Lung cancer is a malignancy that originates in the lungs, particularly in the cells lining the air passages. It is one of the most common and deadly cancers globally. Lung cancer is primarily classified into two main categories: small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC).

Types:

• Non-Small Cell Lung Cancer (NSCLC): Includes adenocarcinoma, squamous cell carcinoma, and large cell carcinoma. NSCLC accounts for approximately 85% of lung cancers.
• Small Cell Lung Cancer (SCLC): More aggressive and tends to spread quickly, often found in heavy smokers.

Risk Factors:

• Smoking: The leading cause, with both active and passive exposure increasing risk.
• Radon Gas Exposure: Naturally occurring gas that can accumulate in homes and buildings.
• Exposure to Carcinogens: Such as asbestos, arsenic, and certain air pollutants.

Symptoms:

• Persistent cough that does not go away.
• Chest pain, especially with deep breaths or coughing.
• Hoarseness and wheezing.
• Unexplained weight loss and loss of appetite.
• Back pain

Investigation:

• Chest X-ray and CT Scan: Often used as first steps to detect abnormalities.
• Biopsy: Confirmatory test where a sample of the lung tissue is examined.
• Bronchoscopy: A camera is used to view the lung airways and take tissue samples.
• PET Scan: To check if the cancer has spread to other parts of the body.

Treatment Options:

• Surgery: Removal of the tumor, usually for early-stage NSCLC.
• Radiation Therapy: Used to target and kill cancer cells in early stage 
• Chemotherapy: Standard treatment for both NSCLC and SCLC.
• Targeted Therapy: Drugs that specifically target cancer cell metastatic stage 
• Immunotherapy: Helps the immune system fight cancer cells, especially effective in advanced cases.

Prognosis:
Lung cancer prognosis depends on the type, stage, and patient health. Early detection can improve outcomes, but late-stage lung cancer has a generally poor prognosis. Survival rates have improved with advancements in targeted therapy and immunotherapy.