Auto-antibodies to p53 and the Subsequent Development of Colorectal Cancer in a United States Prospective Cohort Consortium

Auto-antibodies to tumor suppressor p53 are found in a subset of colorectal cancer (CRC) patients. A prospective cohort study in the US (Cancer Prevention Study II) has recently reported a statistically significant 1.8-fold increased odds for the development of CRC based on pre-diagnostic sero-positivity for p53; the magnitude of this association decreased with longer time-span between blood sampling and diagnosis. In the present study, we sought to examine this association in a large US CRC cohort consortium to evaluate the potential utility of p53 auto-antibodies as an early CRC detection biomarker. Methods: Antibody responses to p53 were measured in pre-diagnostic blood samples of 3,702 incident CRC cases (median [range] follow-up: 7.3 years [0–40 years]) and an equal number of controls, matched by age, race, and sex, from 9 US prospective cohorts. The association of sero-positivity to p53 with CRC risk, overall and by time between blood draw and diagnosis, was determined by conditional logistic regression. Results: Overall, 5% of controls and 7% of cases were sero-positive to p53, resulting in a statistically significant 33% increased CRC risk (OR: 1.33; 95% CI: 1.09, 1.61). The association was strongest for CRC diagnoses within 2 years after blood draw (OR: 2.73; 95% CI: 1.67, 4.45), with 15% sero-positive cases compared to 6% sero-positive controls. The number of sero-positive cases decreased with longer follow-up time (2–<5 years: 9%; 5–<10 years: 6%; ≥10 years: 3%) down to a proportion similar to that in controls resulting in the absence of an association of p53 sero-positivity with CRC risk after more than 5 years between blood draw and CRC diagnosis. Conclusion: In this large consortium of prospective cohorts, we found that pre-diagnostic sero-positivity to the tumor suppressor p53 was statistically significantly associated with a 2.7-fold increased risk of a subsequent CRC diagnosis within 2 years after blood draw, replicating the findings of the one previous cohort study examining this association. The findings suggest that while p53 sero-positivity may not be a useful predictor of long-term CRC risk, p53 auto-antibodies might be considered as part of a marker panel for early detection of this cancer.

No association between circulating concentrations of vitamin D and risk of lung cancer: an analysis in 20 prospective studies in the Lung Cancer Cohort Consortium (LC3)

Background

There is observational evidence suggesting that high vitamin D concentrations may protect against lung cancer. To investigate this hypothesis in detail, we measured circulating vitamin D concentrations in prediagnostic blood from 20 cohorts participating in the Lung Cancer Cohort Consortium (LC3).

Patients and methods

The study included 5313 lung cancer cases and 5313 controls. Blood samples for the cases were collected, on average, 5 years before lung cancer diagnosis. Controls were individually matched to the cases by cohort, sex, age, race/ethnicity, date of blood collection, and smoking status in five categories. Liquid chromatography coupled with tandem mass spectrometry was used to separately analyze 25-hydroxyvitamin D2 [25(OH)D2] and 25-hydroxyvitamin D3 [25(OH)D3] and their concentrations were combined to give an overall measure of 25(OH)D. We used conditional logistic regression to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for 25(OH)D as both continuous and categorical variables.

Results

Overall, no apparent association between 25(OH)D and risk of lung cancer was observed (multivariable adjusted OR for a doubling in concentration: 0.98, 95% CI: 0.91, 1.06). Similarly, we found no clear evidence of interaction by cohort, sex, age, smoking status, or histology.

Conclusion

This study did not support an association between vitamin D concentrations and lung cancer risk.

Systematic review with meta-analysis: the comparative effectiveness of aspirin vs. screening for colorectal cancer prevention

BACKGROUND

Both aspirin use and screening with flexible sigmoidoscopy or guaiac faecal occult blood testing (FOBT) may reduce mortality from colorectal cancer, but comparative effectiveness of these interventions is unknown.

AIM

To compare aspirin to guaiac FOBT screening with regard to incidence and mortality of colorectal cancer in a network meta-analysis.

METHODS

We searched Medline, EMBASE and the COCHRANE central register (CENTRAL) for relevant randomised trials identified until 31 October 2015. Randomised trials in average-risk populations that reported colorectal cancer mortality, colorectal cancer incidence, or both, with a minimum follow-up of 2 years, and more than 100 randomised individuals were included. Three investigators independently extracted data. We calculated relative risks [RR with 95% predictive intervals (PrIs)] for the comparison of the interventions by frequentist network meta-analyses.

RESULTS

The effect of aspirin on colorectal cancer mortality was similar to FOBT (RR 1.03; 95% PrI 0.76-1.39) and flexible sigmoidoscopy (RR 1.16; 95% PrI 0.84-1.60). Aspirin was more effective than FOBT (RR 0.36; 95% PrI 0.22-0.59) and flexible sigmoidoscopy (RR 0.37; 95% PrI 0.22-0.62) in preventing death from or cancer in the proximal colon. Aspirin was equally effective as screening in reducing colorectal cancer incidence, while flexible sigmoidoscopy was superior to FOBT (RR 0.84; 95% PrI 0.72-0.97).

CONCLUSIONS

Low-dose aspirin seems to be equally effective as flexible sigmoidoscopy or guaiac FOBT screening to reduce colorectal cancer incidence and mortality, and more effective for cancers in the proximal colon. A randomised comparative effectiveness trial of aspirin vs. screening is warranted.

Central adiposity, obesity during early adulthood, and pancreatic cancer mortality in a pooled analysis of cohort studies

BACKGROUND

Body mass index (BMI), a measure of obesity typically assessed in middle age or later, is known to be positively associated with pancreatic cancer. However, little evidence exists regarding the influence of central adiposity, a high BMI during early adulthood, and weight gain after early adulthood on pancreatic cancer risk.

DESIGN

We conducted a pooled analysis of individual-level data from 20 prospective cohort studies in the National Cancer Institute BMI and Mortality Cohort Consortium to examine the association of pancreatic cancer mortality with measures of central adiposity (e.g. waist circumference; n = 647 478; 1947 pancreatic cancer deaths), BMI during early adulthood (ages 18-21 years) and BMI change between early adulthood and cohort enrollment, mostly in middle age or later (n = 1 096 492; 3223 pancreatic cancer deaths). Multivariable hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox proportional hazards regression models.

RESULTS

Higher waist-to-hip ratio (HR = 1.09, 95% CI 1.02-1.17 per 0.1 increment) and waist circumference (HR = 1.07, 95% CI 1.00-1.14 per 10 cm) were associated with increased risk of pancreatic cancer mortality, even when adjusted for BMI at baseline. BMI during early adulthood was associated with increased pancreatic cancer mortality (HR = 1.18, 95% CI 1.11-1.25 per 5 kg/m(2)), with increased risk observed in both overweight and obese individuals (compared with BMI of 21.0 to <23 kg/m(2), HR = 1.36, 95% CI 1.20-1.55 for BMI 25.0 < 27.5 kg/m(2), HR = 1.48, 95% CI 1.20-1.84 for BMI 27.5 to <30 kg/m(2), HR = 1.43, 95% CI 1.11-1.85 for BMI ≥30 kg/m(2)). BMI gain after early adulthood, adjusted for early adult BMI, was less strongly associated with pancreatic cancer mortality (HR = 1.05, 95% CI 1.01-1.10 per 5 kg/m(2)).

CONCLUSIONS

Our results support an association between pancreatic cancer mortality and central obesity, independent of BMI, and also suggest that being overweight or obese during early adulthood may be important in influencing pancreatic cancer mortality risk later in life.

Reproductive factors, exogenous hormone use and risk of hepatocellular carcinoma among US women: results from the Liver Cancer Pooling Project

BACKGROUND

Hepatocellular carcinoma (HCC) occurs less commonly among women than men in almost all regions of the world. The disparity in risk is particularly notable prior to menopause suggesting that hormonal exposures during reproductive life may be protective. Exogenous oestrogenic exposures such as oral contraceptives (OCs), however, have been reported to increase risk, suggesting that estrogens may be hepatocarcinogenic. To examine the effects of reproductive factors and exogenous hormones on risk, we conducted a prospective analysis among a large group of US women.

METHODS

In the Liver Cancer Pooling Project, a consortium of US-based cohort studies, data from 799,500 women in 11 cohorts were pooled and harmonised. Cox proportional hazards regression models were used to generate hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations of reproductive factors and exogenous hormones with HCC (n=248).

RESULTS

Bilateral oophorectomy was associated with a significantly increased risk of HCC (HR=2.67, 95% CI=1.22-5.85), which did not appear to be related to a shorter duration of exposure to endogenous hormones or to menopausal hormone therapy use. There was no association between OC use and HCC (HR=1.12, 95% CI=0.82-1.55). Nor were there associations with parity, age at first birth, age at natural menopause, or duration of fertility.

CONCLUSIONS

The current study suggests that bilateral oophorectomy increases the risk of HCC but the explanation for the association is unclear. There was no association between OC use and HCC risk. Examination of endogenous hormone levels in relation to HCC may help to clarify the findings of the current study.

Association of body mass index in early adulthood and middle age with future site-specific cancer mortality: the Harvard Alumni Health Study

BACKGROUND

The association between adiposity in early adulthood and subsequent development of specific malignancies is unclear. Further, the potential for mediation by adiposity in middle age has not been well examined. In a rare study, we investigated the association of body mass index (BMI) in early adulthood with mortality from several site-specific cancers.

DESIGN

In the Harvard Alumni Health Study cohort, 19 593 males had a physical examination at the university between 1914 and 1952 (mean age: 18.4 years) and returned a questionnaire in 1962 or 1966 (mean age = 45.1 years). BMI was computed using weight (kg)/height(2) (m(2)) at both time points. Vital status follow up continued for a maximum of 82 years.

RESULTS

Positive early adulthood cancer mortality gradients by BMI were found for all malignancies combined (adjusted hazard ratio [HR] = 1.11; 95% confidence interval [CI]: 1.05-1.17 for a one standard deviation increase in early adulthood BMI), and for lung (HR = 1.24; 95% CI = 1.10-1.40) and skin (HR = 1.29; 95% CI = 0.96-1.75) cancers. There were also apparent associations for cancers of the oesophagus and urogenital sites. Mediation by BMI in middle age was found to be minimal.

CONCLUSION

Higher BMI in early adulthood appears to be a direct risk factor for selected malignancies several decades later.

Hemoglobin A1c, body mass index, and the risk of hypertension in women

BACKGROUND

Although basic research has implicated abnormal glucose metabolism in the pathogenesis of hypertension (HTN), epidemiologic studies are limited.

METHODS

We assessed whether baseline hemoglobin A(1c) (HbA(1c)) was prospectively associated with HTN in the Women's Health Study (WHS). We analyzed 19,858 women initially free of HTN, diabetes, and cardiovascular disease (CVD) with baseline blood samples. We considered quintiles and clinical cutpoints of HbA(1c) for the risk of HTN, defined as either a new physician diagnosis, the initiation of antihypertensive treatment, or systolic blood pressure (SBP) ≥140 or diastolic blood pressure (DBP) ≥90 mm Hg.

RESULTS

During a median follow-up of 11.6 years, 9,408 (47.5%) women developed HTN. In models adjusted for traditional cardiovascular risk factors, the hazard ratios (HRs) from the lowest (<4.8%, referent) to the highest (≥5.2%) quintile of HbA(1c) were 1.0 (referent), 0.99, 1.06, 1.08, and 1.21 (P, linear trend <0.0001). However, additional adjustment for body mass index (BMI) eliminated the relation (extreme quintile comparison HR 1.04; P, linear trend 0.10). For clinical cutpoints, a similar pattern emerged although a positive association between HbA(1c) and HTN remained in the highest category.

CONCLUSIONS

HbA(1c) in women without diabetes was associated with an increased risk of HTN in models controlling for the majority of traditional HTN and coronary risk factors, but this relation was no longer significant after adjustment for BMI. These findings underscore the need for additional studies to delineate the important inter-relationships between glycemia and adiposity with the risk of HTN in other study populations.

Smoking and the risk of incident hypertension in middle-aged and older men

BACKGROUND

Cigarette smoking is a known risk factor for cardiovascular disease (CVD), but its relationship to the development of hypertension is unclear. Previous epidemiological studies have shown inconsistent results, having demonstrated inverse and positive associations between cigarette smoking and the development of hypertension.

METHODS

We analyzed 13,529 male participants from the Physicians' Health Study free of baseline hypertension and CVD who provided information about smoking status. Smoking status was categorized as never, past, or current <20 cigarettes/day, or current > or =20 cigarettes/day. Incident hypertension was defined as either the initiation of antihypertensive treatment, self-reported systolic blood pressure (BP) > or =140 mm Hg, or diastolic BP > or =90 mm Hg.

RESULTS

Over a median follow-up of 14.5 years, 4,904 men developed hypertension. We modeled the risk of developing hypertension by baseline smoking status adjusting for known risk factors for hypertension or CVD. In a fully adjusted Cox proportional hazards model, we found that compared with never smokers, past smokers and current smokers had corresponding relative risks (RRs) of 1.08 and 1.15 of developing hypertension. The risk for smokers did not appear to differ based on number of cigarettes smoked daily. Further, the RR of hypertension was higher for men with normal vs. prehypertensive levels of systolic (SBP) or diastolic BP (DBP).

CONCLUSIONS

This prospective cohort data suggests that cigarette smoking may be a modest but important risk factor for the development of hypertension.

Physical activity and risk of Parkinson's disease: a prospective cohort study

BACKGROUND

Despite the fact that Parkinson's disease is the second most common neurodegenerative disease, little is known about risk factors for the disease. Laboratory experiments indicate that physical activity may have a neuroprotective effect; however, there are few data on whether physical activity is associated with decreased risk of Parkinson's disease.

AIM

To investigate the relationship between physical activity and Parkinson's disease in 10,714 men (mean age, 67.6 years) from the Harvard Alumni Health Study, who were diagnosed as free of self-reported Parkinson's disease in 1988.

METHODS

Physical activity was assessed in 1988 by asking about the daily number of blocks walked and stairs climbed, and participation in sports and recreational activities in the past week. Energy expenditure was then estimated and men were categorised into four groups: < 1000, 1000-1999, 2000-2999 or > or = 3000 kcal/week. In addition, physical activity data were available for three past time points: during college, 1962 or 1966, and 1977. Incident cases of Parkinson's disease occurring after 1988 (n = 101) were identified through a follow-up health questionnaire in 1993 and death certificates obtained until 1997.

RESULTS

In multivariate analyses, the relative risks (RR) for Parkinson's disease associated with < 1000, 1000-1999, 2000-2999 and > or = 3000 kcal/week of physical activity were 1 (referent), 1.15 (95% confidence interval (95% CI) 0.71 to 1.88), 0.92 (0.50 to 1.71) and 0.63 (0.36 to 1.12), respectively; p for trend was 0.12. When walking was examined separately, somewhat lower, but not significant, risks were observed for Parkinson's disease. The multivariate RRs (95% CI) for walking < 5, 5-10, 10-20 and > 20 km/week were 1 (referent), 0.67 (0.37 to 1.23), 0.81 (0.50 to 1.31) and 0.72 (0.39 to 1.34), respectively; p for trend was 0.26. Analyses that considered physical activity at other time points before 1988 did not show any significant associations.

CONCLUSIONS

These data do not strongly support the hypothesis that physical activity lowers the risk of Parkinson's disease. However, as the number of patients with Parkinson's disease in this study was not large, statistical power may have been limited and further large studies are needed to provide additional data.

Dairy products, calcium and prostate cancer risk

In a prospective study of 10 011 men with 815 prostate cancer cases, despite plausible biological mechanisms, neither increasing intake levels of dairy products nor calcium from dairy products (P trend; 0.23 and 0.64, respectively), or calcium supplements was associated with prostate cancer risk (relative risk, 1.05; 95% confidence interval, 0.84–1.31).

Blood pressure measures and risk of total, ischemic, and hemorrhagic stroke in men

OBJECTIVE

To evaluate which blood pressure measure is the best predictor of risk of total, ischemic, and hemorrhagic stroke.

METHODS

The authors used a prospective cohort study among 11,466 men followed for incident stroke during a median of 19.4 years in the Physicians' Health Study. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were self-reported. They calculated relative risks (RRs) and 95% CIs for total, ischemic, and hemorrhagic stroke using Cox proportional hazards models. Model fit was compared using the chi(2) test statistic from likelihood ratio tests.

RESULTS

During follow-up, 508 strokes occurred (411 ischemic, 89 hemorrhagic, and eight of unknown etiology). For each 10-mm Hg increase in SBP, the multivariable RRs were 1.31 (95% CI: 1.20 to 1.42) for total stroke, 1.28 (95% CI: 1.16 to 1.40) for ischemic stroke, and 1.38 (95% CI: 1.13 to 1.68) for hemorrhagic stroke. Although DBP, pulse pressure, and mean arterial pressure were all significant predictors of stroke risk, none was a significantly better predictor than SBP alone. Adding DBP did not significantly improve the model fit of SBP alone for any stroke type.

CONCLUSION

In this large cohort of initially healthy men, systolic blood pressure was a consistent and significant predictor of total, ischemic, and hemorrhagic stroke. Systolic blood pressure alone was the only measure necessary to predict risk of total stroke or its major subtypes.

Homocysteine and risk of developing hypertension in men

In cross-sectional studies, elevated homocysteine levels are associated with higher blood pressure, but it remains unclear whether plasma homocysteine is a risk factor for hypertension. In a prospective nested case-control study, participants who developed hypertension (n=396) had significantly higher levels of baseline plasma homocysteine (12.6 mol/l) than matched controls (11.8 mol/l, P=0.03); compared to those in the lowest quintile, those in the highest quintile had a crude relative risk (RR) of 1.56 (95% confidence interval (CI), 0.98-2.48; P for trend=0.10) and a multivariable RR of 1.63 (95% CI, 0.97-2.74; P for trend=0.13). Higher plasma homocysteine levels at baseline were associated with an increased but non-significant risk of incident hypertension that was minimally affected by multivariable adjustment.

Alcohol and cardiovascular health: recent findings

This review is focused on recent studies published since 1997 that have contributed toward our current thinking about the association between alcohol consumption and cardiovascular disease. Recent studies reinforce the consistent finding of a J-shaped inverse association between alcohol and cardiovascular disease morbidity and mortality, primarily due to an underlying association between alcohol and coronary heart disease (CHD). Despite the methodological difficulties of studying alcohol consumption, epidemiological studies are surprisingly consistent in showing that light to moderate alcohol intake has an inverse association with the risk of cardiovascular disease morbidity and mortality compared with those who do not drink at all. The depth and width of the J-shaped inverse association is largely dependent upon the underlying lowered risk of CHD. Alcohol likely reduces the risk of cardiovascular disease through increases in plasma high density lipoprotein-cholesterol (HDL-C) levels. Further support for the HDL-C hypothesis comes from the lack of a differential effect of alcohol by beverage type, suggesting that ethanol is responsible for the protective effect. While other mechanisms for a reduced risk of cardiovascular disease by alcohol have been suggested - including hemostatic markers and improvements and insulin sensitivity - evidence remains preliminary. The current recommendation set forth by the American Heart Association and other groups to limit alcohol intake to no more than 2 drinks per day for men and 1 drink per day for women appear justified but must be cautiously promoted. Although the association of alcohol and cardiovascular disease is likely to be causal, these recommendations must consider the complexity of the metabolic, physiological, and psychological effects of alcohol. In general, maximal benefits and safety appear to be at the level of approximately 1 drink per day. Limited data suggest that the level for optimal benefit and safety may be slightly lower for women. From a public policy standpoint, whether the benefits for cardiovascular disease persist at heavier drinking levels or are attenuated, may not be relevant since clear harm in terms of overall mortality would likely outweigh any benefits in the reduction of cardiovascular disease.

History of diabetes mellitus and risk of prostate cancer in physicians

Some studies have suggested that diabetes mellitus may decrease the risk of prostate cancer because of lower insulin levels. To further investigate the relation between diabetes and prostate cancer, a nested case-control study was conducted within the US Physicians' Health Study. Cases (n = 1,110) had been diagnosed with prostate cancer, confirmed on medical record review, during follow-up in 1982-1995. Controls (n = 1,110) were selected randomly from men free of prostate cancer and were matched on age and date of randomization. Information on personal history of diabetes and other diseases, lifestyle habits, and body weight/height was self-reported. Logistic regression analysis showed that the odds ratio for prostate cancer was 0.64 (95% confidence interval (CI): 0.43, 0.95) for men with diabetes, relative to those without the disease, after adjustment for potential confounders. Odds ratio estimates were 0.63 (95% CI: 0.35, 1.14), 0.77 (95% CI: 0.35, 1.72), 0.59 (95% CI: 0.21, 1.66), and 0.59 (95% CI: 0.27, 1.27) for diabetes diagnosed 1-5, 6-10, 11-15, and > or = 16 years prior to prostate cancer diagnosis (p for trend < 0.05). Adjusted odds ratios were 1.44 (95% CI: 0.34, 6.17) for stage A prostate cancer and 0.48 (95% CI: 0.28, 0.83) for stages B-D. Results suggest that history of diabetes may be associated with a decreased risk of prostate cancer, especially late-stage tumors.

Physical activity, body weight, and pancreatic cancer mortality

In a study of 32 687 subjects with data on physical activity and body mass index (BMI) collected serially over time, we examined associations with pancreatic cancer mortality (n=212). Despite plausible biologic mechanisms, neither physical activity (multivariate relative risks for increasing levels: 1.00, 0.98, 0.92, and 1.31, respectively) nor BMI (corresponding findings: 1.00, 0.84, 1.08, and 0.99, respectively) significantly predicted pancreatic cancer mortality.

Physical activity and all cause mortality in women: a review of the evidence

A computer assisted literature search was performed (Medline, 1966-2000) to examine the association of physical activity with all cause mortality in women. It was concluded that, by adhering to current guidelines for physical activity and expending about 4200 kJ of energy a week, women can postpone mortality. The magnitude of benefit experienced by women is similar to that seen in men.

Alcohol consumption and risk of prostate cancer: The Harvard Alumni Health Study

BACKGROUND

Although many studies suggest that consumption of alcohol increases the risk of several site-specific cancers, the evidence remains unclear for prostate cancer. Few data exist on beverage-specific associations as well as lifetime patterns of alcohol consumption and prostate cancer risk.

METHODS

We prospectively followed 7612 Harvard alumni (mean age 66.6 years) from 1988 through 1993, during which 366 cases of incident prostate cancer occurred. Self-reported alcohol consumption was assessed at baseline from wine, beer, and liquor intake. Previous assessments during college and in 1977 were also available.

RESULTS

Overall, the mean total alcohol consumption in 1988 was 123.1 g/week, of which 28.6% was from wine, 15.8% from beer, and 55.6% from liquor. Compared to men reporting almost never drinking alcohol in 1988, the multivariate relative risks (95% CI) for 1 drink/month to < 3 drinks/week, 3 drinks/week to < 1 drink/ day, 1 to < 3 drinks/day, and > or = 3 drinks/day were 1.33 (0.88-2.01), 1.65 (1.12-2.44), 1.85 (1.29-2.64), and 1.33 (0.86-2.05), respectively. Wine or beer consumption was unassociated with prostate cancer; however, moderate liquor consumption was associated with a significant 61-67% increased risk of prostate cancer (P, non-linear trend < 0.001). Men initiating alcohol consumption between 1977 and 1988 had a twofold increased risk of prostate cancer compared to men with almost no alcohol consumption at both times.

CONCLUSIONS

In contrast to the majority of previous studies, we found a positive association between moderate alcohol consumption and the risk of prostate cancer. Liquor, but not wine or beer, consumption was positively associated with prostate cancer.

Maternal and paternal history of myocardial infarction and risk of cardiovascular disease in men and women

BACKGROUND

Few studies have examined the effects of paternal and maternal history of myocardial infarction (MI), including age at MI, on cardiovascular disease (CVD) risk, particularly among women.

METHODS AND RESULTS

We prospectively studied 22 071 men from the Physicians' Health Study and 39 876 women from the Women's Health Study with data on parental history and age at MI. Among men, 2654 CVD cases developed over 13.0 years; among women, 563 CVD cases occurred over 6.2 years. Compared with men with no parental history, only maternal, only paternal, and both maternal and paternal history of MI conferred relative risks (RRs) of CVD of 1.71, 1.40, and 1.85; among women, the respective RRs were 1.46, 1.15, and 2.05. For men, maternal age at MI of <50, 50 to 59, 60 to 69, 70 to 79, and >/=80 years had RRs of 1.00, 1.88, 1.88, 1.67, and 1.17; for women, the RRs for maternal age at MI of <50, 50 to 59, and >/=60 years were 2.57, 1.33, and 1.52. Paternal age at MI of <50, 50 to 59, 60 to 69, 70 to 79, and >/=80 years in men had RRs of 2.19, 1.64, 1.42, 1.16, and 0.92; in women, for paternal age at MI of <50, 50 to 59, and >/=60 years, the RRs were 1.63, 1.33, and 1.13.

CONCLUSIONS

An early history of parental MI (<60 years) conferred a greater risk of CVD than did MI at older ages. However, an increased risk of CVD remained for maternal age at MI of 70 to 79 years in men and >/=60 years in women, which suggests that any maternal history of MI may be important.

A prospective cohort study of physical activity and body size in relation to prostate cancer risk (United States)

OBJECTIVES

To examine the associations of physical activity and body size with risk of prostate cancer.

METHODS

At baseline in 1988, 8922 men (mean age 67 years) completed a health questionnaire which included information on physical activity, body weight, and waist girth. In a subgroup (74% of men), physical activity data also had been provided in 1962 or 1966 and again in 1977. Additionally, body weight measured at age 18 was available for 92% of men. During follow-up from 1988 through 1993, 439 men developed prostate cancer.

RESULTS

In multivariate analyses that accounted for potential confounders, the RRs (95% CI) for < 4200, 4200-8399, 8400-12,599, and > or = 12,600 kJ/week of physical activity at baseline were 1.00 (referent), 1.13 (0.84-1.52), 0.96 (0.68-1.35), and 1.04 (0.79-1.38), respectively. For body mass indexes (BMI) of < 22.5, 22.5-24.9, 25.0-27.4, and > or = 27.5 kg/m2 at baseline, corresponding results were 1.00 (referent), 1.27 (0.94-1.71), 1.26 (0.92-1.72), and 1.02 (0.68-1.53), respectively. For waist girths of < or = 86.4, 86.5-91.4, 91.5-96.5, and > 96.5 cm, they were 1.00 (referent), 1.30 (0.96-1.76), 1.31 (0.96-1.80), and 1.19 (0.85-1.65), respectively. Combining physical activity measures from the past, or examining vigorous activities only, did not yield any significant associations. BMI at age 18 also was not related to risk.

CONCLUSION

These findings do not support a role of physical activity or body weight in prostate cancer etiology.

Systolic and diastolic blood pressure, pulse pressure, and mean arterial pressure as predictors of cardiovascular disease risk in Men

We compared systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure (PP), and mean arterial pressure (MAP) in predicting the risk of cardiovascular disease (CVD), stratifying results at age 60 years, when DBP decreases while SBP continues to increase. We prospectively followed 11 150 male physicians with no history of CVD or antihypertensive treatment through the 2-year questionnaire, after which follow-up began. Reported blood pressure was averaged from both the baseline and 2-year questionnaires. During a median follow-up of 10.8 years, there were 905 cases of incident CVD. For men aged <60 years (n=8743), those in the highest versus lowest quartiles of average SBP (>/=130 versus <116 mm Hg), DBP (>/=81 versus <73 mm Hg), and MAP (>/=97 versus <88 mm Hg) had relative risks (RRs) of CVD of 2.16, 2.23, and 2.52, respectively. Models with average MAP and PP did not add information compared with models with MAP alone (P>0.05). For men aged >/=60 years (n=2407), those in the highest versus lowest quartiles of average SBP (>/=135 versus <120 mm Hg), PP (>/=55 versus <44 mm Hg), and MAP (>/=99 versus <91 mm Hg) had RRs of CVD of 1.69, 1.83, and 1.43, respectively. The addition of other blood pressure measures did not add information compared with average SBP or PP alone (all P>0.05). These data suggest that average SBP, DBP, and MAP strongly predict CVD among younger men, whereas either average SBP or PP predicts CVD among older men. More research should distinguish whether MAP, highly correlated with SBP and DBP, better predicts CVD.

Seven-year changes in alcohol consumption and subsequent risk of cardiovascular disease in men

BACKGROUND

Few studies have examined whether changes in alcohol consumption influence future cardiovascular risk.

OBJECTIVE

To examine whether 7-year changes in alcohol consumption are associated with the subsequent risk of cardiovascular disease (CVD).

METHODS

We prospectively followed up 18,455 men aged 40 to 84 years from the Physicians' Health Study with no history of CVD or cancer. Alcohol consumption was reported on the baseline and the 7-year questionnaires; follow-up for this analysis began after the 7-year questionnaire (median follow-up, 5.8 years). There were 1091 CVD cases, including myocardial infarction, angina pectoris, revascularization, stroke, and CVD-related death.

RESULTS

Among men initially consuming 1 drink per week or less (n=7360), those with moderate increases (>1 to <6 drinks per week) in alcohol consumption had a borderline significant (P=.05) 29% reduced risk of CVD compared with men with no changes (-1 to 1 drink per week). Among men initially consuming greater than 1 to 6 drinks per week (n=6612), those with moderate increases had a nonsignificant (P=.32) 15% decrease in CVD risk compared with men with no changes. Finally, among men initially consuming 1 drink per day or more (n=4483), those who increased intake had a 63% increased risk of CVD compared with men with no changes.

CONCLUSIONS

These prospective data suggest that, among men with initially low alcohol consumption (</=1 drink per week), a subsequent moderate increase in alcohol consumption may lower their CVD risk. The possible reduction in CVD risk from increasing alcohol intake did not extend to men initially consuming greater than 1 drink per week. Given the potential risks and benefits associated with alcohol consumption, physician counseling of patients must be individualized in the context of the primary prevention of CVD.

Physical activity and coronary heart disease in men: The Harvard Alumni Health Study

BACKGROUND

The quantity and intensity of physical activity required for the primary prevention of coronary heart disease (CHD) remain unclear. Therefore, we examined the association of the quantity and intensity of physical activity with CHD risk and the impact of other coronary risk factors.

METHODS AND RESULTS

We followed 12 516 middle-aged and older men (mean age 57.7 years, range 39 to 88 years) from 1977 through 1993. Physical activity was assessed at baseline in kilojoules per week (4.2 kJ=1 kcal) from blocks walked, flights climbed, and participation in sports or recreational activities. During follow-up, 2,135 cases of incident CHD, including myocardial infarction, angina pectoris, revascularization, and coronary death, occurred. Compared with men expending <2,100 kJ/wk, men expending 2,100 to 4,199, 4,200 to 8,399, 8,400 to 12,599, and >/=12,600 kJ/wk had multivariate relative risks of 0.90, 0.81, 0.80, and 0.81, respectively (P: for trend=0.003). When we considered the independent effects of specific physical activity components, only total sports or recreational activities (P: for trend=0.042) and vigorous activities (P: for trend=0.02) were inversely associated with the risk of CHD. These associations did not differ within subgroups of men defined by coronary risk factors. Finally, among men with multiple coronary risk factors, those expending >/=4,200 kJ/wk had reduced CHD risk compared with men expending <4,200 kJ/wk.

CONCLUSIONS

Total physical activity and vigorous activities showed the strongest reductions in CHD risk. Moderate and light activities, which may be less precisely measured, showed nonsignificant inverse associations. The association between physical activity and a reduced risk of CHD also extends to men with multiple coronary risk factors.

Physical activity and coronary heart disease risk in men: does the duration of exercise episodes predict risk?

BACKGROUND

Physical activity is associated with a decreased risk of coronary heart disease (CHD). However, it is unclear whether the duration of exercise episodes is important: Are accumulated shorter sessions as predictive of decreased risk as longer sessions if the same amount of energy is expended?

METHODS AND RESULTS

In the Harvard Alumni Health Study, we prospectively followed 7307 Harvard University alumni (mean age 66.1 years) from 1988 through 1993. At baseline, men reported their walking, stair climbing, and participation in sports or recreational activities. For each of the latter activities, they also reported the frequency and average duration per episode. During follow-up, 482 men developed CHD. In age-adjusted analysis, a longer duration of exercise episodes predicted lower CHD risk (P: trend=0.04). However, after total energy expended on physical activity and potential confounders was accounted for, duration no longer had an independent effect on CHD risk (P: trend=0.25); that is, longer sessions of exercise did not have a different effect on risk compared with shorter sessions, as long as the total energy expended was similar. In contrast, higher levels of total energy expenditure significantly predicted decreased CHD risk in both age-adjusted (P: trend=0.009) and multivariate (P: trend=0.046) analyses.

CONCLUSIONS

These data clearly indicate that physical activity is associated with decreased CHD risk. Furthermore, they lend some support to recent recommendations that allow for the accumulation of shorter sessions of physical activity, as opposed to requiring 1 longer, continuous session of exercise. This may provide some impetus for those sedentary to become more active.

Two-year changes in blood pressure and subsequent risk of cardiovascular disease in men

BACKGROUND-It is unclear whether, given a current blood pressure level, the previous 2-year change in blood pressure adds important predictive information for cardiovascular disease (CVD). METHODS AND RESULTS-We conducted a prospective cohort study of 11 150 middle-aged and older men reporting blood pressure in the Physicians' Health Study. These men had no history of CVD or antihypertensive medication use through the time of the 2-year follow-up questionnaire; after this time, follow-up for the current study began. A total of 905 incident cases of CVD (705 cases of coronary heart disease and 200 cases of stroke) occurred during a median follow-up of 10.8 years. After controlling for current blood pressure and other coronary risk factors, we found that previous 2-year changes in systolic blood pressure were not associated with the risk of CVD. A similar lack of association was found for individual end points of coronary heart disease and stroke. However, previous 2-year changes in diastolic blood pressure (DBP) may be inversely associated with the risk of CVD (linear trend, P=0.049) independent of coronary risk factors and current DBP. In subgroup analyses, previous 2-year blood pressure changes only added information in leaner men (body mass index <24.39 kg/m(2)). CONCLUSIONS-In this normotensive population of men, the prior 2-year change in DBP, but not systolic blood pressure, may add information to current levels in relation to the risk of CVD. Clinicians may need to consider the previous pattern of DBP change when considering the risk associated with the current DBP level. These data require confirmation in other studies in which blood pressure is measured.

Comparison of National Death Index and World Wide Web death searches

The authors used the National Death Index and a World Wide Web Internet site that searches the Social Security Administration master files of deaths to determine the mortality status of 1,000 US subjects from the College Alumni Health Study. Subjects were classified as definitely dead, possibly dead, or presumed alive. Of 246 definite deaths pinpointed by the National Death Index, the World Wide Web identified 94.7% of them. Of 438 men presumed alive according to the National Death Index, the World Wide Web identified 97.5% of them. However, the World Wide Web was not useful for identifying deaths of women. This study demonstrated that the World Wide Web may provide an alternative, inexpensive method of determining the mortality status of subjects in relatively small epidemiologic studies.

Light-to-moderate alcohol consumption and mortality in the Physicians' Health Study enrollment cohort

OBJECTIVES

This study examined the relationship between light-to-moderate alcohol consumption and cause-specific mortality.

BACKGROUND

Previous studies suggest a J-shaped relation between alcohol and total mortality in men. A decrease in cardiovascular disease (CVD) mortality without a significant increase in other causes of mortality may explain the overall risk reduction at light-to-moderate levels.

METHODS

We conducted a prospective cohort study of 89,299 U.S. men from the Physicians' Health Study enrollment cohort who were 40 to 84 years old in 1982 and free of known myocardial infarction, stroke, cancer or liver disease at baseline. Usual alcohol consumption was estimated by a limited food frequency questionnaire.

RESULTS

There were 3,216 deaths over 5.5 years of follow-up. We observed a U-shaped relationship between alcohol consumption and total mortality. Compared with rarely/never drinkers, consumers of 1, 2 to 4 and 5 to 6 drinks per week and 1 drink per day had significant reductions in risk of death (multivariate relative risks [RRs] of 0.74, 0.77, 0.78 and 0.82, respectively) with no overall benefit or harm detected at the > or =2 drinks per day level (RR = 0.95; 95% confidence interval (CI), 0.79 to 1.14). The relationship with CVD mortality was inverse or L-shaped with apparent risk reductions even in the highest category of > or =2 drinks per day (RR = 0.76; 95% CI, 0.57 to 1.01). We found no clear harm or benefit for total or common site-specific cancers. For remaining other cancers, there was a nonsignificant 28% increased risk for those consuming > or =2 drinks per day.

CONCLUSIONS

These data support a U-shaped relation between alcohol and total mortality among light-to-moderate drinking men. The U-shaped curve may reflect an inverse association for CVD mortality, no association for common site-specific cancers and a possible positive association for less common cancers.

Clinical utility of lipid and lipoprotein levels during hospitalization for acute myocardial infarction

The management of dyslipidemia after myocardial infarction (MI) is an important aspect of post-myocardial infarction care. However, acute changes in the lipid profile immediately following myocardial infarction have resulted in uncertainty regarding the clinical utility of lipid levels assessed during hospitalization for MI. We studied the effect of the timing of plasma lipid assessment among 294 patients who presented with MI to determine whether the differences between the serum lipid values in-hospital when compared with post-discharge values (generally 2-3 months after MI) would have a substantial impact on the decision to initiate lipid-lowering therapy. We found that the mean total and LDL cholesterol levels were significantly lower in-hospital when compared with generally 2-3 months later. However, patients whose lipids were measured within 48 h of presentation did not have significantly different values compared with generally 2-3 months post-discharge. Moreover, despite slightly lower in-hospital levels, 83.7% of patients were above the National Cholesterol Education Program target LDL for secondary prevention and 57.6% met the criteria for drug therapy based on in-hospital assessment. Total and LDL cholesterol levels fall modestly after an acute MI; however, from a clinical perspective, in-hospital levels can be used to guide decisions regarding lipid-lowering therapy which can begin in the immediate post-MI setting. In-hospital levels approximate post-MI levels, particularly if drawn within 48 h of presentation. All patients with acute myocardial infarction should have complete lipid profiles measured prior to discharge.

Sense of exhaustion and coronary heart disease among college alumni

Vital exhaustion, defined as a combination of fatigue, lack of energy, feelings of hopelessness, loss of libido, and increased irritability, has been proposed as a risk indicator for the development of coronary heart disease (CHD). It is unclear if the association between vital exhaustion and CHD is independent of sleep behavior, depression, and physical activity. We ascertained sense of exhaustion among 5,053 male college alumni who were free of cardiovascular disease, cancer, and chronic obstructive pulmonary disease by asking, "How often do you experience sense of exhaustion (except after exercise)?" on a health survey in 1980. Eight hundred fifteen men died during 12 years of follow-up, 25% due to CHD. After adjustment for age, body mass index, smoking status, and history of physician-diagnosed diabetes and hypertension, frequent sense of exhaustion was associated with a twofold increase in CHD mortality (rate ratio 2.07; 95% confidence interval 1.08 to 3.96). After additional adjustment for insomnia, sleep duration, use of sleeping pills and tranquilizers, physical activity, history of physician-diagnosed depression, and alcohol intake, the rate ratio was not appreciably altered; however, the association now was of borderline significance (rate ratio 2.06; 95% confidence interval: 0.98 to 4.36) because there were only 10 deaths from CHD among men who were frequently exhausted. In a prospective observational study, frequent sense of exhaustion appeared to be independently associated with increased risk of CHD mortality in men.

Relation between systemic hypertension and blood lipids on the risk of myocardial infarction

We sought to evaluate the potential interactions between systemic hypertension and blood lipids on the risk of myocardial infarction (MI). Recent evidence suggests that hypertension may interact with other risk factors such as dyslipidemia in the development of coronary heart disease. However, the precise nature of that interrelation remains unclear. We selected 340 cases of first MI and an equal number of age-, sex-, and community-matched controls. Data were collected on a large number of coronary risk factors, and fasting blood samples were obtained. Logistic regression was used to calculate the odds ratio (OR) of nonfatal MI. The age- and sex-adjusted OR of MI was 1.61 (95% confidence interval [CI] 1.15 to 2.25) among treated hypertensives compared with nonhypertensives. Further adjustment for coronary risk factors did not materially alter the results (OR 1.67, 95% CI 1.16 to 2.41). To explore the interrelations among hypertension, lipids, and risk of MI, each lipoprotein parameter was individually added to the risk factor-adjusted multivariate model. The apparent risk associated with hypertension was substantially attenuated by the addition of either high-density lipoprotein cholesterol (OR 1.25, 95% CI 0.82 to 1.90) or triglycerides (OR 1.37, 95% CI 0.91 to 2.05). No significant interactions were found between hypertension and any lipoprotein parameter. These data indicate that the risk of MI associated with treated hypertension may have a lipid mechanism involving high-density lipoprotein cholesterol and/or triglycerides.

Physical activity and cardiovascular disease risk in middle-aged and older women

The authors investigated the relation between physical activity and cardiovascular disease (CVD) in women by following 1,564 University of Pennsylvania alumnae (mean age, 45.5 years), initially free of CVD, from 1962 until 1993. Energy expenditure was estimated from the daily number of flights of stairs climbed and blocks walked as well as the sports played and was categorized into approximate thirds (<500, 500-999, > or = 1,000 kcal/week). During 35,021 person-years, 181 CVD cases were identified. After adjustment for coronary risk factors, the relative risks of CVD were 0.99 (95% confidence interval (CI): 0.69, 1.41) and 0.88 (95% CI: 0.62, 1.25) for women who expended 500-999 and > or = 1,000, respectively, compared with <500 kcal/week (p for trend = 0.45). Only walking was found to be inversely related to CVD risk (p for trend = 0.054). Compared with women who walked <4 blocks/day, the relative risks of CVD were 0.84 (95% CI: 0.59, 1.19) and 0.67 (95% CI: 0.45, 1.01) for women who walked 4-9 and > or = 10 blocks/day, respectively. Finally, an interaction (p = 0.023) between body mass index and physical activity on CVD risk was observed, with an inverse association only for leaner (<23 kg/m2) women. These data showed no overall association of physical activity with CVD risk in women. However, walking > or = 10 blocks/day (approximately 6 miles (9.7 km)/week) was associated with a 33% decreased risk. One explanation for this finding may be that walking was reported more precisely than other kinds of activities.

Physical activity and risk of lung cancer

BACKGROUND

Physical activity has been proposed to decrease lung cancer risk; however, few data are available. Further, no studies have examined specific kinds and intensities of activities.

METHODS

We conducted a prospective cohort study among 13 905 male Harvard University alumni (mean age, 58.3 years), free of cancer. Men reported their walking, stair climbing and participation in sports or recreation on baseline questionnaires in 1977, and the occurrence of lung cancer on follow-up questionnaires in 1988 and 1993. Death certificates were obtained for decedents through 1992 to determine lung cancers not previously reported.

RESULTS

During follow-up, 245 men developed lung cancer. Adjusting for age, cigarette smoking, and body mass index, the relative risks of lung cancer associated with <4200, 4200-8399, 8400-12 599 and > or =12 600 kJ/week of estimated energy expenditure at baseline were 1.00 (referent), 0.87 (95% CI: 0.64-1.18), 0.76 (95% CI: 0.52-1.11), and 0.61 (95% CI: 0.41-0.89), respectively; P trend = 0.0008. Similar trends were observed among non-smokers or former smokers in 1977 (82.7% of men) as well as among those who smoked >20 cigarettes a day in 1977 (8.0%), although the findings in the latter group were not statistically significant, possibly due to the small number. Walking, climbing stairs and participating in activities of at least moderate intensity (> or =4.5 MET, or multiples of resting metabolic rate) were each inversely associated with lung cancer risk, independent of the other activity components. However, light intensity activities (<4.5 MET) did not predict lung cancer risk.

CONCLUSIONS

These data indicate that physical activity may be associated with lower risk of lung cancer among men. An energy expenditure of 12 600 kJ/week, achievable by perhaps 6-8 hours of at least moderate intensity physical activity, may significantly lower risk. Further studies are required to confirm these observations.

Alcohol intake and cardiovascular morbidity and mortality

Recent studies reinforce the consistent finding of a J-shaped inverse association between alcohol and cardiovascular disease morbidity and mortality, primarily as a result of the underlying association between alcohol and coronary heart disease. The most plausible mechanism behind this effect is through increases in high-density lipoprotein cholesterol. All types of alcoholic beverage reduce the risk of cardiovascular disease, suggesting that ethanol is responsible for the protective effect.

Coffee and tea intake and the risk of myocardial infarction

The authors investigated the association of caffeinated coffee, decaffeinated coffee, and tea with myocardial infarction in a study of 340 cases and age-, sex-, and community-matched controls. The odds ratio for drinking > or = 4 cups/day of caffeinated coffee versus drinking < or = 1 cup/week was 0.84 (95% confidence interval (CI) 0.49-1.42) after adjustment for coronary risk factors (1 cup = 237 ml). The odds ratio for drinking > 1 cup/day of decaffeinated coffee versus nondrinkers was 1.25 (95% CI 0.76-2.04). For tea, the odds ratio for drinking > or = 1 cup/day versus nondrinkers was 0.56 (95% CI 0.35-0.90). In these data, only tea was associated with a lower risk of myocardial infarction.

Type of alcoholic beverage and risk of myocardial infarction

We examined the relation of alcoholic beverage type and risk of myocardial infarction (MI) in a case-control study among 340 cases of MI and an equal number of age-, sex-, and community-matched controls. Alcohol consumption was estimated using a food frequency questionnaire, with alcohol drinkers defined as those consuming > or = 1/2 drink/day on average of any alcoholic beverage. Beer, wine, and liquor drinkers had at least half of their consumption from 1 beverage type. Fasting venous blood samples were obtained and analyzed for lipid profiles. Compared with nondrinkers, after adjustment for age and sex, reductions in risk of MI were similar for regular drinkers of any type of alcoholic beverage (relative risk [RR] 0.54; 95% confidence interval [CI] 0.37 to 0.79; p = 0.001), beer (RR 0.55; 95% CI 0.31 to 0.97; p <0.05), wine (RR 0.48; 95% CI 0.27 to 0.87; p <0.05), and liquor (RR 0.59; 95% CI 0.38 to 0.91; p <0.05) drinkers. Comparable benefits remained apparent even after multivariate adjustment for a wide range of nonlipid coronary risk factors. High-density lipoprotein (HDL) levels were significantly higher in all 4 beverage categories when compared with levels in nondrinkers, and as expected, adjustment for total HDL, a major direct effect of alcohol, substantially attenuated the protective effect in all 4 beverage categories. Relative risks were 0.94 for any beverage, 1.09 for beer, 0.97 for wine, and 0.83 for liquor after further adjustment. This strongly suggests that the protective effect of each beverage type is, in large part, mediated by increased HDL. These data indicate that regular consumption of small to moderate amounts of alcoholic beverages, regardless of the type, reduces the risk of MI, and further suggest that there is benefit, in large part, from increases in HDL levels.

Depression and the risk of coronary heart disease in the Normative Aging Study

Increasing evidence supports an association between symptomatic depression and the risk of coronary heart disease (CHD), although no single study has compared multiple depression scales. We hypothesized that higher levels of symptomatic depression assessed from different depression scales were associated with the risk of CHD. We examined this relation in the Normative Aging Study, a prospective cohort of older men. A total of 1,305 men free of diagnosed CHD in 1986 completed the revised Minnesota Multiphasic Personality Inventory (MMPI-2). We categorized scores for the MMPI-2 D, MMPI-2 DEP, and Symptom Checklist-90 (SCL-90) depression scales. During an average 7.0 years of follow-up, 110 cases of incident CHD occurred, including 30 cases of nonfatal myocardial infarction, 20 cases of fatal CHD, and 60 cases of angina pectoris. Compared with men reporting the lowest level of depression, men in the highest level of depression had multivariate-adjusted relative risks of incident CHD (total CHD and angina) of 1.46 (95% confidence interval 0.83 to 2.57), 2.07 (95% confidence interval 1.13 to 3.81), and 1.73 (95% confidence interval 0.97 to 3.10) for the MMPI-2 D, MMPI-2 DEP, and SCL-90 scales, respectively. Similar RRs were obtained for each CHD subtype according to each depression scale. We found strong dose-response relations between level of depression measured by the MMPI-2 DEP scale and incidence of both angina pectoris (p value for trend, 0.039) and CHD (p value for trend, 0.016). Among older men, symptomatic depression measured by any of 3 depression scales may be positively associated with the risk of CHD.

Physical activity and breast cancer risk in the College Alumni Health Study (United States)

OBJECTIVES

It is unclear whether physical activity is associated with a reduced risk of breast cancer. Some studies also suggest different effects between pre- and postmenopausal women, and lean and heavy women.

METHODS

We followed 1,566 University of Pennsylvania alumnae (mean age, 45.5 years), initially free of breast cancer, from 1962 until 1993. Physical activity at baseline was assessed by asking women about stairs climbed, blocks walked, and sports played. We estimated energy expenditure and categorized women into approximate thirds (< 500, 500-999, 1,000+ kcal/wk). We identified 109 breast cancer cases during 35,365 person-years from follow-up questionnaires or from death certificates.

RESULTS

After adjustment for age and body mass index (BMI) (kg/m2), the relative risk (RR) of breast cancer was 0.92 (95 percent confidence interval [CI] = 0.58-1.45) among women expending 500-999 kcal/wk and 0.73 (CI = 0.46-1.14) for those expending 1,000+ kcal/wk, compared with women expending < 500 kcal/wk (P trend = 0.17). This association was modified by menopausal status, but not BMI. For postmenopausal women, corresponding RRs were 0.95 (CI = 0.58-1.57) and 0.49 (CI = 0.28-0.86), respectively (P trend = 0.015). Increased physical activity in premenopausal women was not significantly associated with decreased risk of breast cancer.

CONCLUSIONS

These data support an inverse association between physical activity and breast cancer among postmenopausal women.

Cigarette advertising on taxicabs in Boston, Massachusetts (USA)

OBJECTIVE

To examine the frequency of tobacco advertisements on taxicabs within Boston, Massachusetts (USA).

DESIGN

At seven locations throughout Boston, an observer counted all taxicabs over 30-minute periods in December 1995.

MAIN OUTCOME MEASURES

Confirmed sightings of taxicabs with cigarette advertisements were recorded with information collected on the cigarette brand and taxicab company.

RESULTS

A total of 314 taxicabs were observed over 210 minutes of observation time, including 127 (40.4%) with cigarette advertisements. Taxicabs with cigarette advertisements were seen once every 1.65 minutes on average, with Marlboro as the most frequently advertised brand (69 of 127 advertisements, 54.3%). Less affluent locations were serviced by greater proportions of taxicabs carrying cigarette advertisements compared with more affluent locations (odds ratio = 2.08, 95% confidence interval = 1.18-3.68).

CONCLUSIONS

Taxicabs represent a major form of exposure to cigarette advertising in Boston.