Tomotaka Sobue

Cancer Incidence and Incidence Rates in Japan in 2004: Based on Data from 14 Population-based Cancer Registries in the Monitoring of Cancer Incidence in Japan (MCIJ) Project

The Japan Cancer Surveillance Research Group aimed to estimate the cancer incidence in Japan in 2008 based on data collected from 25 of 34 population-based cancer registries, as part of the Monitoring of Cancer Incidence in Japan project. The incidence in Japan for 2008 was estimated to be 749 767 (C00-C96). Stomach cancer and breast cancer were the leading types of cancer in males and females, respectively.

Lung cancer occurrence in never-smokers: an analysis of 13 cohorts and 22 cancer registry studies.

Background Better information on lung cancer occurrence in lifelong nonsmokers is needed to understand gender and racial disparities and to examine how factors other than active smoking influence risk in different time periods and geographic regions. Methods and Findings We pooled information on lung cancer incidence and/or death rates among self-reported never-smokers from 13 large cohort studies, representing over 630,000 and 1.8 million persons for incidence and mortality, respectively. We also abstracted population-based data for women from 22 cancer registries and ten countries in time periods and geographic regions where few women smoked. Our main findings were: (1) Men had higher death rates from lung cancer than women in all age and racial groups studied; (2) male and female incidence rates were similar when standardized across all ages 40+ y, albeit with some variation by age; (3) African Americans and Asians living in Korea and Japan (but not in the US) had higher death rates from lung cancer than individuals of European descent; (4) no temporal trends were seen when comparing incidence and death rates among US women age 40–69 y during the 1930s to contemporary populations where few women smoke, or in temporal comparisons of never-smokers in two large American Cancer Society cohorts from 1959 to 2004; and (5) lung cancer incidence rates were higher and more variable among women in East Asia than in other geographic areas with low female smoking. Conclusions These comprehensive analyses support claims that the death rate from lung cancer among never-smokers is higher in men than in women, and in African Americans and Asians residing in Asia than in individuals of European descent, but contradict assertions that risk is increasing or that women have a higher incidence rate than men. Further research is needed on the high and variable lung cancer rates among women in Pacific Rim countries.

The Japanese Guidelines for Gastric Cancer Screening

BACKGROUND Gastric cancer is the leading cause of death from cancer in Japan. In 2004, there were 50 562 deaths from gastric cancer; they accounted for 15.8% of the total number of cancer deaths. Since 1983, under the Health Service Law for the Aged, gastric cancer screening has been conducted nationwide for all residents aged 40 years and over. METHODS On the basis of the standardized method developed for the Japanese Guidelines for Cancer Screening, the efficacies of various methods for gastric cancer screening were evaluated and the guideline was developed. RESULTS Four methods for gastric cancer screening were evaluated: photofluorography, endoscopy, serum pepsinogen testing and Helicobacter pylori antibody testing. On the basis of the analytic framework involving key questions, 1715 articles, published from January 1985 to February 2005, were selected using MEDLINE, the Japanese Medical Research Database and other methods. After the systematic literature review, 10 articles were identified as direct evidence and 49 articles as indirect evidence. The studies that evaluated mortality reduction from gastric cancer included five case-control and two cohort studies for radiographic screening. On the basis of the balance of benefits and harms, the recommendations for population-based and opportunistic screening were formulated. Gastric cancer screening using photofluorography was recommended for both screening programs. The other methods were not recommended for population-based screening due to insufficient evidence. CONCLUSIONS The guideline for gastric cancer screening guideline was developed based on the previously established method. Gastric cancer screening using photofluorography is recommended for population-based and opportunistic screening in Japan.

Cancer incidence and incidence rates in Japan in 2002: based on data from 11 population-based cancer registries.

The number of cancer incidences, crude incidence rates, age-standardized incidence rates in 2002 in Japan are estimated. The estimated total number of incidences was 570,598.

What has made the population of Japan healthy

People in Japan have the longest life expectancy at birth in the world. Here, we compile the best available evidence about population health in Japan to investigate what has made the Japanese people healthy in the past 50 years. The Japanese population achieved longevity in a fairly short time through a rapid reduction in mortality rates for communicable diseases from the 1950s to the early 1960s, followed by a large reduction in stroke mortality rates. Japan had moderate mortality rates for non-communicable diseases, with the exception of stroke, in the 1950s. The improvement in population health continued after the mid-1960s through the implementation of primary and secondary preventive community public health measures for adult mortality from non-communicable diseases and an increased use of advanced medical technologies through the universal insurance scheme. Reduction in health inequalities with improved average population health was partly attributable to equal educational opportunities and financial access to care. With the achievement of success during the health transition since World War 2, Japan now needs to tackle major health challenges that are emanating from a rapidly ageing population, causes that are not amenable to health technologies, and the effects of increasing social disparities to sustain the improvement in population health.

Randomized trial of dietary fiber and Lactobacillus casei administration for prevention of colorectal tumors

The epidemiologic evidence that dietary fiber protects against colorectal cancer is equivocal. No large‐scale clinical study of the administration of Lactobacillus casei has been reported. We examined whether dietary fiber and L. casei prevented the occurrence of colorectal tumors. Subjects were 398 men and women presently free from tumor who had had at least 2 colorectal tumors removed. Subjects were randomly assigned to 4 groups administered wheat bran, L. casei, both or neither. The primary end point was the presence or absence of new colorectal tumor(s) diagnosed by colonoscopy after 2 and 4 years. Among 380 subjects who completed the study, 95, 96, 96 and 93 were assigned to the wheat bran, L. casei, both and no treatment groups, respectively. Multivariate adjusted ORs for occurrence of tumors were 1.31 (95% CI 0.87–1.98) in the wheat bran group and 0.76 (0.50–1.15) in the L. casei group compared to the control group. There was a significantly higher number of large tumors after 4 years in the wheat bran group. The occurrence rate of tumors with a grade of moderate atypia or higher was significantly lower in the group administered L. casei. No significant difference in the development of new colorectal tumors was observed with administration of either wheat bran or L. casei. However, our results suggest that L. casei prevented atypia of colorectal tumors.

Survival for clinical stage I lung cancer not surgically treated. Comparison between screen-detected and symptom-detected cases

To assess the extent of overdiagnosis bias in lung cancer screening, clinical Stage I lung cancer cases detected by chest radiograph examination, with histologic or cytologic evidence of malignancy and not treated by surgical operation, were followed up for more than 10 years. Of 1297 screen‐detected and 1297 symptom‐detected cases collected from 20 institutions, 42 screen‐detected and 27 symptom‐detected cases satisfied the study criteria. In about half of the cases, the patients had no contraindication for surgical treatment, but they refused surgical procedure. All such patients from the screen‐detected and symptom‐detected groups died within 122 and 67 months, respectively, of diagnosis. Among the screen‐detected and symptom‐detected cases, 80% and 81%, respectively, of the patients died of lung cancer. The median survival time was 25 and 13 months for those in the screen‐detected and symptom‐detected groups, respectively. The difference in survival was statistically significant between the two groups, which indicated the effect of lead time and length‐biased sampling. Analysis of the causes of death other than lung cancer showed that there was no difference in the observed cumulative rates of deaths of other causes between the two groups, and these figures were almost the same as those expected from the general population. This indicates that overdiagnosis bias would be minimal in screen‐detected lung cancer cases detected by chest radiograph examination.

Cigarette smoking and subsequent risk of lung cancer by histologic type in middle‐aged Japanese men and women: The JPHC study

In order to update the findings of relative risk associated with cigarette smoking for lung cancer by histologic type in Japan, the data from a population‐based cohort study of 91,738 men and women were analyzed. During 1990–1999, 422 lung cancer incident cases were identified. The relative risk for all incident cases associated with current smokers versus non‐smokers was 4.5 [95% confidence interval (CI): 3.0–6.8] and 4.2 (95% CI: 2.4–7.2), for men and women, respectively. When divided by histologic type, relative risk for squamous cell carcinoma and small cell carcinoma was 12.7 (95% CI: 4.7–34.7) and 17.5 (95% CI: 4.9–62.1), while for adenocarcinoma it was 2.8 (95% CI: 1.6–4.9) and 2.0 (95% CI: 0.8–5.0) for men and women, respectively. We confirmed that the lung cancer risk in men rose with increasing cigarette smoking, especially the duration of smoking among current smokers and decreased after the cessation of smoking among former smokers. Unlike the US or European countries, the relative risk did not increase in this updated study, compared with previous studies in 1960s to 1990s in Japan either for all incident cases or for specific histologic types and the magnitude of relative risks was substantially lower than that observed in the US or European countries, especially for adenocarcinoma.

Association of amino acid substitution polymorphisms in DNA repair genes TP53, POLI, REV1 and LIG4 with lung cancer risk.

Single nucleotide polymorphisms (SNPs) were searched for in 36 genes involved in diverse DNA repair pathways, and 50 nonsynonymous (associated with amino acid changes) SNPs identified were assessed for associations with lung cancer risk by a case‐control study consisting of 752 adenocarcinoma cases, 250 squamous cell carcinoma cases and 685 controls. An SNP, Arg72Pro, of the TP53 gene encoding a DNA damage response protein showed the strongest association with squamous cell carcinoma risk (OR Pro/Pro vs. Arg/Arg = 2.2), while 2 other SNPs, Phe257Ser of the REV gene encoding a translesion DNA polymerase and Ile658Val of the LIG4 gene encoding a DNA double‐strand break repair protein, also showed associations (OR Ser/Ser vs. Phe/Phe = 2.0 and OR Ile/Val vs. Ile/Ile = 0.4, respectively). An SNP, Thr706Ala, in the POLI gene encoding another translesion DNA polymerase was associated with adenocarcinoma and squamous cell carcinoma risk, particularly in individuals of ages < 61 years (OR Ala/Ala + Ala/Thr vs. Thr/Thr = 1.5 and 2.4, respectively). POLI is the human counterpart of PolI, a strong candidate for the Par2 (pulmonary adenoma resistance 2) gene responsible for adenoma/adenocarcinoma susceptibility in mice. The present results suggest that these 4 SNPs function as genetic factors underlying lung cancer susceptibility by modulating activities to maintain the genome integrity of each individual.

Population Attributable Fraction of Mortality Associated with Tobacco Smoking in Japan: A Pooled Analysis of Three Large-scale Cohort Studies

Background Quantitative measures of the burden of tobacco smoking in Asian countries are limited. We estimated the population attributable fraction (PAF) of mortality associated with smoking in Japan, using pooled data from three large-scale cohort studies. Methods In total, 296,836 participants (140,026 males and 156,810 females) aged 40-79 years underwent baseline surveys during the 1980s and early 1990s. The average follow-up period was 9.6 years. PAFs for all-cause mortality and individual tobacco-related diseases were estimated from smoking prevalence and relative risks. Results The prevalence of current and former smokers was 54.4% and 25.1% for males, and 8.1% and 2.4% for females. The PAF of all-cause mortality was 27.8% [95% confidence interval (CI): 25.2-30.4] for males and 6.7% (95% CI: 5.9-7.5) for females. The PAF of all-cause mortality calculated by summing the disease-specific PAFs was 19.1% (95% CI: 16.0-22.2) for males and 3.6% (95% CI: 3.0-4.2) for females. The estimated number of deaths attributable to smoking in Japan in 2005 was 163,000 for males and 33,000 for females based on the former set of PAFs, and 112,000 for males and 19,000 for females based on the latter set. The leading causes of smoking-attributable deaths were cancer (61% for males and 31% for females), ischemic heart diseases and stroke (23% for males and 51% for females), and chronic obstructive pulmonary diseases and pneumonia (11% for males and 13% for females). Conclusion The health burden due to smoking remains heavy among Japanese males. Considering the high prevalence of male current smokers and increasing prevalence of young female current smokers, effective tobacco controls and quantitative assessments of the health burden of smoking need to be continuously implemented in Japan.