INTRAPULMONARY METASTASIS OF LUNG-CANCER - SOFT-X-RAY INVESTIGATION OF INFLATED AND FIXED LUNG

Background: Intrapulmonary metastasis (IPM) of lung cancer is thought to be an important factor influencing patient prognosis. It is not eas y to detect a small IPM by preoperative examination and sometimes even by postoperative pathologic investigation. We applied soft x-ray inve stigation to inflated and fixed lungs for the detection of IPM. Study Design: From 1990 to 1992, 75 patients with lung cancer who had no met astatic lesions on preoperative whole CT, MRI, and technetium-99m bone scintigram examinations underwent lung resection. The resected lungs were fixed in an inflated condition, sliced at the corresponding CT le vels into 10-mm-thick sections, and submitted for soft x-ray examinati on. When an accessory nodular shadow(s) was detected on the soft x-ray images, the size of the nodule and its distance from the primary tumo r were measured. Results: In 23 of the 75 patients, accessory nodular shadows were detected on the soft x-ray images. Six nodules in 6 patie nts proved to be IPM, 2 of which were also detected by postoperative m acroscopic examination. Another 2 microscopic IPM were found only by p ostoperative pathologic examination. The total detection rate of IPM w as 10.7% (8 of 75 patients) in this series. The detection rate of IPM at our institute was 5.4% before this study (1979 to 1989). The mean d iameter of the IPM detected by the soft x-ray method was 2.8 +/- 1.5 m m, and this was significantly smaller than that of the macroscopically detected nodules (7.2 +/- 3.2 mm). Conclusions: Our data show that so ft x-ray investigation is an effective procedure to detect relatively small intrapulmonary metastatic nodules and will contribute to precise postoperative staging of patients with lung cancer. (J Am Cell Surg 1 998;187:509-513. (C) 1998 by the American College of Surgeons).