Synchronous and metachronous lung metastases in patients with colorectal cancer: A 20-year monocentric experience

There is little information regarding the recent trend of synchronous and metachronous pulmonary metastases in patients with primary colorectal cancer. We investigated patients with sporadic colorectal cancer who underwent surgery in our department between 1990 and 2009. Clinicopathological parameters of primary cancer and lung metastases and survival time were retrospectively reviewed. Of the 2,286 patients included in this study, 64 (2.8%) had synchronous lung metastases at the time of colorectal surgery. A total of 18 patients (28%) received pulmonary metastasectomy for these lesions with curative intent. Out of 2,082 curatively operated cases, 212 (10.2%) developed metachronous lung metastases. The frequency of synchronous and/or metachronous lung metastases detected in curative cases increased from 8.9% in the 1990s to 11.9% in the 2000s (p=0.03). Among predictive factors for metachronous lung metastases, the presence of distant organ metastases, i.e. initial stage IV, significantly increased over time. Notably, patients with unresectable metachronous lung metastases in the 2000s, characterized by smaller size, exhibited more favorable prognosis than in the 1990s (p=0.003). Recent improvement of imaging modalities is considered to have facilitated the prompt diagnosis of lung metastases. Moreover, marked progress in multidisciplinary treatment has presumably achieved more favorable prognosis in an increasing number of patients with advanced colorectal cancer.