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TAJIMA Kazuo, Director, Aichi Cancer Center Research Institute

Kazuo TAJIMA, Director, Aichi Cancer Center Research Institute has studied relationships between cancer and lifestyles, researching ways to prevent cancer. As a young medical student, Dr. Tajima aimed to contribute to community health-care. Later, involved in epidemiology and viral archaeology in encounters with world researchers, he serendipitously found clues to the origins of mankind. He credits his curiosity and the encounters with making him who he is today.


Born in Hiroshima City in 1947, Dr. Tajima graduated from the Department of Orthopedics, School of Medicine, Osaka University in 1972. He then served as a doctor-in-training in the Surgery Department, Seirei Mikatahara General Hospital, Hamamatsu City, and later as a resident at the Pathological Department, Aichi Cancer Center Hospital. Following these, he became a researcher at the Division of Epidemiology and Prevention of the same cancer center. In 1986, he completed a master's course in the School of Public Health at Johns Hopkins University in the USA. After returning Japan, he served as Manager and Vice director at the Aichi Cancer Center. In 2006, he became Director of the Center, a position he continues to hold. Dr. Tajima is also Professor Emeritus at the Third Military Medical University and Huaxi School of Public Health, Sichuan University, China.

A sick child aiming to find his career in medicine

He was so sickly as a child that his family doctor told his parents he might not survive. However, he survived and later he became healthy enough to enjoy playing soccer at high school. Careful of his health, he enrolled in the Faculty of Medicine, Osaka University, and joined the Southeast Asia Medical Research Institute as well. Together with university doctors and nurses, he surveyed people's lifestyles on remote islands in Okinawa and rural areas in Borneo.

Working 24-hour shifts as a surgeon


In those days, many peasant farmers suffered from low back pain and  many keypunch operators in cities suffered from carpal tunnel syndrome. Following training for an orthopedic surgeon, he served as a surgeon at Seirei Mikatahara General Hospital in Hamamatsu City.
Staying at the hospital dormitory, whenever he got called out, even in the middle of the night, he engaged in surgery of the chest and digestive organs, gaining experience in the hospital. Interested in controlling pain, he went to Tokyo on weekends to study anesthesia induced by acupuncture.

Fascinated by pathology, he came face to face with ATL (Adult T-cell Leukemia)

At the hospital, four experienced outside doctors conducted pathological diagnosis on rotation. He even had the experience of taking dictation on findings delivered in German from one of the pathologists who was making observations through a microscope.

Impressed, Dr. Tajima bought a microscope with his first bonus. He wanted to study pathology further and applied for pathological diagnosis courses at the Aichi Cancer Center. As a student of pathology, he observed formalin-fixed surgical specimens of ATL which later would become an important area of research for him. Many ATL patients were in Kyushu. TOMINAGA Suketami, a manager of the Epidemiology Department and graduate from Osaka University, invited Dr. Tajima to join him in Kyushu as a resercher.

Survey on epidemic on Goto Islands

Dr. Tajima started to conduct research into cancer of the digestive tract and a culprit in causing ATL. Research into ATL initiated by Japanese made a great progress, identifying a virus causing ATL, HTLV-1 (human T-cell leukemia virus type I). Dr. Tajima investigated a viral epidemic on Goto Islands and found that people infected with the HTLV-1 virus came from the same family and that there were major transmission routes for HTLV-1: mother to child, husband to wife. It was a great medical achievement, making possible preventive measures that could be implemented within 10 years. It was also discovered that more HTLV-1 infection cases were found in secluded areas than in cities.

After diplomatic relation between Japan and China were normalized, Aichi Prefecture signed a friendship treaty with Jiangsu Province, resulting in Dr. Tajima being dispatched to the Cancer Hospital in Jiangsu Province in 1982 in an academic exchange on cancer research. An analysis of Chinese blood revealed that there were no persons infected with HTLV-1 in mainland China.

Studying the prevalence of HTLV-I infection in the world

In order to understand the prevalence of HTLV-I infection in the world, he started blood investigation in Indonesia and found there were no HTLV-I infection cases in any countries except for Japan. In 1988, at the HTLV-1-associated myelopathy (HAM) Conference in Kagoshima sponsored by WHO, a Colombian researcher told him that there were patients with conditions similar to those of HAM in Colombia.
Soon Dr. Tajima and his co-researcher, Dr. Shunro SONODA, Kagoshima University, went to Columbia to do surveys and identified that there were people in the Andes infected with HTLV-1 similar to that of the Japanese.
Later, they conducted a large-scale blood survey of residents living along the coast of the Caribbean Sea, in the Amazon rain forest, and remote areas in Patagonia and found that HTLV-1 infections were limited to the Andes.
Furthermore, they extracted provirus DNA from the bone marrow of Andean mummies. Their base sequences were similar to those of Ainu. They thus clarified the common origin of HTLV-1 in Asia and the Andes, suggesting the possibility that Mongoloids, the racial category of Japanese, migrated as far as the southern Andes.

Providing the world with blood collection

Collections of blood samples from indigenous people in the world are kept at Riken's BioResource Center in Tsukuba City as the "Sonoda-Tajima Collection." They are valuable genetic level materials for world researchers to study how humans spread from Africa. "Serendipitously, ATL research was helpful for other valuable research," Dr. Tajima says proudly.
He wanted to further study epidemiology. In 1985, funded by financial aid from the International Agency for Research on Cancer, he enrolled in the master's course at Johns Hopkins University's School of Public Health where epidemiology research was being conducted. During that year, he noticed that 80 percent of new patients visiting the Aichi Cancer Center were not cancer patients. After he returned to Japan, he started large-scale epidemiological research to compare lifestyles of cancer patients and those of non-cancer patients.
He collected data of almost ten thousand patients every year and posted research results on world medical journals; however, these achievements were not recognized. Then, Dr. Tajima epidemiologically showed that the lifestyles of randomly chosen 2000 general citizens in Nagoya City differed little from those of non-cancer patients. Since then, achievements of Hospital-based Epidemiologic Research Program at Aichi Cancer Center (HERPACC) have been recognized in the world.

Aiming to become a doctor as his mother wished him

Dr. Tajima would like to see young medical students become doctors and researchers investigating the origins of different diseases. He laments the fact that the number of medical students aiming to be researchers is decreasing. Dr. Tajima said, "When I turn 70, I want to get involved in community healthcare, my dream since I was young." He continues on his path as a doctor which was what his mother had hoped he would be.

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