Patients with hepatitis C virus infection have a greatly increased risk of liver cancer. Further studies are required to clarify the roles of other risk factors, including drinking and smoking habits.

In order to evaluate the effectiveness of a mass screening program for stomach cancer, a case-control study was conducted in Nose town in Osaka, Japan. The case series consisted of all deaths from stomach cancer during the period 1969-1981 (54 in males and 37 in females). For each case, 3 controls of the same sex and from the same precinct as the case, and born within 5 years of the case birth-year, were selected at random from Nose town residents alive at the date of death of the relevant case. We then investigated whether each case and corresponding controls had ever had screening tests before the date of diagnosis of the case. From the matched analysis of the distribution of screening in case-control combination, the odds ratio of screened vs. unscreened among those who died from stomach cancer compared to those who did not was calculated as 0.595 (90% confidence interval: 0.338-1.045) among males and 0.382 (0.185-0.785) among females. When the screening tests conducted within 12 months of diagnosis were ignored on the presumption that they were symptom-related, the odds ratio was calculated as 0.519 (0.297-0.905) among males and 0.486 (0.239-0.986) among females. These data strongly suggest that the mass screening program is effective in reducing stomach cancer mortality.

This study was conducted to examine the incidence rates and cumulative risks of second primary cancers in Osaka and to compare the observed number of second primary cancers with the expected number calculated using cancer incidence rates among Osaka residents. Study subjects were all reported cases aged 0–79 who were first diagnosed as having a first primary cancer between 1966–86. Incidence of second primary cancer among the study subjects was examined through to the end of 1989. The total number of study subjects was 217,307. During the follow‐up period (mean duration: 3.7 years), second primary cancers developed in 5,071 patients (2.3%). Incidence of synchronous (interval <3 months) and metachronous (interval ≥ 3 months) second primary cancers increased in the later years. Incidence rates of second primary cancers were significantly associated with gender (male), age and calendar year at diagnosis of the first cancer. Based on the incidence rates, cumulative risk of developing metachronous second primary cancer was calculated. The ten‐year cumulative risk was estimated as 10% for those who developed their first cancer during their sixties in 1978–83. The observed number of second primary cancers (including synchronous) was compared with the expected number. The ratios of observed‐to‐expected numbers were generally lower than 1.0 among those who developed their first cancer in 1966–77, while these ratios were higher than 1.0 among those who developed their first cancer in 1978–86. The ratios were much higher than 1.0 among those who developed their first cancer in their childhood and youth. Patients who had developed cancer of the colon, larynx, lung, bladder, or breast (female) showed significantly higher risk of developing second primary cancer during the period 1–4 years after diagnosis of the first cancer.

A case-control study was undertaken to evaluate the roles of hepatitis B virus (HBV), blood transfusion, alcohol drinking and cigarette smoking in the etiology of hepatocellular carcinoma (HCC) in Osaka, Japan. A total of 229 cases and 266 hospital controls were included in our study. The relative risks of HCC obtained after adjustment for age, sex and other important variables were 14.3 (95% confidence interval (CI): 5.7-36.3) for HBsAg positives, 4.3 (95% CI: 1.9-9.6) for blood recipients and 3.2 (95% CI: 2.0-5.1) for heavy drinkers. A statistically significant dose-response relationship was observed between the risk of HCC and total alcohol consumption. The overall risk for HCC was also significantly elevated among smokers; however, there was no consistent dose-response relationship between the risk and cigarette consumption. We conclude that HBV, blood transfusion and excessive alcohol drinking play important roles in the etiology of HCC in Osaka, Japan. Further investigation is needed to clarify the possible etiological role of smoking.

In order to confirm the close association between chronic hepatitis B virus (HBV) infection and primary hepatocellular carcinoma (PHC) in Japan, 8,646 male hepatitis B surface antigen (HBs Ag)-positive blood donors (GPT less than or equal to 35 Karmen units) were followed up. Twenty liver cancer cases were observed during the follow-up period (average 6.2 years), the expected number calculated on the basis of age-specific incidence rates among the general population being 3.03. Therefore, the observed to expected ratio of liver cancer was 6.60, that is significantly higher than 1.0. During the same follow-up period, a total of 76 deaths were observed, of which 20 were due to liver cancers and 9 to liver cirrhoses, meaning that nearly 40% of deaths among the study subjects due to chronic liver diseases. Drinking and smoking habits in the liver cancer cases were compared with those observed in healthy male HBV carriers. A strong positive association between drinking habits and liver cancer was observed and there was a significant dose-response relationship after adjustment for cigarette smoking habits. A high risk of liver cancer was also observed among heavy smokers, but a significant dose-response relationship could not be found between smoking habits and liver cancer, partly because of the limited number of the study subjects. These findings suggest that HBV is a major etiologic agent of PHC in Japan where the HBs Ag prevalence rate is about 2%, and alcohol drinking and cigarette smoking may promote the process of HB viral hepato-carcinogenesis.