Non-Small Cell Lung Cancer
The most common type of lung cancer, encompassing adenocarcinoma and squamous cell carcinoma, frequently linked to smoking but heavily treated with new targeted and immunotherapies.
Emergency Management: Massive hemoptysis requiring bronchial artery embolization. Spinal cord compression requiring emergency IV Dexamethasone and urgent radiation or neurosurgery.
Non-small cell lung cancer (NSCLC) is a broad category of lung malignancies derived from epithelial cells, accounting for approximately 85% of all lung cancers. The major histological subtypes include adenocarcinoma, squamous cell carcinoma, and large cell carcinoma.
Detailed Overview
NSCLC is the leading cause of cancer-related death worldwide. Adenocarcinoma is the most common subtype and often occurs in peripheral lung tissue; it is also the most common lung cancer in non-smokers. Squamous cell carcinoma typically arises centrally in the major bronchi and is strongly linked to smoking. NSCLC is characterized by a slower growth rate compared to small cell lung cancer but is frequently diagnosed at an advanced stage. The therapeutic landscape has been revolutionized by targeted therapies (targeting EGFR, ALK, ROS1) and immune checkpoint inhibitors.
Epidemiology & Demographics
Accounts for 85% of the ~230,000 new lung cancer cases in the US annually. Median age at diagnosis is 70 years. Lifetime risk is 1 in 15 for men and 1 in 17 for women.
Etiological Mechanism
Genomic instability in lung epithelial cells primarily caused by carcinogens in tobacco smoke. In non-smokers, driver mutations (e.g., EGFR, ALK, KRAS) play a predominant role.
Primary Causes
Tobacco smoke containing over 60 known carcinogens (e.g., nitrosamines, polycyclic aromatic hydrocarbons). Radon gas exposure is the second leading cause.
Repeated exposure to carcinogens induces DNA damage, causing normal bronchial or alveolar epithelium to undergo metaplasia, dysplasia, and ultimately malignant transformation. Adenocarcinoma arises from alveolar type II pneumocytes or Club cells, often driven by KRAS or EGFR mutations. Squamous cell carcinoma arises from bronchial epithelium undergoing squamous metaplasia, often demonstrating p53 mutations, keratin pearls, and intercellular bridges. Tumors can grow locally to invade the pleura, chest wall, or mediastinum, and metastasize via lymphatics and blood to the brain, bone, liver, and adrenal glands.
Diagnostic Criteria & Guidelines
Requires tissue biopsy (via bronchoscopy, CT-guided core biopsy, or surgical resection) confirming malignant non-small cell histology, followed by molecular testing (NGS) and staging imaging.
Stage I-II: Surgical resection (lobectomy with mediastinal lymph node dissection) +/- adjuvant chemotherapy (e.g., Cisplatin/Pemetrexed) or adjuvant immunotherapy (Atezolizumab) / targeted therapy (Osimertinib if EGFR+). Stage III: Concurrent chemoradiation followed by consolidation Durvalumab. Stage IV: Dependent on molecular profile. If driver mutation present (e.g., EGFR+): Osimertinib 80mg PO daily. If no mutation and PD-L1 >=50%: Pembrolizumab 200mg IV q3w mono-therapy. If PD-L1 <50%: Pembrolizumab + Carboplatin/Pemetrexed.
Second-Line & Adjunctive Therapy
For progression on targeted therapy: switch to next-generation TKI or Platinum doublet chemotherapy. For progression on immunotherapy: Docetaxel 75 mg/m2 IV q3w + Ramucirumab.
Surgical & Procedural Management
Lobectomy via Video-Assisted Thoracoscopic Surgery (VATS) or robotic approach is the gold standard for early-stage disease. Pneumonectomy if required for central tumors.
Patient Counseling & Advice
Explain that molecular testing takes 2-3 weeks but is crucial to define the optimal therapy for advanced disease. Discuss the potential side effects of immunotherapy, notably autoimmune pneumonitis and thyroiditis.
Follow-Up & Monitoring Schedule
Surveillance CT chest every 6 months for 2-3 years, then annually. Clinical evaluation for late toxicities of therapy.
Preventive Strategies
Smoking cessation. Lung cancer screening with annual Low-Dose CT for adults 50-80 years with >=20 pack-year smoking history who currently smoke or quit within the past 15 years.
Overall 5-year survival is 25%. Stage I is >70%, whereas Stage IV is roughly 5-10% (though improving significantly with targeted and immunotherapies).