Lung Cancer

Lung cancer is a malignant tumor that develops in the lungs. It can be classified as:

• Primary lung cancer: originating within the lung.
• Metastatic lung cancer: cancer that has spread to the lungs from another organ through blood vessels or lymphatic channels.

Based on the size and appearance of cancer cells under the microscope, lung cancer is divided into non–small cell lung cancer (NSCLC) and small cell lung cancer (SCLC).

• NSCLC includes squamous cell carcinoma, adenocarcinoma, and large cell carcinoma. When diagnosed early, NSCLC may be cured with surgical treatment.
• SCLC grows rapidly and tends to spread throughout the body, but it often responds well to chemotherapy and radiation therapy.

Respiratory symptoms

• Cough: The most common symptom, reported in about 75% of lung cancer patients. Smokers may dismiss persistent cough as smoking-related, delaying diagnosis.
• Hemoptysis (blood-tinged sputum): Coughing up blood or blood-streaked sputum may indicate lung cancer, though not exclusively. Lung bleeding typically appears as bright red sputum.
• Shortness of breath: Experienced by nearly half of patients. It may result from tumor growth, fluid buildup in the pleural cavity, or airway obstruction.
• Chest pain: Reported in about one-third of patients. Pain may occur when the tumor invades the pleura or chest wall, sometimes sharp and intermittent, later becoming persistent and dull. Pain can also result from rib metastasis or pleural invasion.
• Hoarseness: When lymph node metastasis compresses the nerve controlling the vocal cords, hoarseness may develop.

Other local or systemic symptoms

• Facial or arm swelling: Compression of the superior vena cava by the tumor can block venous return, causing swelling of the face, neck, and upper extremities. This condition, called superior vena cava syndrome, may worsen when lying down or leaning forward.
• Bone pain or fractures: Bone metastases may cause severe pain and pathologic fractures.
• Enlarged lymph nodes: Cervical or supraclavicular lymph nodes may be palpable.
• Systemic symptoms: Unintentional weight loss, loss of appetite, nausea, vomiting, and fatigue.

• Smoking: The most significant risk factor. Smokers are 15–80 times more likely to develop lung cancer than non-smokers.
• Carcinogen exposure: Radionuclides, air pollution, asbestos, arsenic, and radon gas are known contributors.
• Underlying lung disease: Conditions such as chronic obstructive pulmonary disease (COPD), tuberculosis, and silicosis increase risk.
• Family history: Having a first-degree relative with lung cancer increases risk two- to threefold.

• Quit smoking: About 90% of lung cancers can be prevented by avoiding tobacco. Risk rises with smoking intensity and duration. Even after quitting, risk remains elevated for up to 20 years, underscoring the importance of early cessation.
• Reduce exposure to risk factors: Avoid secondhand smoke, minimize occupational exposures (e.g., asbestos, arsenic, chromium), and reduce contact with radioactive substances such as radon or uranium.
• Balanced diet: No specific foods are proven to prevent lung cancer. Maintaining a balanced diet with fresh fruits and vegetables (e.g., tomatoes, cabbage, and broccoli) supports overall health. Excessive intake of micronutrient supplements for prevention is not recommended.