Improvements in surgical Results for lung cancer from 1989 to 1999 in Japan

Background: In 1986, Japanese Association for Thoracic Surgery started a nationwide survey of the number of primary lung cancer undergoing resection and this survey was continued annually. Thereafter, investigations of lung cancer surgical Results have been conducted three times. The postoperative overall 5-year survival rate was 47.8% in resected cases in 1989, 52.3% in 1994, and 62.0% in 1999, showing improvement over the decade (p < 0.01). Objective: To clarify the factors influencing survival improvements retrospectively. Patients and Methods: The subjects of the investigation are the patients who underwent resection for primary lung cancers in 1989, 1994, and 1999. Postoperatively, after 5 years, surveys of surgical Results were sent to institutes where lung cancer resection had been performed. The subjects undergoing resection who provided 10 items (age, sex, pathologic T factor, pathologic N factor, pathologic M factor, date of resection, histology, curability, prognosis, and survival time) numbered 3004 in 1989, 6895 in 1994, and 12,235 in 1999. They were classified according to the Union International Contre le Cancer 1997 revised tumor, node, and metastasis classification. Differences in age, gender, histology, pathologic stage, curability, and operative death rates were analyzed for each survey year. Results: According to the changes in proportions, the cases over 70 years of age, women, and pathologic stage I increased significantly (p < 0.001), whereas in cases with small cell lung cancer, incomplete resection and operative death decreased significantly over time (p < 0.001). Conclusion: The postoperative 5-year survival rate in Japan improved between 1989 and 1999. The main cause of this improvement was the increase in early stage lung cancer, especially cases with tumors 2 cm or less in size.