Resection of pulmonary and hepatic metastasis in the management of cancer

Abstract

Metastasis from cancer was first reported by a French surgeon, Ledran, in 1720.’ Specific mechanisms were not postulated for another century, until Virchow delineated the cellular basis of cancer.* It soon became evident that lung and liver were the two most common sites of metastases in patients dying of malignancy. Although the natural history of most solid tumors as observed in the nineteenth and early twentieth centuries led to therapeutic approaches such as wide primary tumor and regional resection, more precise understanding of the biology of primary tumor development and metastasis has more recently justified novel adjuvant regional and systemic therapeutic approaches. However, despite the curability of many nonsolid and a few solid cancers by biologic response modifier or chemotherapy, the role of systemic treatment in advanced adult solid tumors has been disappointing. During the last two decades, numerous investigators have observed that a small proportion of patients with recurrent solid tumors present with limited regional involvement.3*4 In some of these biologically select patients with limited regional recurrence, surgical resection may be potentiaIIy curative. Among all cases of fatal malignancy, pulmonary metastasis occurs in 30%, and one-half to two-thirds of these patients have metastases that appear clinically to be confined to the 1ungs.4*5 Approximately one-half of these patients (only 5 to 10% of the total group) may be eligible for pulmonary metastasis resection with curative intent.5 The biology of pulmonary metastasis is dependent upon primary tumor histology. For instance, the pulmonary parenchyma may be the first site of metastasis in 90% of patients with disseminated sarcoma.6 In patients who recur or are first diagnosed with disseminated gastrointestinal primaries, 50% will have liver only or liver as the first site of recurrence.’ The incidence of liver metastasis at the time of primary cancer treatment varies from 20% with gastric cancer, to 25% with colorectal cancer, and up to 49% of patients with pancreatic cancer.’ Only in patients with limited liver metastases from colorectal carcinoma is regional disease not an immediate precursor of disseminated systemic recurrence. Although 60 to 70% of all patients who die of colorectal cancer have liver metastases,’ only 10 to 20% will fail only or first in the liver, and only 5 to 10% of these will be amenable to potentially curative surgical resection.9 Thus, patients with pulmonary or hepatic metastases that are resectable represent an extremely highly selected biologic subset among the overall group of patients with recurrent solid tumors. The analysis of results of pulmonary and hepatic metastasectomy must take this selection bias into account.4A In this article, we attempt to summarize the biologic rationale and the technical considerations of metastasectomy, to analyze patterns of failure after metastasectomy, and to look ahead to future therapeutic strategies based on analysis of failure. Although a variety of malignant tumors including both carcinomas and sarcomas metastatic to the lung may be cured by pulmonary resection, curative resection or metastatic tumors to the liver is limited to metastases from colorectal cancer. Anecdotal successes only have been reported after resection of isolated hepatic metastasis from renal cell cancer, various gynecologic cancers, melanoma, and sarcoma.3