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Biomedical subjects

M Stampfer

Publications and source records attributed to M Stampfer.

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

Menstrual factors in relation to breast cancer risk.

We evaluated menstrual factors in relation to breast cancer risk in a large, population-based, case-control study. Case women were ascertained through state-wide registries covering Wisconsin, Western Massachusetts, Maine, and New Hampshire; control women were randomly selected from driver's license and Medicare lists in each state. Information regarding menstrual characteristics was obtained through a telephone interview. The study population comprised 6888 breast cancer cases and 9529 control women. Because exogenous hormones influence menstrual cycle patterns, we repeated our analyses in a subgroup of women who had never used oral contraceptives or hormone replacement therapy. Our results indicate decreased breast cancer risk with menarcheal age of 15 years or more, relative to menarche at age 13; the relation was stronger among premenopausal [odds ratio (OR), 0.72; 95% confidence interval (CI), 0.57-0.91] as opposed to postmenopausal women (OR, 0.90; 95% CI, 0.80-1.03). Risk was slightly reduced among premenopausal women whose menstrual cycles did not become regular until at least 5 years after onset of menses, relative to those whose cycles became regular within 1 year (OR, 0.80; 95% CI, 0.63-1.02). There was no clear relation between breast cancer risk and irregular menstrual cycles, episodes of amenorrhea, or menstrual cycle length. Early menopause, whether natural or surgical, was associated with decreased breast cancer risk; surgical menopause before age 40 conferred the strongest protective effect (OR, 0.57; 95% CI, 0.47-0.71). We found no evidence of increased risk with late natural menopause (OR, 0.92; 95% CI, 0.80-1.06). Results in the subgroup of women who never used exogenous hormones were similar to those for the entire group.

Adult↗
PubMed1998

Glutathione S-transferase GSTM1 and GSTT1 polymorphisms and colorectal cancer risk: a prospective study.

Glutathione S-transferase (GST) M1 and T1 genes encode GST enzymes, and are polymorphic in humans. These enzymes catalyze conjugation with glutathione, which is an important step in the detoxification of certain carcinogens. Several case-control studies have found associations of the homozygous null deletions in GSTM1 and GSTT1 with increasing the risk of colorectal and lung cancer. We prospectively examined the associations of the GSTM1 and GSTT1 polymorphisms with colorectal cancer risk in a nested case-control study (212 cases of colorectal cancer and 221 controls) within the Physicians' Health Study. Among controls, the prevalence of the GSTM1 homozygous null genotype was 53% and for GSTT1 homozygous null genotype, 23%. We found no increase in the risk of colorectal cancer for either GSTM1 null [odds ratio (OR) = 1.0; 95% confidence interval (CI), 0.7-1.5] or GSTT1 null (OR = 0.8; 95% CI, 0.5-1.2) genotypes. No differences were seen by site of colon cancer (proximal versus distal) or by age (< or = 60 years versus > 60 years). Current cigarette smokers with GSTM1 null genotype were not at an increased risk of colon cancer (OR = 1.2; 95% CI, 0.3-4.2) compared with current smokers without the null genotype; for the GSTT1 null genotype this OR was 1.1 = 95% CI (0.3-4.7). This lack of association persisted when we examined pack-years of smoking and age at starting smoking. Our results do not support an association of GSTM1 or GSTT1 polymorphisms with colorectal cancer or an interaction with cigarette smoking.

Adult↗
PubMed1998

Debrisoquine hydroxylase (CYP2D6) and prostate cancer.

The p450 hepatic microsomal enzyme system metabolizes exogenous drugs and carcinogens. Debrisoquine hydroxylase (CYP2D6), one member of the p450 hemoproteins, has polymorphic expression leading to poor metabolism of debrisoquine and similar compounds in approximately 7% of Caucasians. The genetic locus for this enzyme has been characterized, and the mutations responsible for the slowed metabolism have been identified. Epidemiological studies of the CYP2D6 phenotype suggest an association between the normal or rapid metabolism phenotype and increased risk of lung and bladder cancer. Preliminary data have also suggested an association with prostate cancer (CaP). We used a PCR-based assay to investigate possible associations between the CYP2D6 B allele, the most common genetic mutation responsible for the poor metabolism phenotype, and CaP. Using genomic DNA isolated from peripheral blood, we genetically typed 571 men with CaP and 767 matched controls, all participants in the Physician's Health Study. Relative to men homozygous for the wild-type allele, heterozygotes for the B allele have an odds ratio of 1.19 (95% confidence interval, 0.94-1.51) for CaP, and men homozygous for the B allele have an odds ratio of 1.37 (95% confidence interval, 0.86-2.20). When analyzed as a trend over zero, one, or two copies of the B allele, there emerges a possible association between the B allele and an increased risk of CaP of borderline statistical significance (P = 0.07).

Adult↗
PubMed1997

[Planned 3-dimensional low-volume conformal irradiation of a local prostatic carcinoma].

AIM: Recent data have shown a significant reduction of acute side effects by means of a three-dimensional planned conformal radiotherapy of carcinoma of the prostate compared to treatment techniques used before. Theoretically, an optimized field coverage of the planning target volume should result in a reduction of treated bladder and rectum volumes. We studied the effects of individualized blocks on treatment volumes, planning target volumes, irradiated bladder and rectum volumes on basis of three-dimensional treatment planning by means of beam's-eye-view technique. PATIENTS AND METHOD: We compared dose-volume-histograms of 2 different planning models, a (fictitious) open 4-field-box-technique and a technique with conformal blocked fields designed from the beam's-eye-view display (prescribed dose 66 Gy, daily single fraction 2 Gy). Plans of 115 patients with localized prostate cancer treated from January 1994 to February 1996 were analyzed. RESULTS: Using individualized fields treatment volume (covered by the 90%-isodose) was reduced by 23% on the average in comparison to the planning model without blocks. The averaged difference of treated volume and planning target volume, as a grade of efficiency of conformation, was reduced by 38% (496 cm3 303 cm3) using individualized blocks. 23% of the treated bladder volume and 13% of the treated rectum volume had been saved on the average. Nevertheless, at least 11.5% of the bladder volume and 27.6% of the contoured rectum volume were treated with the prescribed dose (55 Gy = 100%). CONCLUSIONS: The comparison of dose-volume-histogram-data showed that especially high dose volumes of organs at risk had been saved by means of individualized blocks created from the beam's-eye-view. The blocks did not affect the dose distribution of the planning target volume adversely. Consequently the impact of these data on the extent of side effects and local tumor control has to be proven.

Aged↗
PubMed1997

Observational epidemiology is the preferred means of evaluating effects of behavioral and lifestyle modification.

In evaluating the health effects of behavioral change, randomized trials have the clear advantage of being able to provide unbiased and unconfounded estimates. However, in practice, many difficulties loom that limit the utility of trials. These include the inability to assess adverse behavior (except indirectly), the often unrealistic requirement for very prolonged adherence--perhaps for decades--to the randomized assignment, the requirement for huge numbers for precise estimates of effect (as opposed to simply a "significant result"), and the ethical problem of giving a placebo when an efficacious agent is available. We must be alert to feasible opportunities to test behavioral changes in clinical trials, but the many limitations mean that we will continue to rely on well-conducted, large-scale observational studies for most of our evidence on the effects of behavioral change.

Epidemiologic Studies↗
PubMed1997

Serum steroids in relation to prostate cancer risk in a case-control study (Greece).

Blood samples were collected from 52 incident cases of histologically confirmed prostate cancer and 52 age- and town of residence-matched healthy controls in Athens, Greece. Samples were analyzed blindly in Boston, Massachusetts (USA) for testosterone (T), estradiol (E2), sex hormone-binding globulin (SHBG), and dihydrotestosterone (DHT). The data were modeled using multiple logistic regression with adjustment for age, height, body mass index (wt/ht2), years of schooling, and mutually among hormones. DHT was associated inversely, significantly, and strongly with the risk of prostate cancer, whereas T was associated marginally positively, and E2 was associated nonsignificantly inversely with the disease. No association was observed in this study with respect to SHBG.

Aged↗
PubMed1997

Insulin-like growth factor 1 in relation to prostate cancer and benign prostatic hyperplasia.

Blood samples were collected from 52 incident cases of histologically confirmed prostate cancer, an equal number of cases of benign prostatic hyperplasia (BPH) and an equal number of apparently healthy control subjects. The three groups were matched for age and town of residence in the greater Athens area. Steroid hormones, sex hormone-binding globulin, and insulin-like growth factor 1 (IGF-1) were measured in duplicate by radioimmunoassay in a specialized US centre. Statistical analyses were performed using multiple logistical regression. The results for IGF-1 in relation to prostate cancer and BPH were adjusted for demographic and anthropometric factors, as well as for the other measured hormones. There was no relation between IGF-1 and BPH, but increased values of this hormone were associated with increased risk of prostate cancer; an increment of 60 ng ml(-1) corresponded to an odds ratio of 1.91 with a 95% confidence interval of 1.00-3.73. There was also some evidence for an interaction between high levels of testosterone and IGF-1 in relation to prostate cancer. This finding suggests that, in addition to testosterone, IGF-1 may increase the risk of prostate cancer in humans.

Aged↗
PubMed1996

Dietary fat and risk of coronary heart disease in men: cohort follow up study in the United States.

OBJECTIVE: To examine the association between fat intake and the incidence of coronary heart disease in men of middle age and older. DESIGN: Cohort questionnaire study of men followed up for six years from 1986. SETTING: The health professionals follow up study in the United States. SUBJECTS: 43 757 health professionals aged 40 to 75 years free of diagnosed cardiovascular disease or diabetes in 1986. MAIN OUTCOME MEASURE: Incidence of acute myocardial infarction or coronary death. RESULTS: During follow up 734 coronary events were documented, including 505 non-fatal myocardial infarctions and 229 deaths. After age and several coronary risk factors were controlled for significant positive associations were observed between intake of saturated fat and risk of coronary disease. For men in the top versus the lowest fifth of saturated fat intake (median = 14.8% v 5.7% of energy) the multivariate relative risk for myocardial infarction was 1.22 (95% confidence interval 0.96 to 1.56) and for fatal coronary heart disease was 2.21 (1.38 to 3.54). After adjustment for intake of fibre the risks were 0.96 (0.73 to 1.27) and 1.72 (1.01 to 2.90), respectively. Positive associations between intake of cholesterol and risk of coronary heart disease were similarly attenuated after adjustment for fibre intake. Intake of linolenic acid was inversely associated with risk of myocardial infarction; this association became significant only after adjustment for non-dietary risk factors and was strengthened after adjustment for total fat intake (relative risk 0.41 for a 1% increase in energy, P for trend < 0.01). CONCLUSIONS: These data do not support the strong association between intake of saturated fat and risk of coronary heart disease suggested by international comparisons. They are compatible, however, with the hypotheses that saturated fat and cholesterol intakes affect the risk of coronary heart disease as predicted by their effects on blood cholesterol concentration. They also support a specific preventive effect of linolenic acid intake.

Adult↗
PubMed1996

Lack of effect of long-term supplementation with beta carotene on the incidence of malignant neoplasms and cardiovascular disease.

BACKGROUND: Observational studies suggest that people who consume more fruits and vegetables containing beta carotene have somewhat lower risks of cancer and cardiovascular disease, and earlier basic research suggested plausible mechanisms. Because large randomized trials of long duration were necessary to test this hypothesis directly, we conducted a trial of beta carotene supplementation. METHODS: In a randomized, double-blind, placebo-controlled trial of beta carotene (50 mg on alternate days), we enrolled 22,071 male physicians, 40 to 84 years of age, in the United States; 11 percent were current smokers and 39 percent were former smokers at the beginning of the study in 1982. By December 31, 1995, the scheduled end of the study, fewer than 1 percent had been lost to follow-up, and compliance was 78 percent in the group that received beta carotene. RESULTS: Among 11,036 physicians randomly assigned to receive beta carotene and 11,035 assigned to receive placebo, there were virtually no early or late differences in the overall incidence of malignant neoplasms or cardiovascular disease, or in overall mortality. In the beta carotene group, 1273 men had any malignant neoplasm (except nonmelanoma skin cancer), as compared with 1293 in the placebo group (relative risk, 0.98; 95 percent confidence interval, 0.91 to 1.06). There were also no significant differences in the number of cases of lung cancer (82 in the beta carotene group vs. 88 in the placebo group); the number of deaths from cancer (386 vs. 380), deaths from any cause (979 vs. 968), or deaths from cardiovascular disease (338 vs. 313); the number of men with myocardial infarction (468 vs. 489); the number with stroke (367 vs. 382); or the number with any one of the previous three end points (967 vs. 972). Among current and former smokers, there were also no significant early or late differences in any of these end points. CONCLUSIONS: In this trial among healthy men, 12 years of supplementation with beta carotene produced neither benefit nor harm in terms of the incidence of malignant neoplasms, cardiovascular disease, or death from all causes.

Adult↗
PubMed1996

Dietary consumption and plasma concentrations of vitamin E in pregnancies complicated by preeclampsia.

OBJECTIVE: Vitamin E, a potent antioxidant, has been suggested to play a role in preventing preeclampsia. Our aim was to determine whether consumption and plasma levels of vitamin E are lower in the preeclamptic than in normal women. STUDY DESIGN: A case-control study design was used. We identified 48 women with preeclampsia (late-pregnancy hypertension, proteinuria, and hyperuricemia). Ninety normal women served as the control group. Vitamin E consumption was estimated by use of a previously validated dietary recall questionnaire administered by a single trained research nurse to 42 of the preeclamptic women and all 90 of the control women. Blood was drawn from all women and stored until assayed at -70 degrees C. Plasma vitamin E concentrations were determined by use of high-pressure liquid chromatography. RESULTS: The mean dietary vitamin E consumption was similar for both the preeclamptic and control group (11.74 +/- 9.39 vs 11.34 +/- 7.51 mg/24 hr, p = 0.73). When the analysis also included estimations of vitamin E supplements, the total consumption was found to be higher in those who had preeclampsia than in controls (37.20 +/- 20.54 vs 22.3 +/- 27.24 mg/24 hr, p = 0.003). The mean plasma vitamin E concentration was significantly higher in preeclamptic than in control patients (1.41 +/- 0.39 vs 1.15 +/- 0.32 mg/dl, p < 0.001). Among the preeclamptic patients, those with severe disease associated with HELLP (hemolysis, elevated liver enzymes, and low platelets) syndrome (n = 11) had the highest plasma vitamin E concentrations. CONCLUSIONS: We found no evidence that low vitamin E consumption is related to the development of preeclampsia. Higher plasma vitamin E concentrations in preeclamptic patients are speculated to represent a response to oxidative stress.

Adult↗
PubMed1990

Coffee, caffeine, and cardiovascular disease in men.

BACKGROUND: For many years, an association between coffee consumption and the risk of coronary heart disease has been suspected. Although based on small numbers of end points, a prospective study has suggested a particularly strong association between recent coffee drinking and the incidence of cardiovascular disease. METHODS: We examined prospectively the relation of coffee consumption with the risk of myocardial infarction, need for coronary-artery bypass grafting or angioplasty, and risk of stroke in a cohort of 45,589 U.S. men who were 40 to 75 years old in 1986 and who had no history of cardiovascular disease. RESULTS: During two years of follow-up observation, 221 participants had a nonfatal myocardial infarction or died of coronary heart disease, 136 underwent coronary-artery surgery or angioplasty, and 54 had a stroke. Total coffee consumption was not associated with an increased risk of coronary heart disease or stroke. The age-adjusted relative risk for all cardiovascular disease among participants who drank four or more cups of coffee per day was 1.04 (95 percent confidence intervals, 0.74 to 1.46). Increasing levels of consumption of caffeinated coffee were not associated with higher risks of cardiovascular disease. Higher consumption of decaffeinated coffee, however, was associated with a marginally significant increase in the risk of coronary heart disease (relative risk, 1.63; 95 percent confidence interval, 1.02 to 2.60). Finally, we observed no pattern of increased risk across the subgroups of participants with increasing intakes of caffeine from all sources. Adjustment for major cardiovascular-risk indicators, dietary intake of fats, and cholesterol intake did not materially alter these associations. CONCLUSIONS: These findings do not support the hypothesis that coffee or caffeine consumption increases the risk of coronary heart disease or stroke.

Adult↗