Lung Cancer
The leading cause of cancer deaths worldwide, primarily affecting the respiratory system
Table of Contents
Overview
Lung cancer is a type of cancer that begins in the lungs, the two spongy organs in your chest that take in oxygen when you inhale and release carbon dioxide when you exhale. It is the leading cause of cancer deaths worldwide, accounting for about 1.8 million deaths annually. While smoking is the primary risk factor, lung cancer can also occur in people who have never smoked.
The disease typically starts in the cells lining the bronchi and other parts of the lung such as the bronchioles or alveoli. Over time, abnormal cells can multiply and form tumors that interfere with lung function. Lung cancer often spreads (metastasizes) to other parts of the body before symptoms appear, making early detection challenging.
Advances in diagnosis and treatment have improved outcomes for many people with lung cancer. New targeted therapies and immunotherapies offer hope for patients with advanced disease, and screening programs can detect lung cancer early in high-risk individuals when it's most treatable. However, prevention remains the most effective strategy, particularly avoiding tobacco smoke.
Types of Lung Cancer
Major Categories
Non-Small Cell Lung Cancer (NSCLC) - 85%
The most common type of lung cancer, generally grows and spreads more slowly than small cell lung cancer. Main subtypes include:
- Adenocarcinoma (40%): Most common, often in outer lung areas, common in non-smokers
- Squamous cell carcinoma (25-30%): Usually in central lung near bronchus, strongly linked to smoking
- Large cell carcinoma (10-15%): Can occur anywhere in lung, tends to grow quickly
Small Cell Lung Cancer (SCLC) - 15%
Also called oat cell cancer, grows rapidly and spreads quickly to other parts of the body. Almost always caused by smoking. Divided into:
- Limited stage: Cancer confined to one lung and nearby lymph nodes
- Extensive stage: Cancer has spread beyond one lung
Other Types
Lung Carcinoid Tumors
Rare, slow-growing tumors that rarely spread. Account for less than 5% of lung cancers. Often called neuroendocrine tumors.
Mesothelioma
Cancer of the pleura (lung lining), usually caused by asbestos exposure. Technically not lung cancer but often grouped with it.
Symptoms
Lung cancer symptoms often don't appear until the disease is advanced, making early detection challenging:
Common Symptoms
Respiratory Symptoms
- Chronic cough: New cough or change in smoker's cough
- Chest pain: Often worse with deep breathing, coughing, or laughing
- Hoarseness: Changes in voice
- Wheezing: New onset not related to asthma
- Recurrent infections: Bronchitis or pneumonia
Systemic Symptoms
- Weight loss: Unintentional and significant
- Bone pain: Especially in back or hips
- Headache: May indicate brain metastases
- Blood clots: Increased risk
- Jaundice: If spread to liver
Paraneoplastic Syndromes
Some lung cancers produce hormones causing:
- High calcium levels (hypercalcemia)
- Low sodium levels (SIADH)
- Muscle weakness
- Neurological changes
- Skin changes
Seek Medical Attention For:
- Persistent cough lasting more than 3 weeks
- Coughing up blood, even small amounts
- Unexplained weight loss
- Persistent chest pain
- Recurring respiratory infections
Causes and Risk Factors
Lung cancer results from genetic changes in lung cells, often due to carcinogen exposure:
Primary Risk Factors
Smoking
- Leading cause: Responsible for 80-90% of lung cancer deaths
- Risk level: 15-30 times higher risk than non-smokers
- Duration matters: Risk increases with years smoked and cigarettes per day
- Secondhand smoke: Increases risk by 20-30%
- Other tobacco: Pipes, cigars also increase risk
Environmental and Occupational
- Radon gas: Second leading cause, naturally occurring radioactive gas
- Asbestos: Especially dangerous combined with smoking
- Carcinogens: Arsenic, chromium, nickel, diesel exhaust
- Air pollution: Long-term exposure increases risk
- Radiation: Previous chest radiation therapy
Other Risk Factors
- Family history: Genetic predisposition
- Personal history: Previous lung cancer or COPD
- Age: Most diagnosed after age 65
- Gender: Historically higher in men, gap narrowing
- Race: Higher in Black men, lower in Black women
Protective Factors
- Never smoking
- Quitting smoking at any age
- Avoiding secondhand smoke
- Testing home for radon
- Workplace safety measures
- Healthy diet rich in fruits and vegetables
Stages
Staging determines the extent of cancer spread and guides treatment decisions:
Non-Small Cell Lung Cancer Stages
Stage I
- Cancer confined to lung
- No lymph node involvement
- IA: Tumor ≤3 cm
- IB: Tumor 3-4 cm
Stage II
- Larger tumor or spread to nearby lymph nodes
- IIA: Tumor 4-5 cm or smaller with lymph nodes
- IIB: Tumor 5-7 cm or spread to specific areas
Stage III
- Spread to lymph nodes in chest center
- IIIA: Operable in some cases
- IIIB: Usually inoperable
- IIIC: Extensive lymph node involvement
Stage IV
- Spread to other lung or distant organs
- IVA: Limited metastases
- IVB: Widespread metastases
Small Cell Lung Cancer Stages
Limited Stage
Cancer in one lung and nearby lymph nodes on same side of chest. Can be treated with radiation to single field.
Extensive Stage
Cancer has spread throughout lung, to other lung, to lymph nodes on other side, or to distant organs.
Diagnosis
Lung cancer diagnosis involves multiple tests to confirm cancer and determine its type and stage:
Screening
Low-Dose CT Scan
Annual screening recommended for high-risk individuals:
- Age 50-80 years
- 20+ pack-year smoking history
- Currently smoke or quit within 15 years
Diagnostic Tests
Imaging Studies
- Chest X-ray: Often first test, may show mass
- CT scan: Detailed lung images
- PET scan: Shows cancer activity
- MRI: Brain or bone metastases
Tissue Diagnosis
- Bronchoscopy: Camera examines airways
- Needle biopsy: CT-guided sampling
- Thoracentesis: Fluid around lung
- Mediastinoscopy: Lymph node sampling
- Thoracoscopy: Surgical biopsy
Molecular Testing
Essential for treatment planning:
- EGFR mutations
- ALK rearrangements
- ROS1 rearrangements
- BRAF mutations
- PD-L1 expression
- Other targetable alterations
Staging Workup
- Brain MRI
- Bone scan or PET scan
- Pulmonary function tests
- Blood tests
- Molecular profiling
Treatment
Treatment depends on cancer type, stage, molecular features, and patient health:
Surgery
Types of Surgery
- Wedge resection: Small section of lung
- Segmentectomy: Larger portion
- Lobectomy: Entire lobe (most common)
- Pneumonectomy: Entire lung
- VATS: Minimally invasive approach
Radiation Therapy
Types and Uses
- External beam: Standard approach
- SBRT: High-dose precision for early stage
- Adjuvant: After surgery
- Palliative: Symptom relief
- Brain radiation: For metastases
Systemic Therapy
Chemotherapy
- Platinum-based combinations
- Adjuvant after surgery
- Combined with radiation
- Palliative for advanced disease
Targeted Therapy
For specific genetic mutations:
- EGFR inhibitors: Erlotinib, osimertinib
- ALK inhibitors: Alectinib, brigatinib
- ROS1 inhibitors: Crizotinib, entrectinib
- BRAF inhibitors: Dabrafenib + trametinib
Immunotherapy
- PD-1/PD-L1 inhibitors: Pembrolizumab, nivolumab
- CTLA-4 inhibitors: Combined approaches
- First-line: For high PD-L1 expression
- Combination: With chemotherapy
Treatment by Stage
- Stage I-II: Surgery preferred, radiation if inoperable
- Stage III: Combined chemotherapy and radiation, sometimes surgery
- Stage IV: Systemic therapy based on molecular profile
- Small cell: Chemotherapy ± radiation, immunotherapy
Prognosis
Survival rates have improved with advances in treatment, especially for certain molecular subtypes:
5-Year Survival Rates (NSCLC)
- Localized (Stage I-II): 60-65%
- Regional (Stage III): 35%
- Distant (Stage IV): 7%
- Overall: 25%
Factors Affecting Prognosis
- Stage at diagnosis: Most important factor
- Histology: Type of lung cancer
- Molecular markers: Targetable mutations
- Performance status: Overall health
- Response to treatment: Initial response predicts outcome
- Smoking status: Continued smoking worsens prognosis
Improving Outcomes
- Earlier detection through screening
- Molecular profiling for targeted therapy
- Immunotherapy breakthroughs
- Improved surgical techniques
- Better supportive care
Prevention
Most lung cancer cases are preventable through lifestyle modifications:
Primary Prevention
- Don't smoke: Never start or quit as soon as possible
- Avoid secondhand smoke: Support smoke-free environments
- Test for radon: Mitigate if levels high
- Workplace safety: Use protective equipment
- Healthy diet: Rich in fruits and vegetables
- Exercise regularly: May reduce risk
Smoking Cessation
- Benefits begin immediately: Risk decreases after quitting
- Support available: Counseling, medications, apps
- Multiple attempts normal: Average 7-10 quit attempts
- Combination therapy: Most effective approach
Secondary Prevention
- Annual screening for high-risk individuals
- Know warning signs
- Regular check-ups
- Prompt evaluation of symptoms
Living With Lung Cancer
Managing lung cancer involves comprehensive care addressing physical and emotional needs:
Symptom Management
- Breathlessness: Oxygen therapy, breathing exercises
- Pain: Medications, radiation for bone pain
- Fatigue: Energy conservation, mild exercise
- Cough: Suppressants, humidification
- Appetite loss: Small frequent meals, nutrition supplements
Treatment Side Effects
- Nausea: Anti-emetics, dietary changes
- Neuropathy: From chemotherapy, manage carefully
- Skin changes: From targeted therapy or radiation
- Immune effects: Monitor for immunotherapy side effects
Emotional Support
- Counseling or therapy
- Support groups
- Family involvement
- Spiritual care if desired
- Palliative care team
Practical Considerations
- Work accommodations
- Financial planning
- Advance directives
- Transportation to treatments
- Home modifications