Extending Surgery for Pulmonary Metastasectomy: What Are the Limits?

IntroductionThe purpose of pulmonary metastasectomy is to remove all known remaining cancer with the purpose of cure or to lengthen survival. Little information is available on the extent of surgery that is justified and or on reasonable evidence based limits to the extent of surgery.MethodsA systematic review was designed to evaluate the role of extended surgery in the treatment of lung metastasis. For this analysis, the following three research questions were formulated.Q1)Is pneumonectomy indicated for pulmonary metastasectomy?Q2)What is the number of repeat operations justified and what might be the criteria?Q3)What number of individual metastases is it justified to remove in a single procedure? A MEDLINE search of English language articles was conducted using key words appropriate to the three questions posed. We excluded reports with little or no data, single cases, small series, and review articles without data.ResultsMost information concerning extremes of surgery is in the form of case reports, small series, or sporadic cases within a retrospective report of a larger group of patients undergoing pulmonary metastasectomy. Meta-analysis was ruled out because of the insufficient quantity and quality of data in the available literature. Q1)extended resection for pulmonary metastasis is feasible and may be justified in individualized circumstances. We believe caution is warranted before performing pneumonectomy because it is debatable whether any possible benefit justifies the adverse consequences of this surgery and long-term survival is poor.Q2)Q2) multiple attempts to re-establish intrathoracic control of metastatic disease supported by some authors in carefully selected patients, but apparent benefit may be a result of survivor bias, and the ratio of harm to benefit is likely to increase with each subsequent attempt.Q3)Q3) if on accepted criteria specific to the primary cancer the patient is a candidate for pulmonary metastastasecomy, then the goal should be to resect all metastases that are there, irrespective of the number. However, with increasing pulmonary metastatic count, there is less good survival and greater loss of lung tissue. These issues should be fully considered at the planning stage.ConclusionsEvidence-based recommendations for extended treatment of lung metastasis are at best weak. We have summarized the available data to provide the most up to date information regarding extended surgery in an attempt to define limits in the treatment of lung metastasis.