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Richard Peto

Publications and source records attributed to Richard Peto.

34 records · Page 2Linked to original sources
PubMed2004

Breast cancer and abortion: collaborative reanalysis of data from 53 epidemiological studies, including 83?000 women with breast cancer from 16 countries.

BACKGROUND: The Collaborative Group on Hormonal Factors in Breast Cancer has brought together the worldwide epidemiological evidence on the possible relation between breast cancer and previous spontaneous and induced abortions. METHODS: Data on individual women from 53 studies undertaken in 16 countries with liberal abortion laws were checked and analysed centrally. Relative risks of breast cancer--comparing the effects of having had a pregnancy that ended as an abortion with those of never having had that pregnancy--were calculated, stratified by study, age at diagnosis, parity, and age at first birth. Because the extent of under-reporting of past induced abortions might be influenced by whether or not women had been diagnosed with breast cancer, results of the studies--including a total of 44000 women with breast cancer--that used prospective information on abortion (ie, information that had been recorded before the diagnosis of breast cancer) were considered separately from results of the studies--including 39000 women with the disease--that used retrospective information (recorded after the diagnosis of breast cancer). FINDINGS: The overall relative risk of breast cancer, comparing women with a prospective record of having had one or more pregnancies that ended as a spontaneous abortion versus women with no such record, was 0.98 (95% CI 0.92-1.04, p=0.5). The corresponding relative risk for induced abortion was 0.93 (0.89-0.96, p=0.0002). Among women with a prospective record of having had a spontaneous or an induced abortion, the risk of breast cancer did not differ significantly according to the number or timing of either type of abortion. Published results on induced abortion from the few studies with prospectively recorded information that were not available for inclusion here are consistent with these findings. Overall results for induced abortion differed substantially between studies with prospective and those with retrospective information on abortion (test for heterogeneity between relative risks: chi2(1) =33.1, p<0.0001). INTERPRETATION: Pregnancies that end as a spontaneous or induced abortion do not increase a woman's risk of developing breast cancer. Collectively, the studies of breast cancer with retrospective recording of induced abortion yielded misleading results, possibly because women who had developed breast cancer were, on average, more likely than other women to disclose previous induced abortions.

Abortion, Induced↗
PubMed2004

Effects of cholesterol-lowering with simvastatin on stroke and other major vascular events in 20536 people with cerebrovascular disease or other high-risk conditions.

BACKGROUND: Lower blood cholesterol concentrations have consistently been found to be strongly associated with lower risks of coronary disease but not with lower risks of stroke. Despite this observation, previous randomised trials had indicated that cholesterol-lowering statin therapy reduces the risk of stroke, but large-scale prospective confirmation has been needed. METHODS: 3280 adults with cerebrovascular disease, and an additional 17256 with other occlusive arterial disease or diabetes, were randomly allocated 40 mg simvastatin daily or matching placebo. Subgroup analyses were prespecified of first "major vascular event" (ie, non-fatal myocardial infarction or coronary death, stroke of any type, or any revascularisation procedure) in prior disease subcategories. Subsidiary outcomes included any stroke, and stroke sub-type. Comparisons are of all simvastatin-allocated versus all placebo-allocated participants (ie, "intention-to-treat"), which yielded an average difference in LDL cholesterol of 1.0 mmol/L (39 mg/dL) during the 5-year treatment period. FINDINGS: Overall, there was a highly significant 25% (95% CI 15-34) proportional reduction in the first event rate for stroke (444 [4.3%] simvastatin vs 585 [5.7%] placebo; p<0.0001), reflecting a definite 28% (19-37) reduction in presumed ischaemic strokes (p<0.0001) and no apparent difference in strokes attributed to haemorrhage (51 [0.5%] vs 53 [0.5%]; rate ratio 0.95 [0.65-1.40]; p=0.8). In addition, simvastatin reduced the numbers having transient cerebral ischaemic attacks alone (2.0% vs 2.4%; p=0.02) or requiring carotid endarterectomy or angioplasty (0.4% vs 0.8%; p=0.0003). The reduction in stroke was not significant during the first year, but was already significant (p=0.0004) by the end of the second year. Among patients with pre-existing cerebrovascular disease there was no apparent reduction in the stroke rate, but there was a highly significant 20% (8-29) reduction in the rate of any major vascular event (406 [24.7%] vs 488 [29.8%]; p=0.001). The proportional reductions in stroke were about one-quarter in each of the other subcategories of participant studied, including: those with coronary disease or diabetes; those aged under or over 70 years at entry; and those presenting with different levels of blood pressure or lipids (even when the pretreatment LDL cholesterol was below 3.0 mmol/L [116 mg/dL]). INTERPRETATION: Much larger numbers of people in the present study suffered a stroke than in any previous cholesterol-lowering trial. The results demonstrate that statin therapy rapidly reduces the incidence not only of coronary events but also of ischaemic strokes, with no apparent effect on cerebral haemorrhage, even among individuals who do not have high cholesterol concentrations. Allocation to 40 mg simvastatin daily reduced the rate of ischaemic strokes by about one-quarter and so, after making allowance for non-compliance in the trial, actual use of this regimen would probably reduce the stroke rate by about a third. HPS also provides definitive evidence that statin therapy is beneficial for people with pre-existing cerebrovascular disease, even if they do not already have manifest coronary disease.

Adult↗
PubMed2004

Blood biochemistry and the risk of cancer.

A longitudinal study based on a serum sample bank was carried out in Finland to find out the association between biochemical substances and the subsequent risk of cancer. The objective was to evaluate the consistency between means of individually estimated levels of these compounds and levels based on pooling. Levels of alpha-tocopherol, beta-carotene, retinol, retinol-binding protein, and ceruloplasmin were estimated by primary site and sex and partly by age and morphology. The concentrations in pooled samples were consistently lower than the averages of the individual samples. On the basis of individual samples, all the five biochemical compounds had a rather consistent protective effect on the risk of cancers at most primary sites. This protective effect disappeared in the pool analyses, and more than half of exposure contrasts showed an opposite sign. For ceruloplasmin, the effect of pooling was smaller but not negligible. The results of this study emphasize the demand to standardize the collecting, handling, and analysing of samples in serum banks. They are, furthermore, consistent with the hypothesis that pooling of biochemical samples affects the levels of the substances and may affect the conclusions of epidemiological studies on causes of diseases.

Biomarkers, Tumor↗
PubMed2003

Smoking and liver cancer in China: case-control comparison of 36,000 liver cancer deaths vs. 17,000 cirrhosis deaths.

Liver cancer and liver cirrhosis are common causes of death in China, where chronic lifelong hepatitis B infection is a major cause of both diseases. To help determine whether smoking is a cofactor for the development of liver cancer, we ascertained retrospectively the smoking habits of 36,000 adults who had died from liver cancer (cases) and 17,000 who had died from cirrhosis (controls) in 24 Chinese cities and 74 rural counties. Calculations of the smoker vs. nonsmoker risk ratios (RR) for liver cancer mortality were standardised for age and locality. Among adult men (aged 35+) there was a 36% excess risk of death from liver cancer among smokers (smoker vs. nonsmoker standardised risk ratio [RR] =1.36, with 95% confidence interval [CI] 1.29-1.43, 2p<0.00001; attributable fraction 18%). In the general male population this indicates absolute risks of death from liver cancer before age 70 of about 4% in smokers and 3% in nonsmokers (in the absence of other causes). Most liver cancer, however, occurs among the 10-12% of men with haematological evidence of chronic hepatitis B infection, so among them the corresponding risks would be about 33% in smokers and 25% in nonsmokers. The RR was approximately independent of age, was similar in urban and rural areas, was not significantly related to the age when smoking started but was significantly (p<0.001) greater for cigarette smokers than for smokers of other forms of tobacco. Among men who smoked only cigarettes, the RR was significantly (p<0.001 for trend) related to daily consumption, with a greater hazard among those who smoked 20/day (RR 1.50, 95% CI 1.39-1.62) than among those who smoked fewer (mean 10/day: RR=1.32, 95% CI 1.23-1.41). Smoking was also associated with a significant excess of liver cancer death in women (RR 1.17, 95% CI 1.06-1.29, 2p=0.003; attributable fraction 3%), but fewer women (17%) than men (62%) were smokers, and their cigarette consumption per smoker was lower. Among women who smoked only cigarettes, there was a significantly greater hazard among those who smoked at least 20/day (mean 22/day: RR=1.45, 95% CI 1.18-1.79) than among those who smoked fewer (mean 8/day: RR=1.09, 95% CI 0.94-1.25). These associations indicate that tobacco is currently responsible for about 50,000 liver cancer deaths each year in China, chiefly among men with chronic HBV infection.

Adult↗
PubMed2003

Smoking and mortality from tuberculosis and other diseases in India: retrospective study of 43000 adult male deaths and 35000 controls.

BACKGROUND: In India most adult deaths involve vascular disease, pulmonary tuberculosis, or other respiratory disease, and men have smoked cigarettes or bidis (which resemble small cigarettes) for several decades. The study objective was to assess age-specific mortality from smoking among men (since few women smoke) in urban and in rural India. METHODS: We did a case-control study of the smoking habits of 27000 urban and 16000 rural men who had died in the state of Tamil Nadu, southern India, from medical causes (ie, any cause other than accident, homicide, or suicide), and of 20000 urban and 15000 rural male controls. The main analyses are of mortality at ages 25-69 years. FINDINGS: In the urban study area, the death rates from medical causes of ever smokers were double those of never smokers (standardised risk ratio at ages 25-69 years 2.1 [95% CI 2.0-2.2]). The risks were substantial both for cigarette smoking (the main urban habit) and for bidi smoking. Of this excess mortality among smokers, a third involved respiratory disease, chiefly tuberculosis (4.5 [4.0-5.0], smoking-attributed fraction 61%), a third involved vascular disease (1.8 [1.7-1.9], smoking-attributed fraction 24%), 11% involved cancer (2.1 [1.9-2.4], smoking-attributed fraction 32%), chiefly of the respiratory or upper digestive tracts, and 14% involved alcoholism or cirrhosis (3.3 [2.9-3.8], not attributed to smoking). Among ever smokers, the absolute excess mortality from tuberculosis was substantial throughout the age range 25-69 years. (A separate survey of 250000 men living in the urban study area found that ever smokers are three times as likely as never smokers to report a history of tuberculosis, corresponding to a higher rate of progression of chronic subclinical infection to clinical disease.) The proportional excesses of respiratory, vascular, and neoplastic mortality at ages 25-69 years among ever smokers in the urban study area were replicated, each with similarly narrow CI for the risk ratio, in the rural study area (where bidi smoking predominated), and are taken to be largely or wholly causal. For urban and for rural death from medical causes at older ages (> or =70 years), the standardised risk ratio was 1.3. INTERPRETATION: Smoking, which increases the incidence of clinical tuberculosis, is a cause of half the male tuberculosis deaths in India, and of a quarter of all male deaths in middle age (plus smaller fractions of the deaths at other ages). At current death rates, about a quarter of cigarette or bidi smokers would be killed by tobacco at ages 25-69 years, those killed at these ages losing about 20 years of life expectancy. Overall, smoking currently causes about 700000 deaths per year in India, chiefly from respiratory or vascular disease: about 550000 men aged 25-69 years, about 110000 older men, and much smaller numbers of women (since few women smoke).

Adult↗
PubMed2003

MRC/BHF Heart Protection Study of cholesterol-lowering with simvastatin in 5963 people with diabetes: a randomised placebo-controlled trial.

BACKGROUND: Individuals with diabetes are at increased risk of cardiovascular morbidity and mortality, although typically their plasma concentrations of LDL cholesterol are similar to those in the general population. Previous evidence about the effects of lowering cholesterol in people with diabetes has been limited, and most diabetic patients do not currently receive cholesterol-lowering therapy despite their increased risk. METHODS: 5963 UK adults (aged 40-80 years) known to have diabetes, and an additional 14573 with occlusive arterial disease (but no diagnosed diabetes), were randomly allocated to receive 40 mg simvastatin daily or matching placebo. Prespecified analyses in these prior disease subcategories, and other relevant subcategories, were of first major coronary event (ie, non-fatal myocardial infarction or coronary death) and of first major vascular event (ie, major coronary event, stroke or revascularisation). Analyses were also conducted of subsequent vascular events during the scheduled treatment period. Comparisons are of all simvastatin-allocated versus all placebo-allocated participants (ie, intention to treat), which yielded an average difference in LDL cholesterol of 1.0 mmol/L (39 mg/dL) during the 5-year treatment period. FINDINGS: Both among the participants who presented with diabetes and among those who did not, there were highly significant reductions of about a quarter in the first event rate for major coronary events, for strokes, and for revascularisations. For the first occurrence of any of these major vascular events among participants with diabetes, there was a definite 22% (95% CI 13-30) reduction in the event rate (601 [20.2%] simvastatin-allocated vs 748 [25.1%] placebo-allocated, p<0.0001), which was similar to that among the other high-risk individuals studied. There were also highly significant reductions of 33% (95% CI 17-46, p=0.0003) among the 2912 diabetic participants who did not have any diagnosed occlusive arterial disease at entry, and of 27% (95% CI 13-40, p=0.0007) among the 2426 diabetic participants whose pretreatment LDL cholesterol concentration was below 3.0 mmol/L (116 mg/dL). The proportional reduction in risk was also about a quarter among various other subcategories of diabetic patient studied, including: those with different duration, type, or control of diabetes; those aged over 65 years at entry or with hypertension; and those with total cholesterol below 5.0 mmol/L (193 mg/dL). In addition, among participants who had a first major vascular event following randomisation, allocation to simvastatin reduced the rate of subsequent events during the scheduled treatment period. INTERPRETATION: The present study provides direct evidence that cholesterol-lowering therapy is beneficial for people with diabetes even if they do not already have manifest coronary disease or high cholesterol concentrations. Allocation to 40 mg simvastatin daily reduced the rate of first major vascular events by about a quarter in a wide range of diabetic patients studied. After making allowance for non-compliance, actual use of this statin regimen would probably reduce these rates by about a third. For example, among the type of diabetic patient studied without occlusive arterial disease, 5 years of treatment would be expected to prevent about 45 people per 1000 from having at least one major vascular event (and, among these 45 people, to prevent about 70 first or subsequent events during this treatment period). Statin therapy should now be considered routinely for all diabetic patients at sufficiently high risk of major vascular events, irrespective of their initial cholesterol concentrations.

Adult↗
PubMed2003

Large-scale evidence that the cardiotoxicity of smoking is not significantly modified by the apolipoprotein E epsilon2/epsilon3/epsilon4 genotype.

Results from two small studies, involving a total of only 174 cases, have suggested that the increased risk of coronary heart disease conferred by cigarette smoking is substantially affected by genotype at the apolipoprotein E (APOE) epsilon2/epsilon3/epsilon4 polymorphism. We have established APOE genotypes in 4484 patients with acute myocardial infarction diagnosed before the age of 55 years for male and 65 years for female patients, and in 5757 controls with no history of cardiovascular disease. On average, the hazard ratio for myocardial infarction was 1.17 (95% CI 1.09-1.25; p<0.00001) per stepwise change from epsilon3/2 to epsilon3/3 to epsilon3/4 genotype. Among individuals in this study with known cigarette smoking status, the hazard ratio for myocardial infarction in smokers versus non-smokers was 4.6 (4.2-5.1). There was, however, no significant difference between the smoker/non-smoker hazard ratios for those with different APOE genotypes (chi2(2)=0.69; p=0.7). When differences in risk between different genotypes are not extreme (as with this APOE polymorphism), reliable assessment of hypothesised gene-environment interactions will often require the study of many thousands of disease cases.

Aged↗
PubMed2003

Stability of plasma analytes after delayed separation of whole blood: implications for epidemiological studies.

BACKGROUND: Large blood-based epidemiological studies require simple, cost-effective sample collection methods. Immediate sample separation or rapid transport of chilled blood samples to a central laboratory may be impractical or prohibitively expensive. To assess the feasibility and reliability of transporting blood samples over several days at ambient temperature (e.g. by mail), we evaluated the stability of various plasma analytes in samples stored at room temperature or chilled. METHODS: Multiple vacutainers of blood, containing EDTA and aprotinin as preservative, were drawn from 12 volunteers and stored at 21 degrees C or 4 degrees C. Immediately after collection and 1, 2, 3, 4, and 7 days later, vacutainers stored at each temperature were centrifuged, and the plasma was aliquoted and stored at -80 degrees C. Subsequently, all aliquots from each individual were analysed in one analytical run for a range of chemistries. RESULTS: In whole blood stored at room temperature for up to 7 days, concentrations of albumin, apolipoproteins A1 and B (apoA1 and apoB), cholesterol, high density lipoprotein (HDL), total protein, and triglycerides changed by less than 4%, and low density lipoprotein (LDL) by less than 7%. Whilst alanine transaminase (ALT), creatine kinase (CK), creatinine, and gamma-glutamyl transferase (GGT) concentrations changed substantially at room temperature, there was less than 4% change during chilled storage up to 7 days. By contrast, aspartate transaminase (AST) concentrations increased markedly under both conditions. CONCLUSIONS: A wide range of important analytes, including lipids, change by only a few per cent in whole blood during storage at room temperature for several days. Mailed transport of whole blood samples may, therefore, be a simple and cost-effective option for large-scale epidemiological studies.

Alanine Transaminase↗
PubMed2002

Age-specific relevance of usual blood pressure to vascular mortality: a meta-analysis of individual data for one million adults in 61 prospective studies.

BACKGROUND: The age-specific relevance of blood pressure to cause-specific mortality is best assessed by collaborative meta-analysis of individual participant data from the separate prospective studies. METHODS: Information was obtained on each of one million adults with no previous vascular disease recorded at baseline in 61 prospective observational studies of blood pressure and mortality. During 12.7 million person-years at risk, there were about 56000 vascular deaths (12000 stroke, 34000 ischaemic heart disease [IHD], 10000 other vascular) and 66000 other deaths at ages 40-89 years. Meta-analyses, involving "time-dependent" correction for regression dilution, related mortality during each decade of age at death to the estimated usual blood pressure at the start of that decade. FINDINGS: Within each decade of age at death, the proportional difference in the risk of vascular death associated with a given absolute difference in usual blood pressure is about the same down to at least 115 mm Hg usual systolic blood pressure (SBP) and 75 mm Hg usual diastolic blood pressure (DBP), below which there is little evidence. At ages 40-69 years, each difference of 20 mm Hg usual SBP (or, approximately equivalently, 10 mm Hg usual DBP) is associated with more than a twofold difference in the stroke death rate, and with twofold differences in the death rates from IHD and from other vascular causes. All of these proportional differences in vascular mortality are about half as extreme at ages 80-89 years as at ages 40-49 years, but the annual absolute differences in risk are greater in old age. The age-specific associations are similar for men and women, and for cerebral haemorrhage and cerebral ischaemia. For predicting vascular mortality from a single blood pressure measurement, the average of SBP and DBP is slightly more informative than either alone, and pulse pressure is much less informative. INTERPRETATION: Throughout middle and old age, usual blood pressure is strongly and directly related to vascular (and overall) mortality, without any evidence of a threshold down to at least 115/75 mm Hg.

Adult↗
PubMed2002

Verbal autopsy of 48 000 adult deaths attributable to medical causes in Chennai (formerly Madras), India.

BACKGROUND: In the city of Chennai, India, registration of the fact of death is almost complete but the cause of death is often inadequately recorded on the death certificate. A special verbal autopsy (VA) study of 48 000 adult deaths in Chennai during 1995-97 was conducted to arrive at the probable underlying cause of death and to measure cause specific mortality rates for Chennai. METHODS: Trained non-medical graduates with at least 15 years of formal education interviewed the surviving family members or an associate of the deceased to write a report on the complaints, symptoms, signs, duration and treatment details of illness prior to death. Each report was reviewed centrally by two physicians independently. The reliability was assessed by comparing deaths attributed to cancer by VA with records in Vital Statistics Department and Chennai Cancer Registry. RESULTS: The VA reduced the proportion of deaths attributed to unspecified medical causes and unknown causes from 37% to 7% in early adult life and middle age (25-69 yrs) and has yielded fewer unspecified causes (only 10%) than the death certificate. The sensitivity of VA to identify cancer was 94% in the age group 25-69. CONCLUSION: VA is practicable for deaths in early adult life or middle age and is of more limited value in old age. A systematic program of VA of a representative sample of deaths could assign broad causes not only to deaths in childhood (as has previously been established) but also to deaths in early adult life and middle age.

Adult↗
PubMedDate not supplied

The MRC/BHF Heart Protection Study: preliminary results.

The Heart Protection Study (HPS), with over 20,500 subjects, is the largest trial of statin therapy ever conducted. It provides important and definitive new information on women, the elderly, diabetics, and people with low baseline cholesterol pre-treatment and those with prior occlusive non-coronary vascular disease. It is a prospective double blind randomised controlled trial with a 2 x 2 factorial design investigating prolonged use (>5 years) of simvastatin 40 mg and a cocktail of antioxidant vitamins (650 mg vitamin E, 250 mg vitamin C and 20 mg beta-carotene). The HPS specifically included patients with high risk for coronary heart disease (CHD) but characteristics that excluded them from participation in previous statin trials. Simvastatin 40 mg treatment showed benefit across all patient groups regardless of age, gender or baseline cholesterol value and proved safe and well tolerated. Results show a 12% reduction in total mortality, a 17% reduction in vascular mortality, a 24% reduction in CHD events, a 27% reduction in all strokes and a 16% reduction in non-coronary revascularisations. Among high-risk patients in this western population (with a minimum total cholesterol [TC] > or = 3.5 mmol/l at entry) there appears to be no threshold cholesterol value below which statin therapy is not associated with benefit; even among those with pre-treatment cholesterol levels below current national recommended targets. Over the 5.5 year study period patients and their doctors were encouraged to add an active non-study statin to the study regimen if they wished to do so. Thus the trial eventually had only two-thirds complying with the original intention-to-treat design. Nevertheless, results were highly significant for the study statin--simvastatin 40 mg once daily. Preliminary results of the HPS are negative for the antioxidant vitamin cocktail but provide reassurance that vitamins do no harm.

Aged↗