Management of resectable colorectal lung metastases

Lung metastases occur in 10-20 % of patients with colorectal cancer. The biology of colorectal lung metastases is poorly understood, however lung metastases are more common in patients with rectal cancer and in patients with RAS mutations. Although the majority of patients have extrapulmonary disease, a small proportion of patients with lung metastases are suitable for lung metastasectomy and surgical resection has become a standard of care, based on data from retrospective series demonstrating a 5-year overall survival of 40-68 %. However, there remains uncertainty regarding the optimal management approach for these patients due to the lack of evidence from randomized controlled trials and current practice varies between institutions. For example, the role for neoadjuvant and adjuvant chemotherapy is not yet defined and there are no randomized trials comparing surgery with alternative treatment options such as radiofrequency ablation and stereotactic ablative radiotherapy. Further research is needed to improve the selection of patients for surgery, but favourable prognostic factors include a normal pre-operative CEA, solitary metastasis, complete resection and a long disease-free interval. There is also evidence that patients with resectable liver and lung metastases may benefit from resection of both sites of disease, and that re-resection may be of benefit in selected patients who relapse with resectable lung metastases. This article summarizes the biology of colorectal lung metastases and discusses the management of patients with lung metastases.