Stage 4 NSCLC means the cancer has spread beyond the lung to distant sites (metastatic disease) or has certain patterns of spread such as pleural involvement or contralateral lung disease. Treatment is typically not framed as curative; instead, the aim is disease control, symptom relief, and longer survival. That said, Stage 4 is not uniformly “terminal” in the simplistic sense. Patients with actionable mutations may achieve durable control on targeted therapy, and those with favorable immune markers may do well with immunotherapy. In oligometastatic scenarios (limited metastatic burden), a combined approach of systemic therapy plus local treatments (radiation/surgery) may be considered in selected cases. Prognosis is best determined by biology, sites of spread, and treatment response.