78: Pulmonary Metastasectomy

Introduction

The recognition of pulmonary metastases from an extrathoracic primary tumor is a dramatic and emotional change in the care of the cancer patient. The clinical situation immediately changes from potential cure to the tacit acknowledgment of probable incurability. Goals of therapy change from living without evidence of disease to living, and living well, with systemic disease. We believe that pulmonary metastasectomy in carefully selected patients contributes to quality of life and may give the patient extended periods of time without obvious disease.

Many primary tumors metastasize to specific target organs.¹ In the 1930s, it was noted that patients dying of pulmonary metastases frequently failed to exhibit extrapulmonary disease at autopsy.² As a result, several surgeons felt that it would be reasonable to offer surgical resection of these lesions in the hope of prolonging survival. The first reported pulmonary metastasectomy removed a single renal cell metastasis in 1930, and the patient lived for two more decades.³ Interest in this surgical approach was increased with the development of systemic adjuvant chemotherapy, which appeared to increase survival.

The role of surgical resection of metastatic disease, however, is not universally accepted in the nonsurgical community. No randomized trial has been constructed to establish a survival advantage of pulmonary metastasectomy. In fact, the multitude of variables that would have to be included in the eligibility criteria (e.g., number of metastases, cell type, disease-free interval [DFI], cardiorespiratory reserve) makes it unlikely that a randomized trial of this nature will ever be performed. Without such data, however, some authors remain skeptical that surgical resection adds significant benefit.^4,5 Opponents to this approach point out that larger trials claiming improved survival after metastasectomy have been conducted in heterogeneous populations with tumors of mixed histologic types and mixed doubling times. The patients who benefit the most from surgical resection have a small tumor burden and a long doubling time (DFI), and this group may be able to live a long time with their disease even without surgical resection. The skeptics argue that a hypothetical study population that included slow-growing tumors in 40% of the subjects would produce a 30% 5-year survival after surgery, and that same 30% also would still be alive without an operation.

These arguments highlight the heterogeneity of this patient population and emphasize the need to tailor the surgical approach to each individual patient. Patients with dozens of metastases or rapid recurrence after a previous pulmonary metastasectomy will not gain major benefit from surgery. A very elderly patient with a slow-growing metastasis that would require pneumonectomy for resection might be better treated in other ways. These exceptions still leave many patients with pulmonary metastases that can be removed safely with an anticipated low morbidity and mortality.⁶

A large volume of retrospective data is available to substantiate a significant long-term survival with pulmonary metastasectomy. When these data are compared with those ...