Epidemiology, management and prognosis of colorectal cancer with lung metastases: a 30-year population-based study

OBJECTIVE: Epidemiological data on synchronous and metachronous lung metastases from colorectal cancer are scarce. The aim of this study was to determine trends in the incidence, treatment and survival in colorectal cancer with lung metastases in the general population. DESIGN AND PATIENTS: All cases of lung metastases from colorectal cancer registered in the Burgundy digestive cancer registry between 1976 and 2005 were included. Trends in the incidence of synchronous colorectal cancer lung metastases were estimated. A Cox model was used to analyse the risk of developing a metachronous metastasis. Multivariate analyses were performed using a relative survival model with proportional hazard applied to the net survival by interval. RESULTS: Overall, 11.0% of patients had synchronous lung metastases. The frequency of synchronous lung metastases significantly increased for both sexes over time, with a nearly threefold increase between the periods 1976-1985 and 1996-2005. The overall 5-year cumulative risk of developing metachronous lung metastases was 5.8%. It did not significantly vary with time. Compared to colon cancer, rectal cancers had a higher risk of developing synchronous (OR: 2.80 (1.65-4.76)) and metachronous (OR: 2.63 (1.69-4.08)) lung metastases. Overall, 4.1% of synchronous lung metastases and 14.3% of metachronous lung metastases were resected for cure. The 3-year relative survival was 11.3% for synchronous lung metastases and 13.8% for metachronous lung metastases. It was, respectively, 53.0% and 59.2% after resection for cure. In multivariate analysis, the relative risk of death for the 1996-2005 period was about one fifth of that for the 1976-1985 period. CONCLUSIONS: The incidence of synchronous lung metastases increased over time, whereas the incidence of metachronous lung metastases remained stable. Lung metastases were more frequent in rectal cancer than in colon cancer. Unless surgical resection is possible, the prognosis for lung metastases remains very poor.