Prognostic factors after pulmonary metastasectomy for colorectal cancer and rationale for determining surgical indications: a retrospective analysis.

Objective: We aimed to identify prognostic factors after pulmonary metastasectomy for colorectal cancer and propose the clinical application of them. Furthermore, we endeavored to provide a rationale for pulmonary metastasesectomy.

Background: Several prognostic factors have been proposed, but clinical application of them remains unclear. Moreover, there is no theoretical evidence that pulmonary metastasectomy is indicated for colorectal cancer.

Methods: We retrospectively analyzed 1030 patients who underwent pulmonary metastasectomy for colorectal cancer from 1990 to 2008. Prognostic factors were identified and the relationship of recurrent sites after pulmonary resection to pulmonary tumor size was assessed.

Results: Overall 5-year survival was 53.5%. Median survival time was 69.5 months. Univariate analysis showed tumor number (P < 0.0001), tumor size (P < 0.0001), prethoracotomy serum carcinoembryonic antigen (CEA) level (P < 0.0001), lymph node involvement (P < 0.0001), and completeness of resection (P < 0.0001) to significantly influence survival. In multivariate analysis, all remained independent predictors of outcome. In patients whose recurrent sites extended downstream from the lung via hematogenous colorectal cancer spread, pulmonary tumor size was significantly larger than in those with recurrent sites confined to the lung and regions upstream from the lung.

Conclusions: We should utilize these prognostic factors to detect patients who might benefit from surgery. Therefore, we should periodically follow up advanced colorectal cancer patients by chest computed tomography to detect small pulmonary metastases before serum CEA elevation. Metastases to the lung or organs upstream from the lung are regarded as semi-local for colorectal cancer. This concept provides a rationale for validating surgical indications for pulmonary metastases from colorectal cancer.