Prognostic Factors and Analysis of Microsatellite Instability in Resected Pulmonary Metastases From Colorectal Carcinoma

Background In this study, we analyze our experience with pulmonary resection for metastases from colorectal carcinoma. The aims were to search for factors influencing prognosis and to investigate the presence of microsatellite instability in the primary tumors and the corresponding lung metastases. Methods We identified 81 patients who underwent surgical resection between 1991 and 2004. The microsatellite instability was determined by immunohistochemical evaluation of MSH2 and MLH1 in 117 lesions (41 primary tumors and 76 lung metastases). Results Overall 3-, 5-, and 10-year survival rates were 50%, 42%, and 30%, respectively. Univariate analysis showed that stage of the primary tumor (p = 0.037), radicalness of the resection (p = 0.019), and stratification into groups according to the International Registry of Lung Metastases classification (p = 0.039) were prognostic factors. Multivariate analysis showed that stage of the primary tumor (p = 0.030) and the radicalness of the resection (p = 0.014) were independent prognostic factors. All tumors displayed preserved expression of MSH2 and MLH1 and were considered microsatellite stable lesions. Conclusions Pulmonary resection of metastases from colorectal carcinoma results in long-term survival in selected patients. Complete resection, stage of the primary tumor and stratification into groups according to the International Registry of Lung Metastases classification were prognostic factors. All the metastases and the corresponding primary tumors were microsatellite stable lesions. This finding seems to demonstrate that pulmonary metastases are infrequent in colorectal carcinomas with microsatellite instability.