The impact of pulmnary emphysema evaluated by CT on lung metastasis in rectal cancer.

Abstract

582 Background: Our previous study suggested that smoking history could be a risk factor for pulmonary metastasis following rectal cancer surgery. Smoking causes emphysematous change in the lung, however, it remains unclear how much impact of pulmonary emphysema (PE) on the pathogenesis of pulmonary metastasis in rectal cancer. The objective of this study is to clarify the influence of PE on the pulmonary metastasis. Methods: Patients with rectal cancer who underwent curative resection from September 2005 to May 2014 in our institution were enrolled and their medical records were reviewed including the percentage volume of low attenuation area in the whole lung (LAA%), which were calculated from their preoperative chest CT by using AZE virtual place. PE was defined as more than 10% in LAA% and statistically evaluated the correlation with relapse free survival for pulmonary metastasis (RFSP). Results: A total of 286 patients, who consists of 7 in stage0,102 in StageⅠ, 75 in StageⅡ, and 102 in stageⅢ, were enrolled. The median LAA% was 3.16±3.78% and 14 patients (4.9%) were diagnosed PE by LAA%. Postoperative pulmonary metastasis was observed in 22 patients, including 3 patients in PE. Five-year RFSP rate in PE was significantly poorer than non-PE (25.4% vs 7.7%, p=0.02) by log-rank test. Multivariate survival analysis using Cox’s regression model revealed that PE was an independent risk factor for RFSP (Hazard Ratio = 19.14 [3.18 – 115.20], p < 0.001). Conclusions: Pulmonary emphysema may have a robust impact on pulmonary relapse after curative surgical resection of rectal cancer.