Background: The proportion of tumor disappearance rate (TDR) on conventional computed tomography (CT) is associated with less aggressive biology, and patients with small peripheral adenocarcinoma accompanied by the TDR component showed better prognosis. These findings led us to the idea that even advanced-stage adenocarcinomas with a higher TDR in the primary lesion on CT might suggest slowly progressing cancer. This study was designed to determine the value of the TDR area in the primary site of advanced-stage lung adenocarcinoma with CT and correlate the CT findings with clinical outcome.
Patients and methods: In 103 patients with stage IIIB and IV lung adenocarcinoma, CT appearances and clinical data were reviewed retrospectively. Three methods were used in the evaluation of the TDR area: method I, consolidation on mediastinal windows/mass on lung windows > 75% or not; method II, maximum diameter on mediastinal windows/maximum diameter on lung windows (diameter ratio) > 75% or not; and method III, TDR area on lung windows > 25% or not.
Results: In univariate analysis, patients with lung adenocarcinoma with TDR have a more favorable prognosis than those without TDR in all 3 methods (method I, P = 0.001; method II, P = 0.024; method III, P = 0.014; log-rank test). In multivariate analysis, a favorable prognosis in patients with adenocarcinoma with TDR was shown in method I (P = 0.015) and method III (P = 0.006).
Conclusion: As shown in patients with small peripheral lung adenocarcinoma, those with TDR on CT tended to have a good prognosis in contrast to those without TDR, even in patients with advanced-stage lung adenocarcinoma. Prospective study to confirm these results will be required.