Routine clinical use of computed tomography (CT) has recently made detection of many small pulmonary nodules possible. There however have been no proven preoperative indicators on postoperative survival of patients with a small lung cancer. We therefore investigated prognostic determinants detected preoperatively on CT images in such patients.
Of 952 consecutive patients operated on for primary lung cancer, 167 patients with a proven adenocarcinoma 3 cm or less in diameter underwent complete removal of the primary tumor. We examined their CT scans to estimate tumor shadow disappearance rate (TDR) which was defined as the ratio of the tumor area of the mediastinal window to that of the lung window, reviewed the clinical records and evaluated their relation to prognosis.
On univariate analyses, size of the tumor (p=0.0380), TDR (p=0.0018), and carcinoembryonic antigen (p=0.0001) and pathologic stage (p<0.0001), nodal involvement (p<0.0001), lymphatic invasion (p=0.0001), and vascular invasion (p=0.0017) were significantly associated with prognosis. Also, the outcomes of multivariable analyses for preoperative factors indicated that TDR (p=0.0340), and CEA (p=0.0047) are significant independent prognostic determinants. The 5-year survival was 48% in cases with a TDR of 0 to 25%, 87% in those with a TDR of 26 to 50%, 97% in those with a TDR of 51 to 75%, and 100% in those with a TDR of 76 to 100%. The incidence of lymphatic, vascular invasion, and nodal metastases was lower in patients with a higher TDR.CONCLUSIONS: Small-sized adenocarcinomas with a higher TDR showed less lymphatic, vascular vessel invasion or nodal involvement, and demonstrated longer survival, suggesting that TDR was associated with clinical-pathologic characteristics and tumor aggressiveness.
Preoperative assessment of TDR may be useful to identify an appropriate candidate for a lesser pulmonary resection.
M. Okada, None.