SURGERY FOR OLIGOMETASTATIC DISEASE NON–SMALL CELL LUNG CANCER
What is oligometastatic non–small cell lung cancer (NSCLC)?
What clinicopathological features are suggestive of oligometastatic disease?
How does the eighth edition of the TNM (tumor, node, metastasis) staging system account for this concept?
How can the clinician determine whether 2 foci of lung cancer represent metastatic disease or independent primary tumors?
What is the ideal treatment approach and extent of resection in this subgroup of patients?
DEFINITION OF OLIGOMETASTATIC DISEASE
Most patients with advanced NSCLC receive systemic therapies as primary treatment, with therapeutic goals focused on palliation. However, it is becoming increasingly evident that patients with stage III-IV NSCLC are a heterogeneous group in regard to disease burden and prognosis. In its eighth edition, the TNM staging system was updated to reflect the diversity in this patient population, increasing our capacity to refine prognosis. Radiologic and therapeutic advances such as positron emission tomography (PET) and immunotherapy have improved survival for many patients with advanced lung cancer and led some to reconsider surgical intervention with curative intent for select patients with advanced NSCLC.1,2 In this chapter, we define oligometastatic disease, summarize the current literature regarding the role of surgical resection, and discuss key considerations in the surgical management of patients with suspected oligometastatic NSCLC.
The term oligometastatic disease was first introduced by Hellman and Weichselbaum in 1995 to describe patients with a more indolent tumor biology and limited number of metastases that could be amenable to cure by means of local surgical therapies.3 “In these cases the slow progression of the malignancy raises the opportunity for an aggressive local approach to control the disease” (page 9). While no clear consensus on the criteria defining oligometastatic disease has been reached, the patients most often included in this category are those with 1-5 metastases, locally advanced stage III, and metachronous second primary lung cancer (SPLC). There is growing evidence to suggest that oligometastatic lung cancer is a biologically and clinically distinct entity, which may redefine the prognosis and treatment approaches for many patients with historically incurable disease. Several studies have demonstrated long-term survival in certain patients with stage III and IV NSCLC following definitive surgical resection of both locoregional and distant metastases. Early evidence is, however, based almost exclusively on retrospective series, limiting conclusions on which patients benefit most from surgery and the most effective treatment approaches. As our understanding of oligometastatic NSCLC improves, characterization of predictable and reliable prognostic factors may facilitate proper patient selection.
DIAGNOSIS OF OLIGOMETASTATIC DISEASE
Identifying patients with oligometastatic disease is clinically challenging. Many patients presenting with apparent oligometastatic lung cancer progress to overtly metastatic disease. Objective predictors of the rate of metastatic progression are necessary to improve selection of patients who may achieve long-term disease control with aggressive oligometastasis-directed surgical therapy. Ashworth et al. conducted a meta-analysis characterizing outcomes ...