Surgery for lung metastases from colorectal cancer: the practice examined

Operations to remove metastases in the lung have become commonplace. In this article, I give a highly critical perspective of a practice that has grown without a secure evidence base, notwithstanding more than 500 articles on the subject. The objectives are mixed and sometimes unclear. The reports are generally in the form of Kaplan-Meier survival analyses but, when challenged on the expected benefit for individuals, clinicians tend to retreat to claims for palliation rather than for 'cure'. Yet the reports include no symptom checklists, quality-of-life measures or patient-reported outcomes. I see at least four distinguishable contexts, defined by cancer types, which deserve to be considered separately: sarcoma; testicular and germ cell tumors; cancers traditionally seen as having an 'oligometastatic' pattern of behavior, such as kidney and thyroid; and the more common solid cancers, such as colorectal and breast cancer. Most surgical series group them together with a tail of one, two or three instances of the less common cancers. The inclusion in these series of all cancer types operated upon adds nothing to knowledge on cancers with low numbers and complicates the analysis for the more common ones. In this article, I will confine the discussion for the main part to colorectal cancer, which is the most common cancer in which pulmonary metastasectomy is practiced.