Extending surgery for pulmonary metastasectomy: what are the limits?

The purpose of pulmonary metastasectomy is to remove all known remaining cancer with the purpose of cure or tolengthen survival. Little information is available on the extent ofsurgery that is justified and or on reasonable evidence based limitsto the extent of surgery.Methods: A systematic review was designed to evaluate the role ofextended surgery in the treatment of lung metastasis. For thisanalysis, the following three research questions were formulated.Q1) Is pneumonectomy indicated for pulmonary metastasectomy?Q2) What is the number of repeat operations justified and whatmight be the criteria?Q3) What number of individual metastases is it justified to removein a single procedure? A MEDLINE search of English languagearticles was conducted using key words appropriate to the threequestions posed. We excluded reports with little or no data,single cases, small series, and review articles without data.Results: Most information concerning extremes of surgery is in theform of case reports, small series, or sporadic cases within aretrospective report of a larger group of patients undergoing pulmonarymetastasectomy. Meta-analysis was ruled out because of theinsufficient quantity and quality of data in the available literature.Q1) extended resection for pulmonary metastasis is feasible and maybe justified in individualized circumstances. We believe cautionis warranted before performing pneumonectomy because it isdebatable whether any possible benefit justifies the adverseconsequences of this surgery and long-term survival is poor.Q2) multiple attempts to re-establish intrathoracic control of metastaticdisease supported by some authors in carefully selectedpatients, but apparent benefit may be a result of survivor bias,and the ratio of harm to benefit is likely to increase with eachsubsequent attempt.Q3) if on accepted criteria specific to the primary cancer the patientis a candidate for pulmonary metastastasecomy, then the goalshould be to resect all metastases that are there, irrespective ofthe 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.Conclusions: Evidence-based recommendations for extended treatmentof lung metastasis are at best weak. We have summarized theavailable data to provide the most up to date information regardingextended surgery in an attempt to define limits in the treatment oflung metastasis.