Abstract
Background : Although sputum cytology is the only way to detect early hilar lung cancer in lung cancer screening, there are also various problems. Therefore, the subcommittees concerning sputum cytology was established in each the Japan Lung Cancer Society and the Japanese Society of Clinical Cytology, and in a joint effort with the Japan Society for Respiratory Endoscopy, the investigation of these problems were reported by the committee of the three societies.
We concluded that confirming the usefulness of sputum cytology at present is the inevitable and the most important issue.
Objective : We clarified the actual situation of diagnosis for early hilar lung cancer in Japan by a questionnaire.
Subject and Methods : We sent questionnaires to authorized and associated institutes of the Japan Society for Respiratory Endoscopy, and respondents were questioned concerning the following items. The basic items were a) the number of bronchoscopies performed, b) the number of lung cancer resections, c) the number of diagnoses of new early hilar lung cancer, d) the modes of detection, e) histological type, f) treatment modalities that can be estimated in each institute from 2006 to 2007. Moreover, to the extent possible, we ask them to respond to g) the number of advanced hilar squamous cell carcinoma, h) the number of sputum cytology examinations that were found to be positive or suspected to be positive, i) the number of peripheral lung cancer detected by sputum cytology, j) the number of cancers in otorhinological field or esophageal cancers detected by sputum cytology.
Results and the Estimated Number of Diagnosis in Japan : The questionnaires were sent to 504 authorized and associated institutes of the Japan Society for Respiratory Endoscopy and returned from 308 (61.1%) of them. These institutes, in the cases of primary lung cancer resections, covered 57.1% of the field study result of the Japanese Association of General Thoracic Surgery. A total of 150 diagnosed cases of early hilar lung cancer in a year were reported. By the reported number and the covering ratio, the number of early hilar lung cancer diagnosis was estimated between 154 and 270 cases per year. Also, 4,000 cases of hilar squamous cell carcinoma in a year in Japan were estimated. Concerning the mode of detection, sputum cytology was the most numerous, accounting for 90% of squamous cell carcinomas ; however, the rate of early cancer was less than 10% of hilar squamous cell carcinoma, and moreover, there were regional differences in the detection rates.
Conclusions : The national survey of hilar lung cancer suggested that there were 4,000 patients with hilar squamous cell carcinoma at present. However, the ratio of early cancer was less than 10%, and the regional differences in the ratio of early to not early hilar squamous cell carcinoma were also suggested. Based on these, there might have been more opportunities of early diagnosis of hilar lung cancer than were actually diagnosed. Further quality control and much more sputum cytologic examinations for lung cancer screening is recommended.
