Circulating levels of adiponectin, a hormone with insulin-sensitizing properties, are decreased in conditions related to obesity and hyperinsulinemia, which are recognized risk factors for endometrial cancer. Eighty-seven cases with incident, histologically confirmed endometrial cancer and 132 controls admitted for acute, nonneoplastic diseases were interviewed in northeastern Italy between 1999 and 2002, and blood samples were collected. Levels of adiponectin were evaluated in samples by means of a RIA. An inverse association with endometrial cancer risk emerged for plasma adiponectin levels [odds ratio (OR), 0.42; 95% confidence interval, 0.19-0.94] when comparing the highest vs. the lowest tertiles. Similar results emerged for serum adiponectin (OR, 0.30; 95% confidence interval, 0.14-0.68). The association was stronger in pre- than in postmenopausal women, but no significant heterogeneity was observed across strata of body mass index (BMI) or parity. BMI and adiponectin showed independent effects on the risk of endometrial cancer according to a multiplicative model (OR, 6.45 in the highest level of BMI and in the lowest one of adiponectin).
Risk factors for colon cancer have essentially been considered in terms of relative risks. From a public health viewpoint, however, their impact depends not only on the strength of the association, but also on the distribution of exposures in the population. Thus we used data from a case-control study conducted in Italy between 1992 and 1996 to estimate the population-attributable risks (PARs) for colon cancer in relation to educational level, physical activity, energy and vegetable intake, eating frequency, and family history of colorectal cancer. Cases were 1,225 incident, histologically confirmed colon cancer patients admitted to the major teaching and general hospitals in six Italian areas; controls were 4,154 subjects with no history of cancer, admitted to hospitals in the same catchment areas for acute, nonneoplastic diseases. By use of the distribution of the risk factors in the cases and the multivariate relative risk estimates, PARs were computed, i.e., the proportion of colon cancer that would have been avoided if all subjects were moved to the lowest exposure level. The PARs were 12% for high education, 14% for low physical activity, 14% for high energy intake, 22% for low vegetable intake, 7% for high eating frequency, and 8% for a family history of colorectal cancer. These factors together accounted for 56% of colon cancer cases. PARs were similar across age strata. Men had higher PARs for education, physical activity, and their combination, but lower PARs for energy, eating frequency, vegetable intake, and their combination than women. The percentage of colon cancers attributable to all factors considered together was 50% in men and 67% in women. Even if the PAR estimates were based on several arbitrary assumptions on the exposure distribution for various risk factors, available knowledge could, in principle, explain > 50% of cases in this Italian population, thus indicating and quantifying the theoretical scope for prevention.
The relationship between selected aspects of medical history and the risk of primary liver cancer was analyzed in a hospital-based case-control study conducted in Northern Italy on 242 patients with histologically or serologically confirmed hepatocellular carcinoma and 1169 controls in hospital for acute, nonneoplastic, or digestive diseases. Significant associations were observed for clinical history of hepatitis [odds ratio (OR), 3.7; 95% confidence interval (CI), 2.3-5.9], cirrhosis (OR, 16.8; 95% CI, 9.8-28.8), and three or more episodes of transfusion in the past (OR, 2.2; 95% CI, 1.4-4.1). Among other diseases considered, there was a significant association with diabetes (OR, 2.5; 95% CI, 1.7-3.8), and a protection by history of drug allergies (OR, 0.5; 95% CI, 0.2-0.9). These associations were not appreciably modified by allowance for major identified potential confounding factors and were observed for diseases occurring less than 5 or 5 or more years before liver cancer diagnosis, although for cirrhosis the risk was higher in the short term occurrences (OR, 50). For hepatitis, the association was more evident at older ages, confirming the long lead time between infection and cancer occurrence, while for diabetes it was stronger (or restricted) to cases aged less than 60, suggesting a possible specific role of type I diabetes. While for hepatitis, cirrhosis, and blood transfusion this study offers further quantitative estimates of risk in a European population, the possible direct association with diabetes and protection by drug allergy were unexpected, lacked plausible biological or previous epidemiological support, and should be simply regarded as working hypotheses for further work.