Lung Cancer: Complete Guide

Written by: David Martinez, MD
Reviewed by: Dr. Jennifer Park, Thoracic Oncologist
Last reviewed: January 24, 2026

Quick Facts

  • Leading cause of cancer death worldwide
  • Accounts for about 25% of all cancer deaths
  • Smoking causes 85% of lung cancer cases
  • Two main types: Non-small cell (85%) and small cell (15%)
  • Early detection through screening can reduce mortality by 20%
  • 5-year survival rate has improved to 23% overall

What is Lung Cancer?

Lung cancer is a type of cancer that begins in the lungs, typically in the cells lining the air passages. The lungs are two spongy organs in the chest that take in oxygen when you inhale and release carbon dioxide when you exhale.

Key Points

  • Lung cancer is the second most common cancer in both men and women
  • Early-stage lung cancer often has no symptoms
  • Smoking is the primary risk factor, but non-smokers can also develop lung cancer
  • Treatment advances have significantly improved outcomes in recent years

The lungs are divided into sections called lobes. The right lung has three lobes, while the left lung has two lobes. Cancer can start in any part of the lungs and may spread to lymph nodes or other organs.

Types of Lung Cancer

Non-Small Cell Lung Cancer (NSCLC) - 85% of cases

  • Adenocarcinoma (40%): Most common type, often in outer lung areas, common in non-smokers
  • Squamous Cell Carcinoma (25-30%): Usually in central lung areas near main airways
  • Large Cell Carcinoma (10-15%): Can occur in any part of the lung, tends to grow quickly

Small Cell Lung Cancer (SCLC) - 15% of cases

  • Limited Stage: Cancer confined to one lung and nearby lymph nodes
  • Extensive Stage: Cancer has spread beyond one lung

Other Rare Types

  • Carcinoid tumors (1-2% of lung cancers)
  • Adenosquamous carcinoma
  • Sarcomatoid carcinoma
  • Salivary gland carcinoma

Molecular Subtypes (Important for Treatment)

Based on genetic mutations and biomarkers:

  • EGFR-mutated (10-15% in Western populations, higher in Asian populations)
  • ALK-rearranged (3-5%)
  • ROS1-rearranged (1-2%)
  • BRAF-mutated (2-3%)
  • MET exon 14 skipping (3-4%)
  • RET-rearranged (1-2%)
  • KRAS-mutated (25-30%)
  • PD-L1 expression levels

Signs and Symptoms

Early Symptoms (May Be Subtle)

  • Persistent cough that doesn't go away
  • Cough that gets worse over time
  • Chest pain that worsens with deep breathing, coughing, or laughing
  • Hoarseness
  • Unexplained weight loss
  • Loss of appetite
  • Fatigue and weakness

Advanced Symptoms

  • Coughing up blood or rust-colored sputum (hemoptysis)
  • Shortness of breath (dyspnea)
  • Wheezing
  • Recurrent respiratory infections (bronchitis, pneumonia)
  • Swelling of face and neck (superior vena cava syndrome)
  • Difficulty swallowing
  • Bone pain (especially back, hips, ribs)
  • Headaches
  • Neurological symptoms (if spread to brain)

Paraneoplastic Syndromes

Symptoms caused by substances produced by the tumor:

  • Hypercalcemia (high calcium levels)
  • SIADH (syndrome of inappropriate antidiuretic hormone)
  • Cushing syndrome
  • Lambert-Eaton syndrome
  • Digital clubbing

⚠️ When to Seek Immediate Medical Care

Contact your healthcare provider immediately if you experience:

  • Coughing up significant amounts of blood
  • Severe shortness of breath or chest pain
  • Sudden onset of confusion or neurological symptoms
  • Signs of blood clots (leg swelling, chest pain, difficulty breathing)
  • High fever with productive cough (possible pneumonia)

Causes and Risk Factors

Primary Risk Factors

  • Smoking: Causes 85% of lung cancers
    • Risk increases with number of cigarettes and years smoked
    • Quitting reduces risk, but remains elevated compared to never-smokers
    • Cigars and pipes also increase risk
  • Secondhand Smoke: Increases risk by 20-30%
  • Radon Exposure: Second leading cause, responsible for 21,000 deaths annually
  • Occupational Exposures:
    • Asbestos (especially combined with smoking)
    • Diesel exhaust
    • Arsenic
    • Chromium compounds
    • Nickel compounds
    • Beryllium
    • Cadmium
    • Coal products
  • Air Pollution: Fine particulate matter (PM2.5)
  • Previous Radiation Therapy: To chest area for other cancers

Other Risk Factors

  • Personal or family history of lung cancer
  • Genetic susceptibility (various gene polymorphisms)
  • Pulmonary fibrosis
  • COPD or emphysema
  • HIV infection
  • Dietary factors (low fruit and vegetable intake)

Diagnosis

Initial Evaluation

  • Complete medical history and physical examination
  • Assessment of symptoms and risk factors
  • Smoking history quantification (pack-years)

Imaging Studies

  • Chest X-ray: Often first test, but can miss small tumors
  • CT Scan (Computed Tomography):
    • More detailed than X-ray
    • Can detect smaller nodules
    • Helps determine size, location, and spread
  • PET Scan (Positron Emission Tomography): Shows metabolic activity, helps with staging
  • MRI (Brain): To check for brain metastases
  • Bone Scan: If bone metastases suspected

Tissue Diagnosis (Biopsy)

  • Bronchoscopy: Flexible tube through airways to obtain samples
  • CT-guided needle biopsy: For peripheral lung lesions
  • Endobronchial ultrasound (EBUS): For lymph node sampling
  • Mediastinoscopy: Surgical procedure to sample mediastinal nodes
  • Thoracentesis: If pleural effusion present
  • Video-assisted thoracoscopic surgery (VATS): When other methods unsuccessful

Molecular Testing

Essential for treatment planning in advanced NSCLC:

  • EGFR mutations
  • ALK rearrangements
  • ROS1 rearrangements
  • BRAF V600E mutation
  • MET exon 14 skipping
  • RET rearrangements
  • KRAS G12C mutation
  • NTRK fusions
  • PD-L1 expression
  • Tumor mutational burden (TMB)

Laboratory Tests

  • Complete blood count (CBC)
  • Comprehensive metabolic panel
  • Liver function tests
  • Calcium levels
  • Lactate dehydrogenase (LDH)

Staging

Non-Small Cell Lung Cancer (TNM Staging)

Stage Description 5-Year Survival Rate
Stage 0 Cancer in situ, only in top layers of cells ~90%
Stage IA Tumor ≤3cm, no lymph nodes 68-92%
Stage IB Tumor 3-4cm, no lymph nodes 60%
Stage IIA Tumor 4-5cm, no nodes OR smaller with N1 nodes 53%
Stage IIB Tumor 5-7cm, no nodes OR smaller with N1 nodes 47%
Stage IIIA Any size, N2 nodes OR large with N1 nodes 36%
Stage IIIB Any size, N3 nodes OR T4 with N2 nodes 26%
Stage IIIC Large tumor with N3 nodes 13%
Stage IVA Single distant metastasis 10%
Stage IVB Multiple distant metastases ~5%

Small Cell Lung Cancer Staging

  • Limited Stage: Cancer confined to one hemithorax, can be encompassed in single radiation field
    • Median survival: 16-24 months
    • 5-year survival: 10-30%
  • Extensive Stage: Cancer has spread beyond limited stage definition
    • Median survival: 6-12 months
    • 5-year survival: 1-5%

Treatment Options

Surgery

Primary treatment for early-stage NSCLC:

  • Lobectomy: Removal of entire lobe (standard for early-stage)
  • Segmentectomy/Wedge resection: Removal of part of lobe
  • Pneumonectomy: Removal of entire lung (rarely needed)
  • Sleeve resection: Removal and reconstruction of airway
  • VATS or robotic surgery: Minimally invasive approaches

Radiation Therapy

  • External Beam Radiation (EBRT): Standard approach
  • Stereotactic Body Radiation (SBRT): For early-stage inoperable tumors
  • Intensity-Modulated Radiation (IMRT): Precise targeting
  • Proton Beam Therapy: Reduced dose to surrounding tissue
  • Palliative radiation: For symptom control

Chemotherapy

For NSCLC:

  • Platinum-based doublets (cisplatin or carboplatin plus):
    • Pemetrexed (non-squamous)
    • Paclitaxel
    • Gemcitabine
    • Vinorelbine
    • Docetaxel

For SCLC:

  • Etoposide + platinum (cisplatin or carboplatin)
  • Alternative: Irinotecan + platinum

Targeted Therapy

For specific genetic mutations in NSCLC:

  • EGFR inhibitors:
    • Osimertinib (Tagrisso) - preferred first-line
    • Erlotinib (Tarceva)
    • Gefitinib (Iressa)
    • Afatinib (Gilotrif)
    • Dacomitinib (Vizimpro)
  • ALK inhibitors:
    • Alectinib (Alecensa) - preferred first-line
    • Brigatinib (Alunbrig)
    • Ceritinib (Zykadia)
    • Crizotinib (Xalkori)
    • Lorlatinib (Lorbrena)
  • ROS1 inhibitors: Crizotinib, Entrectinib (Rozlytrek)
  • BRAF inhibitors: Dabrafenib (Tafinlar) + Trametinib (Mekinist)
  • MET inhibitors: Capmatinib (Tabrecta), Tepotinib (Tepmetko)
  • RET inhibitors: Selpercatinib (Retevmo), Pralsetinib (Gavreto)
  • KRAS G12C inhibitors: Sotorasib (Lumakras), Adagrasib (Krazati)

Immunotherapy

Checkpoint inhibitors for NSCLC and SCLC:

  • PD-1 inhibitors:
    • Pembrolizumab (Keytruda)
    • Nivolumab (Opdivo)
    • Cemiplimab (Libtayo)
  • PD-L1 inhibitors:
    • Atezolizumab (Tecentriq)
    • Durvalumab (Imfinzi)
  • CTLA-4 inhibitor: Ipilimumab (Yervoy) - in combination

Treatment by Stage

Early-Stage NSCLC (I-II)

  • Surgery preferred when feasible
  • Adjuvant chemotherapy for high-risk features
  • SBRT for medically inoperable patients

Locally Advanced NSCLC (III)

  • Concurrent chemoradiation
  • Durvalumab maintenance after chemoradiation
  • Surgery for selected patients

Advanced/Metastatic NSCLC (IV)

  • Targeted therapy if actionable mutation present
  • Immunotherapy ± chemotherapy based on PD-L1 expression
  • Chemotherapy alone if no targetable mutations and low PD-L1

Small Cell Lung Cancer

  • Limited stage: Concurrent chemoradiation + prophylactic cranial irradiation
  • Extensive stage: Chemotherapy + immunotherapy (atezolizumab or durvalumab)

Prognosis and Survival Rates

Factors Affecting Prognosis

  • Stage at diagnosis (most important factor)
  • Histologic type (NSCLC vs SCLC)
  • Molecular characteristics (driver mutations)
  • Performance status
  • Weight loss
  • Presence of symptoms
  • Response to treatment
  • Smoking status

Overall Survival Statistics

  • Overall 5-year survival rate: 23%
  • Localized disease: 61%
  • Regional spread: 33%
  • Distant metastases: 6%

Important Note on Statistics

Survival statistics are averages based on large groups. Individual prognosis depends on many factors, and newer treatments are continually improving outcomes. These statistics may not reflect recent treatment advances.

Prevention

Primary Prevention

  • Never smoke: Most effective prevention strategy
  • Quit smoking: Reduces risk at any age
    • Risk decreases 30-50% after 10 years of quitting
    • Never returns to never-smoker levels
  • Avoid secondhand smoke
  • Test home for radon: Mitigation if levels >4 pCi/L
  • Occupational safety: Follow safety protocols for hazardous materials
  • Healthy diet: Rich in fruits and vegetables
  • Regular exercise
  • Limit alcohol consumption

⚠️ Beta-Carotene Warning

High-dose beta-carotene supplements may increase lung cancer risk in smokers. Get nutrients from food sources rather than supplements.

Screening Guidelines

Current USPSTF Recommendations (2021)

Annual low-dose CT screening for individuals who meet ALL criteria:

  • Age 50-80 years
  • 20+ pack-year smoking history
  • Currently smoke or quit within past 15 years
  • No symptoms of lung cancer

Benefits of Screening

  • 20% reduction in lung cancer mortality
  • Detection at earlier, more treatable stages
  • Opportunity for smoking cessation counseling

Risks of Screening

  • False-positive results (95% of positive screens are false positives)
  • Overdiagnosis of indolent cancers
  • Radiation exposure
  • Anxiety from abnormal findings
  • Complications from follow-up procedures

Living with Lung Cancer

During Treatment

  • Managing treatment side effects
  • Pulmonary rehabilitation
  • Nutritional support
  • Pain management
  • Oxygen therapy if needed
  • Emotional and psychological support
  • Smoking cessation support

Follow-up Care

  • Regular CT scans (frequency depends on stage and treatment)
  • Symptom monitoring
  • Management of long-term effects
  • Surveillance for recurrence
  • Continued smoking cessation support

Quality of Life Considerations

  • Breathlessness management techniques
  • Energy conservation strategies
  • Exercise as tolerated
  • Support groups and counseling
  • Advance directive planning
  • Palliative care integration

Frequently Asked Questions

Can non-smokers get lung cancer?

Yes, about 10-20% of lung cancers occur in never-smokers. Risk factors include radon exposure, secondhand smoke, air pollution, occupational exposures, and genetic factors. Lung cancer in never-smokers is more likely to have targetable mutations.

What's the difference between NSCLC and SCLC?

NSCLC (85% of cases) grows more slowly and includes several subtypes. SCLC (15% of cases) grows rapidly, spreads quickly, and is strongly associated with smoking. Treatment approaches differ significantly between the two types.

How effective is immunotherapy for lung cancer?

Immunotherapy has revolutionized lung cancer treatment. Some patients with high PD-L1 expression achieve long-term responses. About 20-30% of advanced NSCLC patients respond to immunotherapy, with some achieving durable remissions.

Should former smokers still get screened?

Yes, if you meet the criteria (quit within 15 years, 20+ pack-year history, age 50-80). Risk remains elevated for many years after quitting, making screening valuable for early detection.

What is liquid biopsy?

Liquid biopsy is a blood test that can detect tumor DNA circulating in the bloodstream. It's increasingly used to identify genetic mutations, monitor treatment response, and detect resistance mechanisms without needing tissue biopsy.

Can lung cancer be cured?

Early-stage lung cancer can often be cured with surgery. The cure rate depends on stage: Stage I has cure rates of 60-80%, while advanced stages are rarely cured but can be controlled with treatment, sometimes for years.

What are lung nodules?

Lung nodules are small spots on the lung seen on imaging. Most (>95%) are benign. Size, growth rate, and other features help determine if a nodule needs further evaluation. Nodules under 6mm rarely require immediate action.

Related Topics

Smoking Cessation

Resources and strategies to quit smoking

Learn More →

Immunotherapy

Understanding checkpoint inhibitors

View Guide →

Clinical Trials

Find lung cancer research studies

Explore Trials →

Targeted Therapy

Precision medicine for lung cancer

Learn More →

Medical Disclaimer

This information is for educational purposes only and should not replace professional medical advice. Always consult with qualified healthcare providers for diagnosis and treatment decisions. Lung cancer treatment is rapidly evolving, and newer options may be available.

Sources

  1. National Cancer Institute. Non-Small Cell Lung Cancer Treatment (PDQ) - Health Professional Version. Updated January 2026.
  2. American Cancer Society. Lung Cancer Statistics. 2026.
  3. NCCN Clinical Practice Guidelines. Non-Small Cell Lung Cancer. Version 1.2026.
  4. US Preventive Services Task Force. Lung Cancer Screening Guidelines. JAMA. 2021.
  5. Siegel RL, et al. Cancer Statistics, 2026. CA Cancer J Clin. 2026.
  6. ASCO Guidelines. Systemic Therapy for Stage IV NSCLC. 2025 Update.
  7. IASLC Staging Manual in Thoracic Oncology. 9th Edition. 2024.