We treated 472 patients with lung cancer from 1983 though 1993. Of the total number of the cases, early lung cancer accounted for 31 caces (6.6%), 6 of the hilar and 25 of the peripheral type. Of the 6 hilar type early lung cancer cases, 3 cases were detected by mass screening (2 cases were detected by sputum cytology). On the other hand, of the 25 cases of the peripheral type early lung cancer, 10 cases were detected by mass screening. All the 10 peripheral type early lung cancer cases detected by mass screening were detected by chest roentogenography. The 5-year survival rates for the hilar and peripheral type early lung cancer were 100% and 94.4%, respectively. For the improvement of prognosis of lung cancer, every effort should be made to detect lung cancer at an early stage. Careful lung cancer screening such as sputum cytology and bronchoscopy in a highrisk group and modern techniques such as helical X-ray CT are recommended for the increase in the detection of early lung cancer.

A 77-year-old man presented with fever and back pain. Computed tomography revealed a distal arch aneurysm. Bacteroides fragilis was found in a blood culture, and we diagnosed a thoracic infected aneurysm. Because of the rapid enlargement of the aneurysm and his frailty, a TEVAR procedure was urgently performed. He left the hospital after antibiotic treatment with meropenem. However, he was re-hospitalized due to recurrence of the infection. The infection was well-controlled by treatment with intravenous meropenem, and the subsequent oral administration of metronidazole (MNZ). He was re-hospitalized again 7 weeks after discharge due to unsteady gait and articulatory disorder. MNZ-induced encephalopathy (MIE) was diagnosed because FLAIR brain magnetic resonance imaging revealed an area of high signal intensity in the bilateral basal dentate nuclei. These symptoms improved after MNZ was changed to AMPC/CVA. Fifteen months later, the patient was doing well and had no recurrence of the infection. We performed TEVAR for a patient with a thoracic aneurysm infected by B. fragilis. The recurrence of the infection was controlled by adequate antibiotic therapy, which included the administration of MNZ. However, patients who are treated with MNZ should be carefully observed to detect the development of neurological signs, as MNZ may induce encephalopathy. The early detection and withdrawal of metronidazole is important for the improvement of MIE.