Introduction
Lung cancer begins when cells in the lungs grow uncontrollably, forming tumours that can invade nearby tissue and spread to lymph nodes and distant organs. It is one of the leading causes of cancer death worldwide, largely because many cases are diagnosed at advanced stages.
The two main types are non-small cell lung cancer (NSCLC), which includes adenocarcinoma and squamous cell carcinoma, and small cell lung cancer (SCLC), which grows faster and spreads earlier. Treatment and prognosis differ significantly between types.
Smoking is the strongest risk factor, but non-smokers can develop lung cancer—often with targetable genetic mutations. Early symptoms may be absent; persistent cough, chest pain, breathlessness, or coughing blood should prompt medical evaluation.
This page covers symptoms, diagnosis, staging, treatment options (surgery, chemotherapy, targeted therapy, immunotherapy, radiation), screening for high-risk individuals, and prevention.
Overview
Diagnosis requires imaging (chest X-ray, CT, PET) and tissue biopsy. Molecular testing on NSCLC samples guides targeted drugs and immunotherapy choices.
Staging uses TNM for NSCLC and limited versus extensive stage for SCLC. Early-stage localized disease has substantially better survival than metastatic disease.
Treatment is multidisciplinary. Even advanced lung cancer outcomes are improving with immunotherapy and targeted agents. Smoking cessation at any stage improves treatment tolerance and overall health.
- Major types: NSCLC (~85%) and SCLC (~15%)
- Often asymptomatic early; symptoms may mean advanced disease
- Diagnosis: imaging + biopsy + molecular testing for NSCLC
- NSCLC staged I–IV with TNM; SCLC limited vs extensive
- Treatment: surgery, chemo, radiation, targeted therapy, immunotherapy
- Screening LDCT for high-risk smokers per guidelines
- Leading risk: tobacco; also radon, occupational exposures
- Non-smokers: EGFR, ALK, ROS1 mutations may enable targeted therapy
What happens in the body
Carcinogens in tobacco smoke and other exposures damage lung DNA, causing mutations that disable tumour suppressors and activate oncogenes. Abnormal cells evade immune surveillance and proliferate.
Angiogenesis feeds tumours; cells can invade blood and lymph channels, metastasizing to brain, bone, liver, and adrenal glands. SCLC has early widespread micrometastases even when the chest tumour seems localized.
- Repeated carcinogen exposure causes cumulative genetic mutations
- Immune checkpoint dysregulation allows tumour escape from immunity
- Lymphatic and hematogenous spread to distant organs
- Molecular drivers (EGFR, ALK, etc.) define subset of NSCLC
Signs and symptoms
Symptoms may reflect local lung effects or distant spread:
- Persistent cough or change in chronic cough
- Chest, shoulder, or back pain not explained by cough strain
- Shortness of breath or wheezing
- Hoarseness lasting weeks
- Coughing up blood (hemoptysis)—urgent evaluation
- Unexplained weight loss and appetite loss
- Fatigue and recurrent infections (pneumonia, bronchitis)
- Bone pain from metastases
- Headache, dizziness, seizures, or personality change (brain metastases)
- Jaundice if liver involved
- Swelling of face or neck from superior vena cava syndrome
- Clubbing of fingers in some cases
- Many early-stage patients have no symptoms at all
Causes and risk factors
Risk reflects carcinogen exposure and individual susceptibility:
- Active cigarette smoking—dose and duration related
- Secondhand smoke exposure
- Radon gas in homes
- Occupational asbestos, silica, diesel exhaust, arsenic
- Prior radiation therapy to chest
- Family history of lung cancer
- Chronic lung disease: COPD, pulmonary fibrosis
- Air pollution (contributory)
- HIV and other immunosuppression (modest increase)
- Age—most cases in older adults
- Never-smoker adenocarcinoma with spontaneous mutations
Diagnosis and evaluation
Workup confirms cancer type, stage, and actionable mutations:
- Medical history and smoking pack-year calculation
- Physical exam and assessment of performance status
- Chest X-ray often first test showing mass or collapse
- Chest CT with contrast for tumour size and lymph nodes
- PET-CT to detect metastases when staging NSCLC
- Tissue biopsy via bronchoscopy, CT-guided needle, or surgical biopsy
- Pathology distinguishes NSCLC vs SCLC and subtype
- Molecular testing: EGFR, ALK, ROS1, BRAF, PD-L1, others in NSCLC
- Brain MRI when staging advanced disease or neurologic symptoms
- Pulmonary function tests before surgery
- Staging determines treatment pathway
Treatment and management
Personalised multimodal therapy by type and stage:
- Early NSCLC: surgical lobectomy or segmentectomy; VATS minimally invasive options
- Adjuvant or neoadjuvant chemotherapy and/or immunotherapy for selected stages
- Radiation for inoperable localized disease or after incomplete resection
- Stereotactic body radiation (SBRT) for small early tumors in non-surgical candidates
- Advanced NSCLC: platinum chemotherapy plus immunotherapy combinations
- Targeted oral agents for EGFR, ALK, ROS1, and other mutations
- Immune checkpoint inhibitors (PD-1/PD-L1) alone or combined
- SCLC: chemo plus radiation for limited stage; immunotherapy added in extensive stage
- Palliative radiation for bone pain, brain metastases, or airway obstruction
- Supportive care: pain control, nutrition, pulmonary rehab, smoking cessation support
- Clinical trials for novel therapies when standard options limited
- Ongoing surveillance imaging after treatment for recurrence detection
Prevention, self-care, and lifestyle
Not every condition is fully preventable, but the steps below may lower risk or recurrence:
- Quit smoking—the single most effective prevention step; risk falls over time after quitting
- Avoid secondhand smoke and occupational carcinogens with proper protection
- Test home radon and mitigate high levels
- Follow lung cancer screening guidelines if high-risk smoker (LDCT annually in eligible adults)
- Healthy diet and exercise support overall health though do not eliminate smoking risk
Possible complications
Delay, missed care, or unsafe self-medication can raise the chance of complications in some cases:
- Local invasion: airway obstruction, pleural effusion, hemoptysis
- Distant metastases to brain, bone, liver, adrenal glands
- Paraneoplastic syndromes (hypercalcemia, SIADH, neurologic syndromes)
- Treatment side effects: neutropenia, fatigue, pneumonitis from immunotherapy
- Recurrence after initial remission
- Death when advanced disease not responsive to therapy
When to see a doctor or seek emergency care
Seek prompt medical advice or emergency care if any of the following apply—it is safer not to wait and see:
- Persistent cough beyond 3 weeks or change in chronic cough
- Coughing blood—even small amounts
- Unexplained chest pain, breathlessness, or weight loss
- Hoarseness or wheezing without clear infection cause
- High-risk smoker with new respiratory symptoms—low threshold for evaluation
- Eligible for screening: discuss annual LDCT with your clinician
- Neurological symptoms suggesting brain metastases—urgent imaging
Living with the condition
Lung cancer treatment is exhausting—build a support team for transport, meals, and appointment tracking.
If you smoke, quitting during treatment improves surgical healing and chemotherapy tolerance; nicotine replacement and counselling help.
Survivorship care includes monitoring for recurrence, managing late effects, and addressing anxiety or depression with professional support.
Frequently asked questions
Can lung cancer be cured?
Yes, especially when found early and removed by surgery. Advanced disease is harder to cure but many people live longer with modern therapies.
Do non-smokers get lung cancer?
Yes. A significant fraction occurs in never-smokers, often adenocarcinoma with targetable mutations.
What is a pack-year?
Packs smoked per day multiplied by years smoked. Used to assess screening eligibility (e.g., 20 pack-years).
What is the difference between NSCLC and SCLC?
NSCLC is more common and slower; SCLC is aggressive with early spread. Treatments differ substantially.
What are targeted therapy and immunotherapy?
Targeted drugs attack specific mutations in cancer cells. Immunotherapy helps your immune system recognize and fight cancer.
Should I get screened?
Annual low-dose CT is recommended for high-risk adults aged 50–80 with significant smoking history per major guidelines. Discuss eligibility with your doctor.
Important caution
Lung cancer is serious but increasingly treatable when diagnosed early and typed accurately.
Never ignore a persistent cough or hemoptysis—early evaluation saves lives.
If you smoke, quitting and discussing screening are the most powerful steps you can take today.