Biomedical subjects

Daniel O Stram

Publications and source records attributed to Daniel O Stram.

40 records · Page 3Linked to original sources

PubMed2002

Is residual confounding a reasonable explanation for the apparent protective effects of beta-carotene found in epidemiologic studies of lung cancer in smokers?

The results of three randomized trials of beta-carotene supplementation for the prevention of lung cancer among smokers are in contradiction to a large body of epidemiologic evidence for the reduction of risk of lung cancer among smokers with higher intake and/or higher serum levels of beta-carotene. Complicating this issue are widely noted negative associations between tobacco use and intake or serum levels of beta-carotene. Although observational studies attempt to control for reported smoking histories, the accuracy of self-reported smoking is uncertain; correlations as low as 0.5 between reported and true smoking exposure are not inconsistent with studies of biomarkers of cigarette exposure. The authors developed a simple statistical model for random errors in reported smoking (relative to true tobacco exposure) and assumed a modest (inverse) relation between true tobacco exposure and serum beta-carotene. Calculations from this model, combined with a model for lung cancer contemplated by Doll and Peto (J Epidemiol Community Health 1978;78:303-13), suggest that biases in assessment of smoking exposure between smokers with low versus high beta-carotene intake may plausibly explain much or all of the observed protective effect of high beta-carotene levels. Appropriate cohort studies of lung cancer in smokers, utilizing biomarkers of smoking, are needed and are presently ongoing.

Antioxidants↗

PubMed2002

Breast-feeding and neuroblastoma, USA and Canada.

OBJECTIVE: Researchers have suggested an inverse association between breast-feeding and risk of childhood cancer. We investigated the association between breast-feeding and neuroblastoma in a large case-control study in the United States and Canada. METHODS: Maternal reports of breast-feeding were compared among 393 children six months or older who had neuroblastoma and were identified through the Children's Cancer Group and the Pediatric Oncology Group and 376 age-matched controls identified by random-digit telephone dialing in a telephone interview case-control study. RESULTS: Children with neuroblastoma were less likely to have breast-fed than control children (odds ratio (OR) = 0.6; 95% confidence interval (CI) = 0.5-0.9). The association between breast-feeding and neuroblastoma increased with breast-feeding duration (0-3 months OR = 0.7, CI = 0.4-1.0; 13+ months OR = 0.5, CI = 0.3-0.9). CONCLUSION: Breast-feeding was inversely associated with neuroblastoma and should be encouraged among healthy mothers. Additional research on possible mechanisms of this association may be warranted.

Adolescent↗

PubMed2002

Breast cancer in a multiethnic cohort in Hawaii and Los Angeles: risk factor-adjusted incidence in Japanese equals and in Hawaiians exceeds that in whites.

Few data exist on the extent to which the differences in breast cancer risk between "racial-ethnic" groups in the United States (US) are "explained" by differences in their distribution of risk factors. We have determined this for African-American (AA), native Hawaiian (NH), Japanese-American (JA), Latina-US-born (L-US), Latina-non-US-born (L-NUS), and white (W) women using prospective incidence data on 88,712 postmenopausal women recruited in 1993-1996. We identified 1,757 incident breast cancer cases through 1999 among these women (1,116 cases after excluding women with a simple hysterectomy or missing risk factor data). Data were available on seven "known" risk factors: ages at menarche and first birth; parity; age at and type of menopause; weight; hormone replacement therapy use; and alcohol consumption. The relative risks (RRs) of breast cancer (with the RR in Ws set to 1.0) for the groups were as follows: W = 1.0; AA = 0.78; NH = 1.33; JA = 0.99; L-US = 0.77; and L-NUS = 0.60. After adjustment for the risk factors, the RRs were as follows: W = 1.0; AA = 0.98; NH = 1.65; JA = 1.11; L-US = 0.95; and L-NUSB = 0.84. The slightly greater risk of the JAs compared with the Ws is in sharp contrast to the very low breast cancer rates that were observed in "traditional" Japanese women and in early Japanese migrants. The adjusted RR of NHs is 65% greater than that of Ws, and that of migrant Latinas is 16% lower than that of Ws. Elucidating the causes of the high rates in NHs is now a major focus of our efforts.

Aged↗

PubMedDate not supplied

Designs for studies of personal exposure to air pollution and the impact of measurement error.

This article discusses the impact of measurement error on various designs for the study of the health effects on humans of exposure to air pollution. It discusses time-series studies in which total deaths (or other events) are related to day-to-day variations in air pollution level, and relates the power of these studies to the power of more complex studies in which geographical variation and data on individual exposures are included in time-series analysis, and in which individual outcomes are included as well. Much emphasis is on the recent analysis of Sheppard (this issue) as a source of information concerning variations in grouped and individual air pollution.

Air Pollutants↗