Thoracic Surgery Division

Introduction
The Thoracic Surgery Division deals with various kinds of neoplasms and allied diseases sin the thorax, with the exception of the esophagus. Included are both primary and metastatic lung tumors, mediastinal tumors, pleural tumors (mesothelioma), and chest wall tumors. The surgical management of lung cancer patients has been the main clinical activity of the division, as well as the subject of most of its research. In addition to continuing to improve the procedures, such as the combined resection of neighboring vital structures and minimally invasive techniques (video-assisted thoracic surgery, VATS), it has become increasingly important to define the role of surgery in the multimodality treatment for patients with poor prognosis.

Routine Activities
The division has four attending surgeons. Three subteams with attending surgeons and residents provide all the inpatient care, operations, examinations, and outpatient care. For the chief resident, the first year of the two-year fellowship program is devoted to patient care, and the second year is devoted to clinical/basic research. We annually adopt two to three residents who want to major in general thoracic surgery. Beside two weekly division meetings for preoperative evaluation and inpatient review, the chest group has a plenary meeting to share basic information about the diagnosis and treatment of patients, especially those needing a multimodality approach.
The treatment strategy for patients with lung cancer is based on tumor histology (non-small cell vs. small cell), extent of disease (stage), and physical status of the patients. In lung cancer patients, surgical resection is usually indicated for stages I, II, and part of IIIA of non-small cell histology and stages I and II of small cell histology. However, to improve the poor prognosis of patients with clinically and histologically proven mediastinal lymph node metastasis or with invasion to the neighboring vital structures, the optimal treatment modalities are being sought in clinical trial setting.
Salvage and palliative resections are also important aspects of lung cancer surgery. Salvage surgery is intended to eradicate all the remaining or recurrent tumors when other modalities fail. Palliative resection is intended to treat jeopardizing symptoms such as intolerable pain or to avoid impending death caused by airway bleeding or other life-threatening situations.
For metastatic lung tumors, resection has been attempted on the basis of Thomfold s criteria; eligible patients are those who are at good risk, with no extrathoracic disease, with the primary site in control, and with completely resectable lung disease. Metastasis from the colorectal carcinoma is the most common cause in this category. For mediastinal tumors, thymic epithelial tumors are most commonly encountered lesion requiring surgical resection. In the mediastinum, where a variety of tumor histologies can arise, the treatment must be carefully determined by the cytologic/histologic diagnosis before surgery. For this purpose, a CT-guided needle biopsy is replacing the formerly common biopsy under X-ray fluoroscopy.

Research Activities
Owing to the advent of new technology in CT scanning, minute lung cancers are being found in a screening setting and by chance. They usually present as ground-glass opacity (GGO) appearance on CT, and their pathology is early adenocarcinoma termed as bronchioloalveolar carcinoma (BAC) . The surgical management of such GGO-BAC type of lung cancer remains undetermined in terms of extent of pulmonary parenchymal resection and lymph node dissection. Some cases might be followed up with careful watching by CT, since the existence of indolent tumors is known. We are currently still seeking for the most appropriate way of management of these patients.
The lymph node dissection for lung cancer has been one of the major issues in lung cancer, which has been extensively studied in our division. We continue to improve the surgical technique of dissection based on the oncological and surgical considerations: the most effective and least invasive lymph node dissection termed as selective mediastinal / hilar dissection according to the location of primary tumor by the lobe.
The video-assisted surgery for thoracic malig-nancies is also an important challenge of our division. Especially the indication and surgical technique of video-assisted surgery for early lung cancer are the points of great interest because of increased incidence of detection of minute tumors by improved CT devices and CT screening.
In this year, there were two important publications regarding the staging of lung cancer in our division. One article by Dr. Okumura dealt with the prognostic significance of the satellite nodule (metastasis) in the same lobe of the primary tumor, since the revised TNM system denoted the tumors with satellite nodule as T4 with little evidence of its prognosis. This study demonstrated that tumors with satellite nodule had, as described in TNM system, an equivalent prognosis to those with other denominator as T4. Another important issue is the prognostic significance of tumor size, especially size more than 10cm in diameter. Dr. Carbone, a visiting surgeon from Italy, found that tumors more than 10 cm in diameter could be upgraded to T3 category from T2. These two articles seem to have an impact on the current lung cancer staging.

Clinical Trials
The survival benefit of preoperative and postoperative chemotherapy for stage IIIA disease was evaluated in three JCOG studies (JCOG 92-09-055, JCOG 93-04-059, JCOG 9805). Although JCOG-9805 was conducted to evaluate the feasibility of surgical resection after concurrent chemoradiotherapy in a phase II setting, this multiinstitutional study was terminated because of the higher mortality rate experienced in some institutions participated in the study. Our group has chosen to continue this study in collaboration with the thoracic oncology group, and we continue to accrue the candidates. A similar preoperative approach with concurrent chemoradiotherapy has been employed for a special type of lung cancer known as superior sulcus tumor (STS, JCOG 9806). In our division, we have experienced neither fatal toxicity nor serious surgical complication as a result of this approach.

H. ASAMURA

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