The mechanism of the enhanced transport efficiency in a vacuum arc plasma source equipped with a curved magnetic filter is investigated. The relationship between the transported ion current and the cathodic arc current is determined, and our results suggest that the outer and inner walls of the duct interact with the plasma independently. The plasma flux is composed of two components: a diffusion flux in the transverse direction due to particle collisions, and a drift flux due to the ion inertia. The inner wall of the magnetic duct sees only the diffusion flux while the outer wall receives both fluxes. Thus, applying a positive potential to the outer duct wall reflects the ions and increases the output current. Our experimental data also show that biasing both sides of the duct is more effective than biasing the outer wall alone.

In 1980, the ratio of home birth to public hospital perinatal and neonatal mortality rates decreased from Northern to Southern Italy, being inversely related to the proportion of home deliveries and probably reflecting the effect of planned versus unplanned home births. The post neonatal mortality rate in Southern Italy was about four times as high in children born at home (9.5/1,000 live births) than in those delivered in public hospitals (2.6/1,000 live births), probably reflecting differences in the socioeconomic status according to the birthplace selection in various regions.

Parazzini F {Istituto di Ricerche Farmacologiche ‘Mario Negri’ via Eritrea 62,20157 Milan, Italy), Hildesheim A, Ferraroni M, La Vecchia C and Brinton LA. Relative and attributable risk for cervical cancer: A comparative study in Italy and the United States. International Journal of Epidemiology 1990, 19: 539–545. The attributable risk for invasive cervical cancer in the US and Italian populations has been estimated in relation to main ‘aetiological’ factors (number of sexual partners, age at first intercourse, parity, oral contraceptive use and smoking) and history of Pap smear using data from two case-control studies conducted in the US (466 cases and 788 controls) and Italy (528 cases and 456 controls). The risk of cervical cancer increased in both studies with multiple sexual partners, decreasing age at first intercourse, higher parity, oral contraceptive use and smoking. Levels of exposure to various risk factors were markedly different in the two countries (ie number of sexual partners, frequency of oral contraceptive use and smoking were greater in the US). Multiple Pap smears and a short interval since last Pap smear strongly reduced risk of cervical cancer in both populations, although screening was much more widespread in the US study population, with only 9% of controls reporting no previous smear versus 38% of the Italian control series. The combined population attributable risk for the five ‘aetiological’ risk factors was slightly greater in the US study (76%) than in the Italian one (69%), chiefly because of a higher prevalence of exposure to sexual factors in US study women. A substantially larger proportion of Italian cases were due in part to deficiency in screening (46% in US and 84% in Italy). Thus, further inclusion of the effect of screening programmes (number of Pap smears and time since last Pap) led to an overall proportion of cases attributable to the examined risk factors of 87% in the US and 95% in Italy.

VECCHIA, CARLO LA; PARAZZINI, FABIO; DECARLI, ADRINO; FRANCESCHI, SILVIA; FASOLI, MONICA; FAVALLI, GIUSEPPE; NEGRI, EVA; PAMPALLONA, SANDRO Author Information

The relation between major indicators of sexual habits (age at first intercourse and total number of sexual partners), history of selected venereal diseases, and cervical neoplasia was investigated using data from a case-control study of 206 cases of cervical intraepithelial neoplasia compared with 206 age-matched outpatient controls, and of 327 cases of invasive cancer compared with 327 control subjects in hospital for acute conditions unrelated to any of the established or suspected risk factors for cervical cancer. The relative risks increased with decreasing age at first intercourse and increasing number of sexual partners both for intraepithelial and for invasive cancers. The effects of these two variables were independent, since they were only marginally affected by reciprocal adjustment, or by allowance for several other identified potential distorting factors. The negative association with age at first intercourse was particularly strong in the case of invasive cancers, with risk estimates over five-fold elevated for women reporting their first intercourse before age 18 compared with those aged over 22 years. This relation might be discussed in terms of multistage models of carcinogenesis, which predict that the incidence of epithelial carcinomas is a function of duration of exposure. In fact, when age was allowed for, the relative risks of cervical neoplasia were positively and strongly related with the total duration of the interval between age at diagnosis/interview and age at first intercourse. Clinical histories of several sexually transmitted diseases were positively associated with the risk of intraepithelial neoplasia. In particular, genital warts were reported by nine cases but no control subject. No such association, however, emerged for invasive carcinomas. Thus, the current findings confirm that, although intraepithelial neoplasia and invasive cervical cancer appear to share several important epidemiological features, the specific (infectious) agents implicated in dysplastic lesions probably differ to some extent from those causing invasive cancer.

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.

The relationship between methylxanthine (Mx) consumption and benign breast disease was evaluated in a case-control study of 288 women with histologically confirmed benign breast lumps (203 dysplastic lesions and 85 benign tumors) and 2 groups of control women--285 patients in the hospital for acute conditions apparently unrelated to the consumption of Mx-containing beverages and 291 outpatients. The relative risk estimates of dysplastic breast lesions (fibrocystic disease), with allowance for all identified potential distorting factors, for women who drank 1-2 or 3 or more cups of coffee per day were 4.1 and 6.4, respectively, when the hospital controls were the comparison group and 2.0 and 3.7, respectively, when the outpatient controls were the comparison group. The relationship was even stronger when the total consumption of Mx-containing beverages (coffee plus tea) was considered and increased with increasing duration of use. The association was not explained by any of the major risk factors for fibrocystic breast diseases or by differences in general characteristics or other lifestyle habits between cases and controls. Mx consumption was not related to the risk of benign breast tumors (fibroadenomas). These findings support the hypothesis that Mx consumption is related to the risk of dysplastic lesions of the breast.

Controversial topics in the epidemiology of cervical neoplasia are reviewed, in the light of data from studies conducted in Italy and indications from the literature. The downward trends registered over the last three decades in mortality from cervical cancer seem to be levelling off in the younger age groups (below age 45). This may be partly due to changes in sexual habits in younger women, but is certainly attributable to deficiencies in cervical screening. Pap smear, in fact, strongly reduces the risk of cervical neoplasia, the protection (as suggested by data from a case control study), being long lasting (over five years and perhaps around 10-15 years) for invasive cancers. The results of the same case-control study indicate that, although women with pre-invasive and invasive conditions seem to share several unspecific indicators of sexual habits (i.e., total number of partners and age at first intercourse), they appear to differ with regard to clinical history of specific venereal disease. In fact, genital warts, herpes genitalis and trichomoniasis were more frequent in cases of intraepithelial neoplasia, but not of invasive cancer. The implications of these findings, and of other controversial points in the epidemiology of cervical neoplasia, such as oral contraceptives, cigarette smoking and diet, are discussed with regard to indications from other disciplines (chiefly molecular hybridization and stochastic models of carcinogenesis).

The distribution of death certification rates from various cancers or groups of cancers in broad Italian geographical areas (north/centre/south) was analysed. In both sexes, total cancer mortality was considerably elevated in the north of the country compared to southern regions (around 70% for males and 30% for females in the truncated 35-64 rate), and generally intermediate in central areas. Northern mortality rates were higher for respiratory cancers and other tobacco related neoplasms (excluding bladder), with a north/south ratio ranging from 1.5 for lung and most respiratory sites to about 4.0 for oesophageal cancer in males. There was little tendency towards a leveling of these differences in younger (40-49 year old) males. Northern areas showed higher death certification rates for cancers of the stomach, large bowel, liver and most other digestive sites. The lower gastric cancer mortality registered in southern Italy is curious, since this is the poorest part of the country. Death certification rates from all other common neoplasms (uterus apart) were also elevated in the north. The geographical variation, however, appeared more limited for non-epithelial neoplasms. The substantial differences in cancer mortality between various Italian geographical areas can hardly be dismissed as due to lower death certification accuracy in the south. Some of the differences can be explained in terms of available knowledge of the causes of cancer (eg reproductive factors for breast and ovarian neoplasms, alcohol plus tobacco for oesophageal cancer). However, the lower mortality from respiratory cancers in southern areas can only with some difficulty be totally explained in terms of tobacco consumption. Likewise, the north/south variation cannot be related to non-specific consequences of industrialization, since cancer mortality was similarly elevated in highly industrialized and chiefly rural northern areas. It is conceivable that dietary factors may also explain some of the differences. However, at present, there is no obvious general explanation for this quite peculiar geographical distribution of cancer mortality within a single country.