newer agents that may provide extended options for breast cancer prevention in high-risk women. For women who are carriers of a mutation in the breast cancer susceptibility genes BRCA1 or BRCA2, prophylactic oophorectomy and bilateral mastectomy have emerged as preventative surgical options that can significantly impact breast cancer risk. In addition, the identification of potentially modifiable risk factors for breast cancer such as dietary folate intake, alcohol consumption, physical activity, and certain anthropometric factors provides opportunities for intervening in breast cancer prevention both among women at average and high risk. The challenge remains in overcoming the limitations of mammography and clinical breast examination by developing and evaluating new technologies for breast cancer screening such as digital mammogram and breast magnetic resonance imaging.

Breast Neoplasms↗
PubMed2000

Use of hair dyes, hematopoietic neoplasms, and lymphomas: a literature review. I. Leukemias and myelodysplastic syndromes.

We review published epidemiologic studies on personal use of hair dyes and leukemias and myelodysplastic syndromes (MDS). A subsequent article will review studies on lymphomas and multiple myeloma. A computerized literature search for the years 1966 through 1996 was completed using MEDLINE. Data were extracted using a standardized form that recorded study design, study population, type of cases, comparison group, sources of data on personal exposure to hair dyes, method of data collection, type of exposure data collected, covariates, and results. The above search identified 13 epidemiologic studies on the possible association between personal use of hair dyes and leukemias and MDS. Although there are some reports of positive associations, overall the evidence linking personal use of hair dyes to various leukemia and MDS subgroups is weak. One cannot definitively rule out an association, however, because of the methodologic limitations, such as small numbers of exposed cases and lack of detailed exposure information. Any further research would need much better assessment of hair dye use, including product type, color frequency, duration, and changes in use over time, and adequate statistical power.

Case-Control Studies↗
PubMed2000

Use of hair dyes, hematopoietic neoplasms, and lymphomas: a literature review. II. Lymphomas and multiple myeloma.

We review studies on hair dyes and lymphomas and multiple myeloma (MM). A computerized literature search for the years 1966 through 1996 was conducted. Data were extracted using a standardized form that recorded study design, study population, type of cases, comparison group, sources of data on personal exposure to hair dyes, method of data collection, type of exposure data collected, covariates, and results. This review identified 10 epidemiologic studies published in the English literature that examined personal use of hair dyes and lymphomas or MM. These studies include three evaluations of Hodgkin's disease, five of non-Hodgkin's lymphoma (NHL), two of lymphomas with type not specified, and six of MM. For Hodgkin's disease, one case-control study reported some positive associations with use of permanent hair dyes, whereas two cohort studies found no associations with ever use of hair dyes. For NHL and MM, several evaluations suggest associations with use of permanent dyes, particularly with duration, frequency, age at first use, and dark colors. However, these associations are not consistent within and between studies. For lymphomas with type not specified, one study was superseded by a more recent report with NHL specific data and a second study was limited by small numbers of exposed subjects. At this time, it is not possible to determine if the inconsistent associations between permanent hair dyes and NHL and MM reflect sampling variability or differences in methods between studies. Because an appreciable fraction of the population has potential exposure to permanent hair dyes, elucidation of such issues may be warranted with studies that include adequate numbers of exposed subjects and that elicit information on personal use of hair dyes over time.

Case-Control Studies↗
PubMed1999

Weighing the risks and benefits of tamoxifen treatment for preventing breast cancer.

BACKGROUND: In response to findings from the Breast Cancer Prevention Trial that tamoxifen treatment produced a 49% reduction in the risk of invasive breast cancer in a population of women at elevated risk, the National Cancer Institute sponsored a workshop on July 7 and 8, 1998, to develop information to assist in counseling and in weighing the risks and benefits of tamoxifen. Our study was undertaken to develop tools to identify women for whom the benefits outweigh the risks. METHODS: Information was reviewed on the incidence of invasive breast cancer and of in situ lesions, as well as on several other health outcomes, in the absence of tamoxifen treatment. Data on the effects of tamoxifen on these outcomes were also reviewed, and methods were developed to compare the risks and benefits of tamoxifen. RESULTS: The risks and benefits of tamoxifen depend on age and race, as well as on a woman's specific risk factors for breast cancer. In particular, the absolute risks from tamoxifen of endometrial cancer, stroke, pulmonary embolism, and deep vein thrombosis increase with age, and these absolute risks differ between white and black women, as does the protective effect of tamoxifen on fractures. Tables and aids are developed to describe the risks and benefits of tamoxifen and to identify classes of women for whom the benefits outweigh the risks. CONCLUSIONS: Tamoxifen is most beneficial for younger women with an elevated risk of breast cancer. The quantitative analyses presented can assist health care providers and women in weighing the risks and benefits of tamoxifen for reducing breast cancer risk.

Age Factors↗
PubMed1997

A nested case-control study of non-Hodgkin lymphoma and serum organochlorine residues.

BACKGROUND: The steady worldwide increase in the incidence of non-Hodgkin lymphoma during the past few decades remains mostly unexplained. Several studies suggest that there may be an association between the agricultural use of the organochlorine 1,1,1-trichloro-2,2'bis(p-chlorophenyl)ethane (DDT) and increased risk of non-Hodgkin lymphoma. We have investigated the association between risk of non-Hodgkin lymphoma and body burden of selected organochlorines in the general population in a nested case-control study. METHODS: We measured prediagnostic serum concentrations of DDT, its metabolites, and other organochlorines, including polychlorinated biphenyls (PCBs), in 74 cases of non-Hodgkin lymphoma and 147 matched controls identified from a prospective cohort of 25,802 adults, established in 1974 in Washington County, Maryland, USA. We report results for total lipid-corrected serum concentrations of DDT and total PCBs. FINDINGS: There was a strong dose-response relation between quartiles of total lipid-corrected serum PCB concentrations and risk of non-Hodgkin lymphoma overall (odds ratios by quartile: 1.0; 1.3 [95% CI 0.5-3.3]; 2.8 [1.1-7.6]); and 4.5 [1.7-12.0]; p for trend = 0.0008) and separately in men and in women. There was also evidence suggesting that seropositivity for the Epstein-Barr virus early antigen potentiated the effects of serum PCBs. By contrast, total lipid-corrected serum concentrations of DDT were not associated with risk of non-Hodgkin lymphoma. INTERPRETATION: These results should be regarded as hypothesis-generating. Before causal inferences can be made about exposure to PCBs and increased risk of non-Hodgkin lymphoma, our findings require replication and the biological plausibility of the association needs further investigation.

Adult↗
PubMed1997

Serum levels of vitamin D metabolites and the subsequent risk of colon and rectal cancer in Finnish men.

Experimental and human epidemiologic data suggest a protective role for vitamin D in large bowel cancer. To investigate this association, we conducted a nested case-control study within a Finnish clinical trial cohort. Cases (n = 146) were participants diagnosed with primary adenocarcinoma of the large bowel. Controls were matched (2:1) to cases on age, date of baseline blood draw, and study clinic. Prediagnostic serum levels of the vitamin D metabolites, 25-hydroxyvitamin D (25-OH D), and 1,25-dihydroxyvitamin D (1,25-DIOH D) were used as primary exposure measures. The baseline geometric-mean serum level of 25-OH D was 11.6 percent lower in cases than in controls (12.2 cf 13.8 ug/l, P = 0.01) while serum levels of 1,25-DIOH D did not differ by case-control status. No association was seen between serum levels of 1,25-DIOH D and large bowel cancer risk. However, the estimated relative risk (RR) of large bowel cancer decreased with increasing level of serum 25-OH D and the association was more pronounced for rectal cancer (55 cases; RR by quartile = 1.00, 0.93, 0.77, 0.37; trend P = 0.06). Neither exclusion of early cases nor multivariate adjustment for potential confounders materially altered these estimates. There was no evidence of effect modification by level of 1,25-dihydroxyvitamin D or with other known risk-factors for large bowel cancer.

Adenocarcinoma↗
PubMed1995

Cancer prevention behaviors among African-American adults: a survey of wards 7 and 8 in Washington, DC.

A telephone survey of knowledge, attitude, and health practices regarding cancer was undertaken in wards 7 and 8, Washington, DC in 1988. These wards have the highest cancer rates in the city and are predominantly African American. Of the 670 randomly selected persons over 18 years of age, 243 were males and 427 were females. Among females, 84% believed cigarette smoking causes cancer, and 48% thought alcohol causes cancer; 31% smoked cigarettes and 38% consumed alcoholic beverages. Among males, 91% and 52% thought cigarettes and alcohol causes cancer respectively; 41% smoked and 54% consumed alcoholic beverages. Only 6% of the males over age 40 practiced all eight recommended cancer prevention behaviors, while 2% of the females over age 40 practiced all preventive health behaviors. Cancer preventive behavior was examined in relation to socioeconomic status. This study indicates that preventive health behaviors were not associated with socioeconomic status. Data suggest that cancer prevention and control programs and services targeted to this Washington, DC population should be increased and intensified.

Adolescent↗
PubMed1992

Inherited p53 gene mutations in breast cancer.

Recent evidence has implicated germ-line mutations of the p53 gene as the cause of cancer susceptibility in the Li-Fraumeni syndrome, associated with the development of breast cancer and other neoplasms. Furthermore, somatic mutations of the p53 gene have been detected in a high percentage of non-familial breast cancers. We therefore sought to identify potential carriers of p53 gene mutations in a cohort of patients with early onset breast cancer. We examined 126 consecutive patients who developed breast cancer at or before the age of 40 for mutations of p53 within conserved regions of the gene. One patient with an inherited germ-line mutation of the p53 gene was identified but the functional significance of this mutation was not clear. It thus appears that only a small percentage of patients with breast cancer under the age of 40 carry germ-line mutations of the p53 gene, an observation which has implications for potential screening and risk assessment in such patients.

Adult↗
PubMed1992

Serum retinol, beta-carotene, vitamin E, and selenium as related to subsequent cancer of specific sites.

Case-control differences in prediagnostic serum levels of retinol, beta-carotene, vitamin E, and selenium are compared for 10 cancer sites in 10 study populations. For all four nutrients, the majority of results showed lower levels among persons who subsequently became cases than among controls. Low levels of beta-carotene were most likely to be associated with subsequent cancer, but there were marked differences by cancer site. The results indicate that it is unlikely that any of these serum micronutrients are associated with protection against carcinogenesis at all sites. A plea is made for greater emphasis on replication of results, for reporting findings for all sites no matter how small the number of cases may be, and for keeping constantly in mind the fact that observational associations are not necessarily causal in nature.

Antioxidants↗
PubMed1992

Mechanisms of chemoprotection by oltipraz.

1,2-Dithiole-3-thiones are five-membered cyclic sulfur-containing compounds with antioxidant, chemotherapeutic, radioprotective and cancer chemoprotective properties. One substituted dithiolethione, oltipraz [5-(2-pyrazinyl)-4-methyl-1,2-dithiole-3-thione], originally developed as an antischistosomal agent, has recently been observed to protect against chemically induced carcinogenesis in lung, trachea, forestomach, colon, breast, skin, liver and urinary bladder in rodents. The induction of electrophilic detoxication enzymes, which result in diminished carcinogen-DNA adduct formation and reduced cytotoxicity, appears to be an important component of the anticarcinogenic action of oltipraz and other dithiolethiones. Phase I trials of oltipraz are presently underway in the United States. Subsequent trials might be most appropriately targeted towards individuals at high risk for occupational or environmental exposures to genotoxic carcinogens.

Animals↗
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↗
PubMed1989

Human selenite metabolism: a kinetic model.

A model is developed to describe the kinetics of sodium selenite metabolism in humans, based on plasma, urine, and fecal samples obtained from six subjects over a 4-wk period after a single oral 200-micrograms dose of the enriched stable isotope tracer 74Se. The model describes absorption, distributed along the gastrointestinal tract, and enterohepatic recirculation. The model includes four kinetically distinct plasma components, a subsystem consisting of the liver and pancreas, and a slowly turning-over tissue pool. For the six subjects, the ranges of mean residence times for the four plasma components are, respectively, 0.2-1.1 h, 3-8 h, 9-42 h, and 200-285 h; for the hepatopancreatic subsystem 4-41 days; and for the tissue pool 115-285 days. Approximately 84% of the administered dose was absorbed, and after 12 days approximately 65% remained in the body. The model predicts that after 90 days approximately 35% of this Se would be retained, primarily in the tissues. Separating Se metabolism into several distinct kinetic components is a first step in identifying the efficacious, nutritious, and toxic forms of the element.

Feces↗
PubMed1986

Acute myocardial infarction among Navajo Indians, 1976-83.

We found that from 1976 through 1983 the incidence of acute myocardial infarction (AMI) diagnosed among Navajo Indians remained low (0.5 per 1,000 persons age 30 years or more), although the incidence in women appears to be climbing. Navajo AMI patients are more likely to be hypertensive and diabetic than age- and sex-matched patients with gallbladder disease. Twenty-four per cent die within one month of AMI.

Adolescent↗
PubMedDate not supplied

The impact of a brief coping skills intervention on adherence to breast self-examination among first-degree relatives of newly diagnosed breast cancer patients.

The present investigation sought to determine (1) the impact of a single session stress management/coping intervention (problem-solving training; PST) versus a general health counseling (GHC) control condition on breast self-examination (BSE) adherence among relatives of newly diagnosed breast cancer patients, and (2) whether women with heightened perceived risk of breast cancer and/or cancer specific distress at baseline were more likely to improve their BSE adherence following PST. The participants were 510 women age 20-75 who had at least one first-degree relative with breast cancer. All of the participants completed a baseline telephone interview, an intervention (PST versus GHC), and a 3-month follow-up telephone interview. The results revealed a 36% overall improvement in BSE adherence, with no significant between-group difference in improvement (chi 2 = 0.03, p = 0.87). The logistic regression analysis of improvement in BSE adherence revealed a statistically significant cancer-specific distress by treatment interaction (p = 0.04). Among women who received PST, those with high levels of cancer-specific distress were two times more likely to improve in BSE adherence than women low in cancer-specific distress. There was no effect of cancer-specific distress in the control condition. These results suggest that women with a family history of breast cancer who have high levels of distress may be most likely to benefit from behavioral coping skills intervention to promote adherence to breast cancer screening.

Adaptation, Psychological↗