Naoyuki Okamoto

Increased risk of lung cancer in Japanese smokers with class mu glutathione S-transferase gene deficiency

Japanese lung cancer patients (n = 121) and community controls (n = 201), both with current smoking history and aged < or = 69, were compared for the rates of class mu glutathione S-transferase (GSTmu) negative genotype detected by polymerase chain reaction. The prevalence of the GSTmu negative genotype was 45.3% in the community control group and 68.4%, 69.2%, 54.3% and 72.7% in the squamous cell carcinoma, small cell carcinoma, adenocarcinoma and other primary lung cancer groups, respectively. Odds ratios adjusted for age, sex composition and smoking index by multiple logistic regression analysis were 2.71 (1.23-5.99), 2.72 (1.11-6.66), 1.33 (0.68-2.60), and 3.27 (0.83-12.81), respectively. These results suggest that smokers with a GSTmu negative genotype are at higher risk for bronchial carcinoma than smokers with positive genotype.

Reproductive and menstrual factors and thyroid cancer among Japanese women: the Japan Collaborative Cohort Study.

AIM Thyroid cancer is more frequent in women than in men, suggesting the potential role of reproductive and menstrual factors in this cancer. To investigate the association with these factors, we examined 37,986 women involved in the Japan Collaborative Cohort (JACC) Study from 1988 to 1997. METHODS Reproductive and menstrual factors were assessed with a self-administered questionnaire at baseline. Hazard ratios (HR) and 95% confidence intervals (95% CI) of thyroid cancer incidence were estimated using Cox proportional hazards regression. RESULTS Eighty-six new cases of thyroid cancer were recorded during 379,281 person-years of follow-up. Overall incidence rate was 22.7 per 100,000 person-years, with a diagnosed peak of 38.2 per 100,000 at 55-59 years old. Multivariate HRs of 0.56 (95% CI 0.25-1.24) and 0.52 (95% CI 0.24-1.16) were observed for women who had experienced pregnancy or a live birth, respectively, but without statistical significance. Further, we saw no associations with other factors, such as age at menarche, age at menopause, age at first birth, or hormone use. CONCLUSIONS There was no significant association between thyroid cancer and reproductive and menstrual factors in the present study. Additional cohort studies should further examine this possible relationship among Japanese women.

A Comparative Epidemiologic Study on Geographic Distributions of Cancers of the Lung and the Large Intestine in Japan

To examine what kinds of factors could have caused the geographic variation observed in lung cancer morbidity in Japan, a correlation study was performed comparing various regional traits. The same study was also conducted on large intestinal cancer, aiming to distinguish the possible urban factors associated with both cancers. Lung cancer was highly correlated with industrialization‐related factors such as localization of manufacturing industries, automobile traffic and air pollution, whereas colon cancer was correlated with the population density of workers in the tertiary industries such as services, trade and government. A multiple regression analysis could not detect any single factor with an exceptionally strong influence on either cancer. The present findings suggest that the hazardous environmental condition of urban areas has, to some extent, contributed to the recent increase of lung cancer cases in this country.

Prospective study of transfusion history and thyroid cancer incidence among females in Japan

A link between hepatitis C virus (HCV) infection and thyroid cancer was recently reported in a series of case‐control studies in southern Italy. A prospective study could reinforce these findings. However, cohort studies that began before 1990 rarely assessed serological HCV infection. In addition, thyroid cancer is rare and generally has a good prognosis. Therefore, incidence outcome data are required, rather than mortality data, to evaluate the risk of thyroid cancer. Blood transfusion history might be a possible substitute measure to evaluate the cancer risks associated with HCV infection because blood transfusions were the major HCV transmission route in Japan until 1992. The purpose of our study was therefore to examine the association between transfusion history and thyroid cancer. A baseline survey of members of the JACC Study was conducted from 1988 until 1990, which involved 110,792 participants from 45 areas throughout Japan. Data were collected from a total of 37,983 women with no history of cancer at the baseline (337,906 person‐years) and 79 cases of thyroid cancer were identified among this group. A history of blood transfusion marginally increased the risk of thyroid cancer [risk ratio (RR) = 1.77, 95% confidence interval (CI) = 0.95–3.30], and a history of transfusion and/or liver disease significantly increased the thyroid cancer risk (RR = 1.84, 95% CI = 1.07–3.16). These results indirectly support an association between HCV and thyroid cancer. In addition, our data reveal an association between blood transfusion and thyroid cancer, which might be facilitated by transfusion‐associated immunomodulation.

Breast Cancer Clustering in Kanagawa, Japan: A Geographic Analysis

BACKGROUND The purpose of the present study was to determine geographic clustering of breast cancer incidence in Kanagawa Prefecture, using cancer registry data. The study also aimed at examining the association between socio-economic factors and any identified cluster. MATERIALS AND METHODS Incidence data were collected for women who were first diagnosed with breast cancer during the period from January to December 2006 in Kanagawa. The data consisted of 2,326 incidence cases extracted from the total of 34,323 Kanagawa Cancer Registration data issued in 2011. To adjust for differences in age distribution, the standardized mortality ratio (SMR) and the standardized incidence ratio (SIR) of breast cancer were calculated for each of 56 municipalities (e.g., city, special ward, town, and village) in Kanagawa by an indirect method using Kanagawa female population data. Spatial scan statistics were used to detect any area of elevated risk as a cluster for breast cancer deaths and/ or incidences. The Student t-test was performed to examine differences in socio-economic variables, viz, persons per household, total fertility rate, age at first marriage for women, and marriage rate, between cluster and other regions. RESULTS There was a statistically significant cluster of breast cancer incidence (p=0.001) composed of 11 municipalities in southeastern area of Kanagawa Prefecture, whose SIR was 35 percent higher than that of the remainder of Kanagawa Prefecture. In this cluster, average value of age at first-marriage for women was significantly higher than in the rest of Kanagawa (p=0.017). No statistically significant clusters of breast cancer deaths were detected (p=0.53). CONCLUSIONS There was a statistically significant cluster of high breast cancer incidence in southeastern area of Kanagawa Prefecture. It was suggested that the cluster region was related to the tendency to marry later. This study methodology will be helpful in the analysis of geographical disparities in cancer deaths and incidence.