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Biomedical subjects

R Peto

Publications and source records attributed to R Peto.

At least 109 records · Page 6Linked to original sources
PubMed1994

Cause-specific mortality in long-term survivors of breast cancer who participated in trials of radiotherapy.

PURPOSE: To examine long-term cause-specific mortality in patients irradiated for breast cancer as part of a randomized clinical trial. PATIENTS AND METHODS: We studied all available information from randomized trials initiated before 1975 in which radiotherapy was the randomized option and surgery was the same for both treatment arms. Eight such trials were identified. RESULTS: The increased all-cause mortality rate in 10-year survivors previously reported is no longer significant, although a numerical difference in favor of non-irradiated patients remains. This result was strongly influenced by the earliest trials, and more recent trials have found a nonsignificant net benefit in overall mortality associated with radiation therapy. An excess of cardiac deaths was apparent in both early and more recent trials (P < .001), but this was offset by a reduced number of deaths due to breast cancer, especially in more recent trials. CONCLUSION: The reduction of breast cancer deaths suggests that radiation therapy may have a value beyond the clearly established improvements obtainable for local control. Use of techniques that minimize cardiac dose is important in reducing the risks of adjuvant radiotherapy, especially in good-prognosis patients.

Breast Neoplasms↗
PubMed1993

Geographic association between urinary excretion of N-nitroso compounds and oesophageal cancer mortality in China.

Overnight urine samples were collected from approximately 60 male adults in each of 69 counties of China in 1989. Two specimens were collected from each subject--one after a loading dose of proline and ascorbic acid and another after a loading dose of proline only. Levels of N-nitrosamino acids and nitrate were measured in urine samples and correlated with cumulative mortality rates for subjects aged between 0 and 64 years in the 1970s. Oesophageal cancer mortality rates were positively and significantly associated with (i) urinary levels of excreted N-nitrosoproline (NPRO) (after proline and ascorbic acid loading or proline loading only), (ii) N-nitrososarcosine levels, and (iii) nitrosation potential (the decrease in the amount of urinary NPRO after adding ascorbic acid to the proline load). There were also positive correlations between the urinary level of NPRO or other N-nitrosamino acids and that of nitrate. The urinary excretion of nitrate was associated with consumption of various nitrate-rich vegetables. The results suggest that N-nitroso compounds (NOC) or other nitrite-derived carcinogens are implicated in the aetiology of oesophageal cancer in China.

Adult↗
PubMed1993

Prolonged infection with hepatitis B virus and association between low blood cholesterol concentration and liver cancer.

OBJECTIVE: To determine whether prolonged infection with hepatitis B virus is associated with a lower blood cholesterol concentration. DESIGN: Cross sectional study. SETTING: 81 villages in rural China with a high prevalence of chronic infection with hepatitis B virus. SUBJECTS: 1556 apparently healthy men aged 35-64 years, randomly selected. MAIN OUTCOME MEASURES: Hepatitis B virus carrier state; plasma concentrations of cholesterol, apolipoprotein B, and apolipoprotein A I. RESULTS: 238 (15%) of the men were positive for hepatitis B surface antigen, indicating that they were chronic carriers. Plasma concentration of cholesterol was 4.2% (0.11 mmol/l) lower among carriers (that is, positive for hepatitis B surface antigen) than among non-carriers (95% confidence interval 0.6% to 8.0% (0.01 to 0.21 mmol/l), p < 0.05), and apolipoprotein B concentration was 7.0% (0.036 g/l) lower (2.8% to 11.2% (0.014 to 0.058 g/l), p < 0.001). In contrast, no association was observed between plasma concentrations of cholesterol or apolipoprotein and hepatitis B that had been eradicated (that is, patient positive for hepatitis B core antibody but negative for hepatitis B surface antigen). CONCLUSIONS: Chronic hepatitis B virus infection, which usually starts in early childhood in China, seems to lead not only to a greatly increased risk of death from liver disease but also to a somewhat lower cholesterol concentration in adulthood. This common cause produces an inverse association between cholesterol concentration and risk of death from liver cancer or from other chronic liver diseases.

Adult↗
PubMed1993

Serum antibodies and subsequent cervical neoplasms: a prospective study with 12 years of follow-up.

Approximately 40,000 blood samples drawn in 1968-1972 by the Social Insurance Institution's mobile clinic in Finland have been stored. Linking cancer incidence data obtained from the Finnish Cancer Registry with this material yielded 32 cases of cervical cancer diagnosed after drawing of the blood sample. These 32 individuals and 64 matched controls were analyzed for serum antibodies indicative of past infection with Chlamydia trachomatis, Neisseria gonorrhoeae, cytomegalovirus, Epstein-Barr virus, and herpes simplex virus type 2. After adjustment for smoking and other sexually transmitted diseases, antibodies to C. trachomatis showed the strongest association with cervical cancer (odds ratio = 5.0 (95% confidence interval 1.6-15.7)), but the numbers were too small for drawing conclusions as to the sexually transmitted diseases with which cervical cancer is most specifically associated.

Adolescent↗
PubMed1992

Mortality from tobacco in developed countries: indirect estimation from national vital statistics.

Prolonged cigarette smoking causes even more deaths from other diseases than from lung cancer. In developed countries, the absolute age-sex-specific lung cancer rates can be used to indicate the approximate proportions due to tobacco of deaths not only from lung cancer itself but also, indirectly, from vascular disease and from various other categories of disease. Even in the absence of direct information on smoking histories, therefore, national mortality from tobacco can be estimated approximately just from the disease mortality statistics that are available from all major developed countries for about 1985 (and for 1975 and so, by extrapolation, for 1995). The relation between the absolute excess of lung cancer and the proportional excess of other diseases can only be approximate, and so as not to overestimate the effects of tobacco it has been taken to be only half that suggested by a recent large prospective study of smoking and death among one million Americans. Application of such methods indicates that, in developed countries alone, annual deaths from smoking number about 0.9 million in 1965, 1.3 million in 1975, 1.7 million in 1985, and 2.1 million in 1995 (and hence about 21 million in the decade 1990-99: 5-6 million European Community, 5-6 million USA, 5 million former USSR, 3 million Eastern and other Europe, and 2 million elsewhere, [ie, Australia, Canada, Japan, and New Zealand]). More than half these deaths will be at 35-69 years of age: during the 1990s tobacco will in developed countries cause about 30% of all deaths at 35-69 (making it the largest single cause of premature death) plus about 14% of all at older ages. Those killed at older ages are on average already almost 80 years old, however, and might have died soon anyway, but those killed by tobacco at 35-69 lose an average of about 23 years of life. At present just under 20% of all deaths in developed countries are attributed to tobacco, but this percentage is still rising, suggesting that on current smoking patterns just over 20% of those now living in developed countries will eventually be killed by tobacco (ie, about a quarter of a billion, out of a current total population of just under one and a quarter billion).

Adult↗
PubMed1992

Statistics of chronic disease control.

Control of the chronic diseases of middle age is increasingly important, in developed and in developing countries, as other causes of premature death decrease. It requires bigger clinical trials, and better epidemiology.

Chronic Disease↗
PubMed1992

Herpes simplex virus type 2 infection and cervical cancer: a prospective study of 12 years of follow-up in Finland.

This study was initiated to investigate the role of past herpes simplex virus type 2 (HSV-2) infection, as determined by serum antibody analysis, in the etiology of cervical neoplasia. Two Finnish registers, the registry of the Social Insurance Institution's Mobile Clinic Survey and the Finnish Cancer Registry, were linked. About 40,000 blood samples were drawn in 1968-72 and stored by the Social Insurance Institution. According to the Cancer Registry, 32 cases of cervical carcinoma or carcinoma in situ for which serum samples were available were diagnosed in this cohort during a follow-up of 12 years (1968-81). The serum samples of these individuals and age matched controls (2:1) from the cohort were analyzed for HSV-2 antibodies. HSV-2 infection as determined by the best available HSV-2 type-specific antibody assay, glycoprotein gG2-ELISA, was not related to cervical neoplasia, i.e., the risk of cervical neoplasia among the HSV-2 positive women was not higher than that among the negative ones (smoking-adjusted relative risk = 0.5, 95 percent confidence interval = 0.2-1.6). The results do not support the hypothesis that HSV-2 is an etiologic agent for cervical neoplasia.

Adolescent↗