What is Lung Cancer? Types and Stages of Lung Cancer

What is Lung Cancer Types and Stages of Lung Cancer

Lung cancer is a type of cancer that starts in the cells of the lungs. It can occur in the airways (small tubes) or the lung tissue.

Types of Lung Cancer

Non-Small Cell Lung Cancer (NSCLC)


Adenocarcinoma, the most common NSCLC, often originates in the outer parts of the lungs. Triggered by genetic mutations, particularly in the EGFR gene, these tumors tend to spread to lymph nodes and distant organs.

Squamous Cell Carcinoma:

Linked to heavy smoking, squamous cell carcinoma emerges from flat cells lining the airways. Genetic mutations, notably in TP53 and p16 genes, drive its formation, and local invasion is a common feature.

Large Cell Carcinoma:

Characterized by rapid growth and a lack of well-defined boundaries, large-cell carcinoma is associated with various genetic alterations. Its aggressive nature increases the likelihood of metastasis.

Small Cell Lung Cancer (SCLC)

Strongly correlated with tobacco smoking, SCLC is marked by rapid growth and early metastasis. Neuroendocrine features distinguish this subtype, making it one of the most aggressive forms of this condition.

Other Types

Carcinoid Tumours

Arising from neuroendocrine cells in the lungs, carcinoid tumors exhibit slow growth and are considered low-grade malignancies. Some may produce hormones, leading to specific clinical syndromes.

Adenosquamous Carcinoma

This subtype displays mixed characteristics of adenocarcinoma and squamous cell carcinoma. Its genetic complexity requires tailored treatment approaches.

Sarcomatoid Carcinoma

Originating from connective tissue cells in the lungs, sarcomatoid carcinoma is known for its aggressive growth and challenges in treatment due to diverse cellular features.

Stages of Lung Cancer:

Stage 0:

At this early stage, cancer is limited to the lung lining and has not invaded deeper lung tissues.

Stage I

Cancer is confined to the lung and has not spread to lymph nodes or other organs.

Stage II

Cancer has spread to nearby lymph nodes but not too distant organs.

Stage III

Cancer has advanced to nearby structures and lymph nodes.

Stage IV

At the most advanced stage, cancer has metastasized to distant organs.

Symptoms and First Signs of Lung Cancer:

Recognizing the symptoms and early signs is crucial for early detection and improved outcomes

●        Chest Pain:

●        Unintended Weight Loss:

●        Hemoptysis:

● Persistent Cough

Pathophysiology of Lung Cancer:

Lung cancer is a complex disease with various subtypes, but the general pathophysiology involves the uncontrolled growth of abnormal cells in the lungs.

Initiation and Carcinogenesis:

  • Exposure to carcinogens: The most common cause is long-term exposure to tobacco smoke, which contains numerous carcinogens. Other risk factors include exposure to radon gas, asbestos, air pollution, and a family history of lung cancer.
    • Genetic mutations: Carcinogens can induce genetic mutations in the normal cells of the lungs, leading to the initiation of cancer development.

Cellular Changes and Tumour Formation:

  • Transformation of normal cells: The genetic mutations lead to the transformation of normal lung cells into cancer cells.
    • Uncontrolled cell growth: The mutated cells lose their normal regulatory mechanisms, leading to uncontrolled proliferation.
    • Formation of tumors: As the cancer cells divide uncontrollably, they form masses or tumors within the lungs.

Invasion and Metastasis:

  • Invasion of surrounding tissues: Cancer cells can invade nearby tissues and structures, such as blood vessels and bronchi, as they grow and multiply.
    • Metastasis: Cancer cells can break away from the primary tumor and travel through the bloodstream or lymphatic system to other organs, forming secondary tumors (metastases). Common sites of metastasis for lung cancer include the brain, bones, liver, and adrenal glands.

Immune System Evasion:

  • Cancer cells may develop mechanisms to evade the immune system, allowing them to escape detection and destruction by the body’s natural defense mechanisms.


  • Tumor angiogenesis: Cancer cells release signals that stimulate the growth of new blood vessels (angiogenesis) to supply the growing tumor with nutrients and oxygen.

Pharmacotherapies of Lung Cancer:

Looking into how lung cancer is treated shows many ways doctors can help, using various methods.


  • Traditional cytotoxic drugs target rapidly dividing cells.
  • It was administered systemically to target cancer cells throughout the body.

Targeted Therapies:

  • Drugs are specifically designed to target specific molecular pathways.
  • EGFR inhibitors, ALK inhibitors, and other targeted agents tailored to specific genetic mutations.


  • Enhances the body’s immune response against cancer cells.
  • Checkpoint inhibitors like PD-1/PD-L1 inhibitors promote immune system activation.

Can Newly Invented Devices Like Hookah and Vaping Cause Lung Cancer?

Yes, Potential Risks Exist, while the long-term impacts are still under research, emerging evidence suggests that the use of hookah and vaping may pose risks for lung cancer. Inhaling the aerosols from these devices exposes the lungs to potentially harmful chemicals, contributing to cellular changes.

Surgical Interventions of Lung Cancer:

Surgical interventions play a pivotal role in the management of this condition.


A lung lobectomy involves removing one of the lobes of the lung. This procedure is used to treat cancer that is confined to a specific lobe of the lungs.


The surgical procedure in which an entire lung is removed. This procedure is mainly used to treat lung cancer when the affected lung cannot be effectively treated or preserved, after pneumonectomy, the remaining lung takes over the respiratory function.

Minimally Invasive Techniques:

  • Procedure: Utilises small incisions and specialized instruments.
  • Clinical Context: Enhances precision and reduces recovery time.

Prevention of Lung Cancer:

  • Smoking Cessation: The most effective preventive measure.
  • Environmental Awareness: Reducing exposure to air pollutants and occupational carcinogens.
  • Comprehensive Screening Programs: Regular screenings for high-risk individuals.
  • Early Intervention Strategies: Prompt treatment for pre-cancerous lesions or early-stage cancers.


In conclusion, this comprehensive exploration endeavors to shed light on the multifaceted nature of this condition. From its intricate pathophysiology to preventive strategies, each facet contributes to the broader narrative of understanding and managing this challenging condition. As we navigate this evolving landscape, guided by experts like Dr. Sharma, the vision is clear—a future where this condition is not just treatable but ultimately preventable, ensuring a world where everyone can breathe freely and without the shadow of this formidable disease.

In the realm of lung cancer research and treatment, experts like Dr. Satish Sharma play a pivotal role. As a distinguished medical oncologist and hematologist in Ranchi, Dr. Sharma’s contributions are instrumental in advancing our understanding of lung cancer. His dedication to patient care, research endeavors, and advocacy underscores the collaborative effort required to combat this formidable disease.


Q. What are the common types of lung cancer?

A. Common types include non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC), each with distinct characteristics.

Q. What are the risk factors for developing lung cancer?

A. Smoking, exposure to secondhand smoke, radon, asbestos, air pollution, family history, and genetic predisposition are common risk factors.

Q. How is lung cancer diagnosed?

A. Diagnosis typically involves imaging tests like CT scans, biopsies, and sometimes genetic testing to determine the type and stage of cancer.

Q. What are the stages of lung cancer?

A. Lung cancer staging ranges from stage 0 (earliest) to stage IV (most advanced), determining the extent of cancer spread and guiding treatment decisions.