Lung cancer

The Function of the Lungs and Complications Associated with Lung Cancer

The lungs are a pair of vital organs located in the chest, responsible for the crucial task of exchanging oxygen and carbon dioxide between the body and the environment. Every breath we take delivers oxygen to the bloodstream and removes waste gases like carbon dioxide. Besides gas exchange, the lungs also help maintain pH balance, protect against inhaled pathogens and toxins, and assist in regulating blood pressure by converting angiotensin I to angiotensin II. Any disease that interferes with normal lung function can seriously impair life quality. Lung cancer disrupts this function, leading to complications such as respiratory failure, systemic hypoxia, recurrent infections, and even the spread of malignancy to distant organs.

Lung cancer arises from the tissues of the lung, typically from cells lining the air passages. According to medical consensus, genetic mutations in these cells cause them to multiply uncontrollably and form malignant tumours. Although lung cancer may not always be prevalent in every demographic, it is still among the top causes of cancer-related deaths worldwide. This is particularly true due to late diagnosis, rapid progression, and strong correlations with environmental and lifestyle factors. Education and awareness—especially about the causes such as smoking and environmental pollutants—are essential to mitigate the risk. Raising public consciousness through campaigns, health checkups, and targeted policies helps with early detection and management.

Categories Associated With Primary And Secondary Lung Tumours

Lung tumours are generally classified into Primary and Secondary types:

Primary Lung Cancer:

This originates directly in the lung tissue. The two main categories include:

  • Non-Small Cell Lung Cancer (NSCLC): The most common type, accounting for around 85% of all lung cancers. Subtypes include adenocarcinoma, squamous cell carcinoma, and large cell carcinoma.
  • Small Cell Lung Cancer (SCLC): Known for its aggressive nature, this type spreads more rapidly and is more responsive to chemotherapy initially, but has a poorer overall prognosis.

Secondary (Metastatic) Lung Cancer:

This arises when cancer cells from another part of the body (e.g., breast, colon, prostate) spread to the lungs. Metastatic tumours are more common than primary lung cancer in patients with advanced systemic cancers.

Causes and Risk Factors for Lung Cancer

The transformation of healthy lung cells into malignant ones typically results from cumulative exposure to harmful substances or genetic predispositions. Common causes include:

  • Tobacco Smoking: The most significant risk factor, responsible for nearly 85% of all lung cancers. Cigarette smoke contains over 70 known carcinogens.
  • Secondhand Smoke: Non-smokers exposed regularly to smoke are at increased risk.
  • Radon Gas Exposure: Naturally occurring radioactive gas can accumulate in poorly ventilated homes and increase cancer risk.
  • Asbestos Exposure: Occupational exposure, especially in construction and shipbuilding industries, is associated with mesothelioma and lung cancer.
  • Air Pollution: Long-term exposure to fine particulate matter and industrial pollutants significantly raises the risk.
  • Family History and Genetic Predisposition: A genetic mutation or inherited susceptibility can increase one’s chance of developing lung cancer.
  • Prior Radiation Therapy: Patients who have undergone chest radiation for other cancers may have an elevated risk.

Signs and Symptoms of Lung Cancer

Lung cancer often presents without clear symptoms in its early stages, making early detection difficult. Common signs include:

  • Persistent cough or changes in a chronic cough
  • Coughing up blood (hemoptysis)
  • Chest pain that worsens with deep breathing, coughing, or laughing
  • Hoarseness
  • Unexplained weight loss
  • Fatigue or general weakness
  • Shortness of breath
  • Recurring infections like pneumonia or bronchitis
  • Bone pain (in metastatic disease)
  • Neurological symptoms occur if cancer spreads to the brain

Diagnosis of Lung Cancer

Diagnosis involves multiple tests to confirm malignancy and assess its spread:

  • Medical History and Physical Exam
  • Imaging Studies: Chest X-ray, CT scan, PET scan, or MRI to identify lung masses and evaluate for metastasis.
  • Sputum Cytology: Microscopic examination of mucus coughed up from the lungs for cancer cells.
  • Bronchoscopy and Biopsy: A flexible tube is inserted into the lungs to extract tissue samples.
  • Needle Biopsy: Fine needle aspiration under CT or ultrasound guidance.
  • Molecular and Genetic Testing: Determines specific mutations (e.g., EGFR, ALK, KRAS) for targeted therapy suitability.
  • Staging Workup: Essential for selecting a treatment plan and includes bone scans and brain imaging to check for metastases.

Best Treatment for Lung Cancer

Lung cancer treatment depends on the type, stage, genetic markers, and the patient’s overall health. Divided into:

A. Traditional Treatments

1. Surgical Procedures

  • Lobectomy: Removal of one lobe of the lung; standard for early-stage NSCLC.
  • Pneumonectomy: Removal of an entire lung, reserved for large or centrally located tumours.
  • Segmentectomy/Wedge Resection: For smaller tumours or patients with limited lung function.

2. Radiation Therapy

  • External Beam Radiation Therapy (EBRT): Targets tumours with high-energy beams from outside the body.
  • Stereotactic Body Radiotherapy (SBRT): High-precision radiation used in small tumours, often as an alternative to surgery.

3. Chemotherapy

  • Systemic drugs are administered intravenously or orally to destroy cancer cells throughout the body. Used pre- or post-surgery or for advanced-stage disease.
  • Common agents include cisplatin, carboplatin, paclitaxel, and docetaxel.

B. Advanced Treatments for Lung Cancer

1. Microinvasive Therapies and Surgeries

  • Radiofrequency Ablation (RFA): Delivers heat via a probe to destroy tumour tissue.
  • Microwave Ablation (MWA): Similar to RFA but uses microwave energy.
  • Cryoablation: Uses extreme cold to freeze and kill cancer cells with minimal damage to nearby tissues.

2. Targeted Therapies

These therapies are directed at specific genetic mutations or proteins in cancer cells.

  • EGFR Inhibitors: (e.g., Erlotinib, Afatinib) for EGFR-mutant NSCLC.
  • ALK Inhibitors: (e.g., Crizotinib, Alectinib) for ALK-positive patients.
  • ROS1 and BRAF Targeted Agents: For patients with these rare mutations.

3. Targeted Radiation Therapy

  • Brachytherapy: Radioactive seeds implanted near or into tumours to deliver localised radiation.
  • Radioembolization: Mostly used for metastasis to the liver from lung tumours.

4. Immunotherapy and Stem Cell Therapies

  • Immune Checkpoint Inhibitors: Drugs like Nivolumab and Pembrolizumab activate T-cells to destroy cancer cells.
  • CAR-T Cell Therapy: Under investigation for solid tumours like lung cancer.
  • These therapies are revolutionising treatment by offering fewer side effects and prolonged survival.

Prevention and Lifestyle Management

Effective prevention strategies focus on reducing exposure to known carcinogens:

  • No smoking and complete cessation for smokers
  • Avoiding secondhand smoke
  • Regular testing for radon in homes
  • Workplace safety for asbestos and industrial pollutants
  • A healthy diet rich in antioxidants
  • Regular physical activity and maintaining a healthy weight
  • Lung screenings (low-dose CT) for high-risk individuals, such as long-term smokers

Prognosis and Survival Rates.

When it comes to prognosing, options available depend greatly on the stage at diagnosis, general well-being, relations between treatments and recovery, and overall health condition. The American Cancer Society states that:

Approximately 65 per cent is the five-year survival rate associated with the localised stage

45 percent

Increased relocation stage

35% projected rate contingent on aid from adjacent lymph nodes

8% survival estimate for distant (metastatic) parameters

Improvement in outcomes hinges on early detection through screening programs, particularly for high-risk populations such as smokers.

Conclusion

Lung cancer is a leading cause of cancer mortality due to its aggressive nature and late detection. Understanding its causative factors and utilising early detection methods are essential in improving survival rates. Innovations in targeted therapy, immunotherapy, and minimally invasive surgeries are promising developments that offer new hope for patients. Ongoing education, prevention, and systematic screening are fundamental in the battle against this formidable disease.