[Breast cancer: dangers of alleged certainties]. / Cancer du sein: danger des certitudes prétendues.

The artificial increase of breast cancer incidence is estimated as amounting to 30,000 new cases in the year 2000 in France. This increase would be attributable to a 1.2% lack of specificity for the whole range of diagnostic procedures. Sociologically, it appears that the Hippocratic devise "primum nil nocere" ("first don't harm") has been replaced today by "primum agere" ("act first"). Professionals should give information about both limitations and risks of screening. From an ethical point of view, screening programs justify themselves arguing that "there can't be harm in doing good". Absence of alternative strategies is not a sufficient argument for justifying screening with its uncertain consequences.

[Breast cancer detection and medicalization of public health]. / Dépistage du cancer du sein et médicalisation en santé publique.

The aim of reducing breast cancer mortality announced in the report on health in France published in 1994 strongly implicated the promotion of screening and early surgical treatment. However, this mortality has not evolved significantly in France, although more and more cancers have been found and operated upon. The increased prevalence rates of histological diagnoses of breast cancer obtained from the studies of autopsies published has shown that the screening has discovered non-terminal, benign cancers. It has been estimated that 120 of the surgical operations conducted per day in France in 1999 have been carried out to remove non-terminal, benign cancers. Public health has an ethical responsibility to face in terms of the allocation of resources and must remain vigilant in order to avoid excessive screening and unnecessary interventions.

[A model for evaluating screening tests. The case of colorectal tumors]. / Un modèle pour l'évaluation des tests de dépistage. Le cas des tumeurs colorectales.

The results of numerous studies on screening are restricted to crude estimates of the predictive value of different tests. This is notely the case for early diagnosis of colorectal adenoma and cancer. The reference examination is in principle a total colonoscopy. Usually, it is not performed on the subjects for which the screening test gives a negative result. Moreover, the distribution according to age and sex is not taken into account. Both variables are strongly associated with the prevalence of the disease. After a presentation of the problems arising from screening evaluation performed in such situations, a method is proposed for comparing different tests in several populations. An estimate of the expected number of cases within a fictitious control group matched for age and sex with the people whose the test result is positive is computed according to an hypothesis on the duration of asymptomatic cancer and using available descriptive data on symptomatic cancer incidence and on the prevalence of adenoma in the population. The selection power of the test, i.e. the number of observed cases divided by the number of expected cases, is proposed as a standardized parameter for measuring and comparing the validity of screening tests. The method is illustrated by an example of its application procedure. The discussion stresses the limitations of such an approach.

Leukemia after radiotherapy for first primary cancers of various anatomic sites.

The authors conducted a case-control study designed to evaluate the association between radiotherapy for a first primary cancer and subsequent leukemia risk. Study subjects were selected from four tumor registries (California, Connecticut, Kansas, and Massachusetts). Cases were subjects with two primary cancers; the second cancer was a leukemia diagnosed one year or more after the diagnosis of the first primary cancer. Control subjects were patients with single cancers. Two control subjects were chosen for each case matched for tumor registry, site of the first primary cancer, date of diagnosis of the first primary cancer, age, sex, and duration of survival after the first primary cancer. Separate analyses were carried out for chronic lymphatic leukemia (166 cases) and all other leukemias (232 cases). The relative risk of chronic lymphatic leukemia after radiotherapy was 0.7 and did not differ significantly from unity. For all other leukemias, relative risks were 1.6 after radiotherapy for first primary cancers of all sites, 2.4 after radiotherapy to trunk sites, 2.2 after radiotherapy for breast cancer, and 10.3 after radiotherapy for cancer of the corpus uteri. These relative risks for leukemias other than chronic lymphatic leukemia all differed significantly from unity.

[Evolution of tobacco consumption in 2 towns with intervention programs and 2 control towns in Switzerland]. / Evolution de la consommation de tabac dans 2 villes d'intervention et 2 villes témoins suisses.

The National Research Program 1 A on "Primary Prevention of cardiovascular disease in Switzerland' was designed to determine whether community health education can reduce cardiovascular risk factors in the population. Two communities (12,000 inhabitants each) in the French speaking and two (16,000 inhabitants each) in the German speaking part of the country were selected either for intervention or comparison. Following baseline screening in 1977 (stratified random samples) and the community intervention program (1978-1980), a final assessment on the initial participants was performed at the end of 1980. Amongst the regular smokers, 26,2% stopped during this period in the intervention communities whereas 18,1% did so in the reference cities. 4,7% of non-smokers began to smoke during the same period in the intervention communities whereas 7,8% did so in the reference cities. Plasma thiocyanate measurement suggested reliable answers on smoking status. These results suggest that community health education may be effective in preventing harmful health consequence of smoking.

[The influence of family environment on the evolution of tobacco consumption in 2 trial towns and 2 control towns in Switzerland]. / Influence du milieu familial sur l'évolution de la consommation de tabac dans 2 villes d'intervention et 2 villes témoins suisses.

As part of a study on cardiovascular risk factor modification in four Swiss cities (National Research Program 1A, "Primary Prevention of Cardiovascular Disease in Switzerland") between 1977 and 1981, the influence of family members on changes in tobacco consumption was investigated. In this study there were two intervention cities, with a community health education program, and two reference cities. The net decrease of regular smokers was significantly more important in the intervention cities (-3.6%, p less than 0.05), however there was no significantly different pattern for family members. In contrast, there was a significant influence among adult family members both for the decrease (p = 0.0001) and the increase (p less than 0.005) in tobacco consumption.

[Prevention of coronary disease]. / Prévention des maladies coronariennes.

Primary prevention of ischemic heart disease concerns the entire community. The Swiss National Research Program on the Prevention of Cardiovascular Disease has promoted and evaluated prevention activities at town level in the Swiss towns of Nyon and Aarau. Local physicians have played an essential role in establishing a prevention centre involving health professionals, the majority of whom are nonphysicians. Experience at Nyon and Aarau well shows how medical practice and preventive centre complement each other, particularly in improving diet, monitoring blood pressure and reducing tobacco consumption.

[Prevalence of exposure to cardiovascular risk factors in 4 Swiss cities]. / Prévalence de l'exposition aux facteurs de risque des maladies cardio-vasculaires dans quatre villes suisses.

Risk factors for cardiovascular diseases were measured in a sample of 3665 adults between 16 and 70 years of age in four Swiss cities. 54.7% of men and 37.6% of women had either blood pressure values above 160/95 mm Hg or smoked at least 8 g tobacco per day, or had plasma cholesterol exceeding 260 mg/dl (6.73 mmol/l). The statistical associations between the three factors were studied with the following results: direct relation between hypertension and hypercholesterolemia - the odd ratio standardized for age according to Mantel-Haenszel (ORmh) = 2.7 with a 95% confidence interval (IC95) = 1.8 to 4.1 - an inverse relation between hypertension and tobacco consumption - ORmh = 0.59, IC95 = 0.38 to 0.92. In order to investigate the variables associated with exposure to all three factors, an age-specific index of risk was calculated for each person using the multiple logistic function obtained in the Framingham study. In males, this index was elevated in subjects who were sedentary, obese and alcohol consumers, subjects who ate less than three meals a day and subjects who lived alone. The index was elevated in women who were obese, who ate less than three meals a day and in women living alone or without children. The mortality rate for ischemic heart diseases in the four towns was compared with known risk factors and with alcohol consumption. It appears that for both sexes the larger the population regularly drinking a moderate quantity of wine, the lower the mortality rate. The importance of a multifactorial approach to the prevention of cardiovascular diseases is emphasized.

[Distribution of plasma cholesterol in 4 Swiss cities]. / Distribution du cholestérol plasmatique dans quatre villes suisses.

As part of the Swiss National Research Programme on Primary Prevention of Cardiovascular Diseases, plasma cholesterol was determined in 7947 adults of all ages. The distribution of the values obtained in the four Swiss cities investigated is given by age, sex and nationality. Percentile graphs of the whole sample show the influence of age for each sex. On the basis of these results it is estimated that amongst people aged 16-69 years living Switzerland, 7.4% of the men and 8.4% of the women can be expected to have a plasma cholesterol level above 280 mg/dl (7.25 mmol/l). The different relationships between plasma cholesterol and other factors such as consumption of tobacco or alcohol and body mass index were investigated. The latter shows a significant correlation coefficient (r = 0.2, p less than 0.001) for each sex, for the age group 25-44 and for each of the cities. Alcohol consumption is also directly associated with total blood cholesterol. The role of this factor is discussed in relation to the differences in plasma cholesterol observed between the cities.