The relation between dietary vitamin A and the risk of invasive cervical cancer was evaluated using data from a hospital-based case-control study of 191 women with cervical cancer and 191 age-matched controls. There was no association between dietary retinoids and cervical cancer risk. Intake of dietary beta-carotene, on the other hand, was inversely and strongly related to the risk of cervical cancer. Compared to risks for women reporting a monthly intake of 150,000 or more international units (IU) of beta-carotene, the estimated relative risks for those with 100,000 to 149,000 and those with less than 100,000 IU per month were 2.8 and 6.1 respectively. The inverse association was not explained by any of the major identified risk factors for cervical cancer (including indicators of socio-economic status or sexual habits), or by differences in general characteristics and other lifestyle habits between cases and controls. Thus, although the uncertainties of the vitamin A measurements used are substantial, these findings support the hypothesis that dietary beta-carotene-or some related aspect of a vegetable-rich diet-is protective against invasive cervical cancer.

A positive association between the use of oral contraceptives and the risk of cervical neoplasia has been suggested by different sources. This paper examines epidemiologic evidence on this issue through pooled computation of relative risks emerging from 21 studies, subdivided into three main categories: studies based on routine cytologic screening programs, case-control investigations and prospective studies. The pooled estimates of the relative risks for ever vs never use of oral contraceptives were broadly similar and slightly above unity (1.4 from cytologic screening programs, 1.1 from case-control and 1.4 from prospective studies). The risk increased with duration of use and, generally, lower relative risk estimates derived from the older studies, necessarily based on short-term use of oral contraceptives. A particularly limited increase in risk was apparent from case-control investigations. Furthermore, when allowance was made for the major covariates (mostly indicators of sexual habits), a noticeable decrease in the excess risk was evident. In conclusion, although statistical significance of moderate differences in risk can be obtained by pooling data from several studies, a risk of the magnitude of that for the association between oral contraceptives and cervical neoplasia may well be due to bias and confounding. In addition, since sexual behavior only indicates the probability of having been exposed to some sexually transmitted agent (most likely human papilloma virus), the greatest additional contribution may come from a case-control study in which adjustment for such exposure is possible.

A method of graphic representation of time factors in cancer mortality is presented, based on different tonalities of grey applied to the surface of the matrix defined by various age-specific rates. It is illustrated using mortality data from cancers of the mouth or pharynx, oesophagus, larynx and lung in Italian and Swiss males. Progressively more complex regression surface equations are defined, on the basis of two independent variables (age and cohort) and a dependent one (each age-specific rate). General patterns of trends were thus identified, showing important similarities in cohort and period effects, but also noticeable differences in time-related factors in mortality from various neoplasms of the upper digestive and respiratory tract. For instance, there were declines in mortality from cancers of the mouth or pharynx in the oldest age groups, whereas rates were appreciably upwards at younger and middle age, particularly in Italy. Likewise, cancers of the oesophagus and, chiefly, of the larynx were substantially increasing, on a cohort basis, in oldest Italian males. Temporal pattern for laryngeal cancer in Italy was similar to that of lung cancer, thus suggesting that (cigarette) smoking has a greater impact on this cancer site as compared with alcohol. However, it is difficult to explain, on this basis alone, the totally diverging pattern for cancer of the larynx (downwards) and of the lung (upwards) observed among older Swiss males. These examples indicate that trend surface models are a useful summary guide to illustrate and understand the general patterns of age, period and cohort effects in cancer mortality.

The mortality experience of a cohort of chrysotile miners employed since 1946 in Balangero, northern Italy was updated to the end of 1987 giving a total of 427 deaths out of 27,010 man-years at risk. A substantial excess mortality for all causes (standardised mortality ratio (SMR) = 149) was found, mainly because of high rates for some alcohol related deaths (hepatic cirrhosis, accidents). For mortality from cancer, however, the number of observed deaths (82) was close to that expected (76.2). The SMR was raised for oral cancer (SMR 231 based on six deaths), cancer of the larynx (SMR 267 based on eight deaths), and pleura (SMR 667 based on two deaths), although the excess only reached statistical significance for cancer of the larynx. Rates were not increased for lung, stomach, or any other type of cancer. No consistent association was seen with duration or cumulative dust exposure (fibre-years) for oral cancer, but the greatest risks for laryngeal and pleural cancer were in the highest category of duration and degree of exposure to fibres. Although part of the excess mortality from laryngeal cancer is probably attributable to high alcohol consumption in this group of workers, the data suggest that exposure to chrysotile asbestos (or to the fibre balangeroite that accounts for 0.2-0.5% of total mass in the mine) is associated with some, however moderate, excess risk of laryngeal cancer and pleural mesothelioma. The absence of excess mortality from lung cancer in this cohort is difficult to interpret.

Correspondence to: C La Vecchia Abstract Objective To assess the relationship be tween cigarette smoking and the risk of acute myocardial infarction in Argen tina. Design Hospital-based case-control study conducted between 1984 and 1989 in Buenos Aires. Main outcome measures were multiple logistic regression analysis of relative risk (RR) estimates, and the corresponding 95% confidence intervals (CI), according to smoking status. Al lowance was made for sex, age, education, body mass index, diabetes, hypertension, and family history of coronary heart disease. Setting-A network including 11 coron ary care units from major hospitals in Buenos Aires. Subjects Cases were 1000 patients with acute myocardial infarction. Controls were 1000 patients admitted to the same network of hospitals with a wide spec trum of acute disorders unrelated to smoking or to known or suspected risk factors for myocardial infarction. Results After allowance for major risk factors for myocardial infarction, com pared to lifelong non-smokers, the RRs were 1.6 (95% CI = 1.1 to 2.4) for current smokers of less than 15 cigarettes per day, 2.2 (95% CI = 1.6 to 3.0) for smokers of 15-24, and 5.9 (95% CI = 4.2 to 8.3) for smokers of 25 or more cigarettes per day. The RR was 1.5 (95% CI = 1.1 to 2.0) for ex-smokers who had been abstinent for at least one year. The RR at younger age (30-44 years) was 10.3 (95% CI = 4.3 to 24.9) for heavy smokers (^ 25 cigarettes per day), and declined with advancing age. Conclusions Cigarette smoking is an independent and important risk factor for acute myocardial infarction, and about 40% of cases in this Argentinian population (and over 55% of cases under age 55) are attributable to it. {Tobacco Control 1993; 2: 127-131)

The relationship between beer consumption and the risk of colon and rectal cancer was considered in a case-control study conducted in northern Italy. The study was based on 828 histologically confirmed incident cases of colon cancer, 498 of rectal cancer, and 2,024 controls in hospital for a wide spectrum of acute, nonneoplastic, nonalcohol-related diseases. Beer drinking was reported by 6% of colon cancer cases, 7% of rectal cancer cases, and 10% of controls; regular beer drinkers (> or = 1 drinks/day) made up 2.6% of colon cancer cases, 3.2% of rectal cancer cases, and 4.1% of controls. Thus the multivariate relative risks (RR) for irregular drinkers were 0.6 [95% confidence interval (CI) 0.4-1.0] for colon and 0.7 (95% CI 0.4-1.2) for rectum. Corresponding values for regular drinkers were 0.7 (95% CI 0.4-1.2) for colon and 0.9 (95% CI 0.5-1.5) for rectal cancer. Despite the low frequency of beer drinking in this study, and hence its limited statistical power, the originality of the population in terms of colorectal cancer incidence, patterns of risk factor exposure, and the large dataset provide interesting and useful confirmation that moderate beer drinking is not associated with elevated colon or rectal cancer risk.

The relationship between dietary factors and the risk of breast cancer was investigated in a case-control study conducted in the Canton of Vaud, Switzerland as a pilot phase for a larger cooperative study within the SEARCH Programme of the International Agency for Research on Cancer (Lyon, France). A total of 107 incident, histologically confirmed cases of breast cancer and 318 controls admitted to hospital for acute, nonhormone-related, gynecological, metabolic, or neoplastic disorders were interviewed. Significant direct trends in risk were observed with total energy intake [relative risk (RR) for highest vs. lowest intake tertile = 1.9] and, after allowance for energy intake, with frequency of consumption of various types of meat (RR = 2.1 for the highest tertile), cheese (RR = 2.7), and alcohol (RR = 2.1). Significant protections, on the order of 40-60% reductions for the highest vs. lowest consumption tertile, were conferred by total green vegetable consumption, selected types of vegetables and fruits (cucumbers, onions, pears), and a summary index of beta-carotene intake (RR = 0.4 for highest consumption tertile). Thus the present study confirmed the existence of an unfavorable dietary pattern for breast cancer risk (characterized by high-calorie, selected sources of animal fat and alcohol intake). Moreover, a significant protection could be gained by consuming a diet rich in vegetables and perhaps fruits.