9. Cancer Information and Epidemiology Division

Epidemiological studies are currently underway to elucidate and evaluate risk and protective factors in the causation of cancer.^(110,111) Clinical epidemiological studies are also being conducted to investigate prognostic factors in the clinical course of cancer.^{(112,113,126)} Special efforts have been made in the study of familial cancer risk. Information infrastructures such as cancer registries, data coordination for multi-institutional collaborative clinical trials, and cancer center networks are under development for comprehensive data collection, analysis and dissemination of cancer information.
The National Cancer Center is designated by the World Health Organization as a WHO Collaborating Centre for Reference on Smoking and Health, and the Division takes the responsibility of running the Centre.

Epidemiological Studies of Etiologic and Preventive Factors of Cancer

The prevalence of Helicobacter pylori infection was examined in a sample of 1,207 patients in Tokyo University Hospital and the overall prevalence rate was found to be 39%. It is noteworthy that those born in the 1940s and 1950s showed a higher prevalence rate than others, suggesting the probability of a high incidence of gastric cancer in forthcoming years.
A series of epidemiological studies were conducted to investigate the cancer risk among patients with Minamata disease, who were exposed to methylmercury. In an exploratory study of 289 patients with Minamata disease, a non-significant increase in mortality from lymphoma and leukemia was observed.⁽¹¹⁰⁾ To confirm this finding, a larger scale historical cohort study of 1,351 patients was conducted and a statistically significant increase in leukemia deaths was observed.⁽¹¹¹⁾
A population-based prospective cohort study is underway in collaboration with the Epidemiology and Biostatistics Division and the National Cardiovascular Disease Center. A nutritional survey of sampled subjects is in progress to validate a food frequency questionnaire used for the entire study subject population.

Epidemiology of Familial Cancer

Studying familial cancer is an effective means of elucidating the role of genetic alterations in cancer development. However, identification of such families still relies on experienced physicians. To overcome this limitation, a computer software (Family Help) was developed, on which comprehensive family histories can be collected and maintained efficiently. A data set of hereditary nonpolyposis colorectal cancer (HNPCC) cases was analyzed using this system to evaluate various criteria for identification of HNPCC families from colorectal cancer cases.
The family histories of 3,548 gastric cancer patients treated in the National Cancer Center Hospital were analyzed in an attempt to investigate the familial risk of gastric cancer. The siblings of patients, who had developed gastric cancer by age 50, were found to have an increased risk of gastric cancer before age 50, but the parents did not show such an increased risk. Further analysis is currently underway.

Clinical Epidemiology of Cancer

Statistical analysis of cancer patients provides useful information for evaluating diagnostic and treatment methods. A survival analysis of 4,864 astrocytic tumor cases, who were registered in the Brain Tumor Registry of Japan, revealed that histology, age at diagnosis, clinical grade, tumor size, and tumor location were independent prognostic factors.⁽¹¹²⁾
A total of 386 patients who underwent complete resection of hepatocellular carcinoma were assessed retrospectively with regard to tumor recurrence. The presence of portal vein invasion and/or intrahepatic metastasis, underlying liver cirrhosis, and perioperative blood transfusion were identified as independent prognostic factors.⁽¹¹³⁾

JCOG Statistical Center

The Japan Clinical Oncology Group (JCOG) is a multi-institutional collaborative study group, and the Division currently manages the JCOG Statistical Center, taking the responsibilities for data management and statistical analysis. Currently, a total of 64 clinical trials are being managed by the center.

Cancer Informatics and Telemedicine

Ongoing research and development projects include methods of data collection, image processing, dissemination and exchange based on high performance supercomputers and a nationwide network. Internet-based application programs are developed for online cancer registration and case reporting to the JCOG Statistical Center. The algorithms for computer assisted diagnostic systems have been developed for thin section CT images, in which abnormal shadows are detected automatically for initial screening. A field trial of this system is in progress.

List of papers from this division

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