Chapter 32: Lung Cancer

Lung cancer remains the leading cause of cancer mortality in North America, affecting both men and women, with most diagnoses occurring at advanced stages because early symptoms are often attributed to other conditions. Smoking represents the primary risk factor, with intensity and duration influencing disease development, while secondary exposures to tobacco smoke, radon, asbestos, and environmental pollutants contribute significantly to incidence rates. The chapter distinguishes between small-cell lung cancer, which comprises 15 to 20 percent of cases and demonstrates aggressive behavior with early metastatic spread, and non-small-cell lung cancer, representing approximately 85 percent of cases and subdivided into squamous-cell carcinoma, adenocarcinoma, and large-cell carcinoma, each with distinct anatomical locations and metastatic patterns. Clinical manifestations encompass intrathoracic symptoms such as persistent cough and hemoptysis, systemic symptoms including weight loss and fatigue, metastatic complications affecting bones and brain, and paraneoplastic syndromes resulting from tumor hormone secretion. Diagnostic evaluation incorporates low-dose computed tomography screening for high-risk populations, chest imaging, bronchoscopic evaluation, and tissue sampling techniques. The TNM classification system guides staging and treatment decisions for non-small-cell tumors, while small-cell lung cancer uses a limited-stage versus extensive-stage categorization. Management approaches include surgical resection for early-stage disease, chemotherapy regimens demonstrating significant response rates particularly in small-cell cancers, targeted molecular therapies, immunotherapy agents, and radiation therapy used alone or in combination. Long-term follow-up emphasizes monitoring for recurrence and metastatic disease while supporting smoking cessation and transitioning to palliative care when curative options are exhausted.