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Akira Masaoka, an honorary member of the Japanese Association for Thoracic Surgery, died on November 2, 2014, at the age of 84 years. He was lonely because his wife had died 5 months earlier.

Dr. Masaoka was born in Osaka in 1930. After graduating from the Osaka University Medical School in 1954, he started surgical training at the 1st Department of Surgery, Osaka University Medical School. In 1978, he became an associate professor in that department, and in 1980, a professor in the 2nd Department of Surgery, Medical School, Nagoya City University.

He held a number of important positions including director of the Nagoya City University Hospital. He retired from the Nagoya City University in 1996, and became a professor emeritus. Thereafter he was the director of the Kenporen Osaka Central Hospital.

Dr. Masaoka’s medical research and surgical career were spent at Osaka University and Nagoya City University. When I started training in thoracic surgery at the 1st Department of Surgery, Osaka University Medical School, three excellent thoracic surgeons, fortunately, were in the department: Dr. Hisao Manabe, the head of the 1st Department of Surgery; Dr. Yasunaru Kawashima, the leader of cardiac surgeons; and Dr. Akira Masaoka, the leader of general thoracic surgeons. Dr. Masaoka and Dr. Kawashima had been classmates at Naniwa High School.

Dr. Masaoka was interested in all areas of thoracic surgery, especially in the study of thymic tumor. After basic training in thoracic surgery, I started clinical research on thymoma and other mediastinal tumors under the lead of Dr. Masaoka. The effectiveness for myasthenia gravis (MG) of the resection of the thymus or thymoma was reported sporadically, but at that time, the evaluation of this surgery for MG had not been firmly established.

Dr. Masaoka made it clear that the thymic tissue is distributed in a wide range of the anterior mediastinum, and he proposed the extended thymothymectomy against MG. This new surgical method featured the total resection of thymoma, the massive thymus, and thymic tissues in the anterior mediastinum. The extended thymothymectomy for MG showed higher effectiveness for MG than other surgical procedures. Now Dr. Masaoka’s extended thymothymectomy is a standard type of surgery in MG treatment.

From the idea that all thymomas have malignant potential and advance gradually, he proposed a clinical staging of thymoma consisting of five stages, namely, stage I, stage II, stage III, stage IVa and IVb. This clinical staging of thymoma by Dr. Masaoka expressed the prognosis of the disease and has been used in other parts of the world as “Masaoka’s classification”. In recent years, tumor status, nodes status and metastasis status (TNM) classification of epithelial thymic tumors (including thymic carcinoid and thymus cancer) has been proposed by WHO. The clinical staging of thymoma based on the TNM classification is almost the same as Masaoka’s classification.

Criteria of Clinical Stages by A. Masaoka

  • Stage I: Macroscopically completely encapsulated and microscopically no capsular invasion

  • Stage II: 1. Macroscopic invasion into surrounding fatty tissue or mediastinal pleura, or 2. Microscopic invasion into capsule

  • Stage III: Macroscopic invasion into neighboring organ i.e. pericardium, great vessels, or lung

  • Stage IVa: Pleural or pericardial dissemination

  • Stage IVb: Lymphogenous or hematogenous metastasis

Dr. Masaoka presented the invited special lecture in 1989 at Bethesda, MD, at the 1st International Conference on Thymic Malignancies, which was held in the United States. Later, the name of the Conference was changed to the International Thymic Malignancy Interest Group (ITMIG). He was awarded a lifetime honorary membership in ITMIG in 2009, and ITMIG has introduced the Masaoka Award (Masaoka Prize) in his honor. Dr. Masaoka served as president of many Japanese medical societies, including the Japanese Association for Chest Surgery, the Japan Lung Cancer Society, and the Japan Society for Bronchology, among others.

He was not only an excellent thoracic surgeon but also an excellent musician, being a talented pianist, conductor, and composer. He composed two study collections and three operas, namely, “Shingen”, “Sokoku”, and “Zeami”. He held concerts of his own study collections two times and of his own operas three times. In opera, he led the orchestra and was met by loud applause from the audiences at his performances.

Dr. Masaoka was a great teacher to me.