Surgical Resection of Pulmonary Metastases
Pulmonary metastasectomy is a potentially curative surgical procedure and an accepted treatment in properly selected patients, with predictable clinical outcomes in a variety of solid tumors . Nonetheless, the role of surgical resection of pulmonary metastases is still disputed by many oncologists and surgeons on the grounds that systemic disseminated disease is already present at the time of diagnosis. Additionally, the lack of Level I evidence continues to raise questions about the absolute benefit of pulmonary metastasectomy.
The first resection of a single lung metastasis was reported by Weinlechner in 1882, during intraoperative assessment for a chest wall sarcoma. In the following 50 years, elective surgery was offered very occasionally to patients presenting with single pulmonary metastases and or a long disease-free interval.With the improvement of surgical techniques, the adoption of minimally invasive platforms, and the proven safety of limited pulmonary resections, metastasectomy gained greater popularity. Advances in imaging, as well as increased utilization of radiologic studies, have further reinforced the practice, as metastatic lung tumors are often discovered while disease remains relatively limited.
Historically, a major proof of the curative potential of metastasectomy was achieved in the management of childhood osteosarcoma, in which fatal lung metastases occurred in 80% of patients after amputation of the primary tumor. In a consecutive series of 27 patients presenting with lung metastases from osteosarcoma, systematic lung resection resulted in complete eradication of the disease in more than 80% of cases and a 45% survival rate at 5 years.Subsequent data in support of pulmonary metastasectomy has since been published for other solid tumors. However, with only limited prospective data and no published randomized controlled trials, doubt regarding the value of metastasectomy continues to exist and standard guidelines on the performance of pulmonary metastasectomy are not available. In part to address the issue, a Randomised Trial of Pulmonary Metastasectomy in Colorectal Cancer (PulMiCC) trial has enrolled patients in a two stage consent and randomization process to attempt to provide level I evidence regarding the value of surgical metastasectomy in colorectal cancer. Results of this trial are eagerly awaited to help guide future practice and research efforts.
Any discussion regarding the role of metastasectomy must be in the context of systemic treatment options. New chemotherapy regimens, which are often effective against micrometastatic foci but unable to totally eradicate the component of disease that is clinically detectable, have further expanded the role of adjuvant or salvage surgery aimed at excising the residual tumor after chemotherapy. This treatment paradigm will likely proliferate as new targeted therapies and immunotherapy are increasingly able to limit widespread tumor burden and prolong the lives of patient with metastatic disease.
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