Understanding Lung Cancer: A Comprehensive Overview

Understanding Lung Cancer: A Comprehensive Overview

1. Introduction to Lung Cancer

Lung cancer is characterized by the abnormal, uncontrolled growth of cells in the lungs. It is the leading cause of cancer-related deaths worldwide, with 2.2 million new cases and 1.8 million deaths reported in 2020. In India, lung cancer accounts for approximately 72,510 new cases annually and 66,279 deaths, representing 5.8% of all cancer cases and 7.8% of cancer deaths.

2. Risk Factors for Lung Cancer

• Cigarette smoking is the primary cause of lung cancer.

• Use of other tobacco products significantly increases the risk.

• Secondhand smoke exposure contributes to the incidence of lung cancer.

• Asbestos exposure is a known occupational hazard linked to lung cancer.

• Radon, a naturally occurring radioactive gas, is a risk factor as well.

• Certain workplace hazards may increase susceptibility to lung cancer.

• A personal or family history of lung disease can elevate risk.

• Previous radiation therapy targeting the chest area may predispose individuals to lung cancer.

3. Types of Lung Cancer

Lung cancer is primarily classified into two main types: Non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC).

• Non-small cell lung cancer (NSCLC): NSCLC is the more common form, accounting for around 85% of all lung cancers. It originates in the cells lining the airways and lung tissue and is slower growing compared to SCLC. NSCLC may remain asymptomatic in the early stages and is often diagnosed in later stages when the cancer has metastasized. As it progresses, it may produce symptoms like a persistent or dry cough, coughing up blood in phlegm, chest pain, shortness of breath, unexpected weight loss, or weakness.

  • Adenocarcinoma: Found in mucosal gland cells that line the organs. It is the most common form of primary carcinoma of the lung and is often found in areas of scars or inflammation.

  • Squamous cell carcinoma of the lung (SCCL): Originates in squamous cells in the airways, mostly in the central parts of the lungs. It is closely linked with smoking.

  • Large cell lung carcinoma (LCLC): Characterized by large, undifferentiated epithelial cells that lack the features of squamous or glandular differentiation. Known for rapid growth and metastasis, LCLC typically appears as large masses in the periphery of the lungs on imaging studies.

• Small cell lung cancer (SCLC): SCLC is less frequent (approximately 10-15% of lung cancers) compared to NSCLC but is very aggressive and fast-growing. It usually affects smokers. It gets its name because, when its cancer cells are examined under a microscope, they are smaller and oval-shaped. It generally originates in the central airways of the lungs.

4. Diagnosis of Lung Cancer

A variety of diagnostic tools are used to detect lung cancer, including:

• Chest X-rays: This is the initial tool to identify abnormal masses but not for definitive diagnosis as it cannot differentiate between benign and malignant masses.

• CT scans: These provide detailed images of the lungs, aiding in determining the size, location, and spread of cancers in the tissues. CT scans are also useful for performing CT-guided biopsies of tumors.

• PET-CT scans: These assess the metabolic activity of cancerous cells and provide more details of primary and metastatic masses, further aiding in the staging of cancers.

• MRI: This is used for detailed imaging, especially for brain metastases and soft tissues.

• Bronchoscopy: This allows for direct visualization of the tissue and helps in obtaining transbronchial lung biopsies (TBLB). It is an invasive procedure in which a specialized tube (bronchoscope) is passed into the airways through the mouth.

• Mediastinoscopy: This is performed by making a small incision at the base of the neck through which a mediastinoscope is passed into the mediastinal cavity to obtain biopsies of lymph nodes. It is useful for staging lung cancer.

• Transthoracic Needle Biopsy: Also known as a lung needle biopsy, this procedure is used to obtain tissue samples for diagnosis and staging.

• Sputum Cytology: This is a cost-effective and non-invasive test for detecting lung cancer, especially in elderly people who cannot tolerate invasive procedures. Collected sputum samples are examined microscopically to analyze mucus for cancer cells.

• Endobronchial Ultrasound (EBUS): This minimally invasive procedure uses a bronchoscope containing an ultrasound probe to examine and sample the airways. It can detect lung masses, measure their size, and is very useful for obtaining samples for histopathological examination to aid in diagnosis and staging.

• Tumor Markers: These are helpful in diagnosing and differentiating lung cancers. Common tumor markers for lung cancers include:

  • Carcinoembryonic Antigen (CEA): A protein that elevates in cancers, including lung cancers, especially adenocarcinoma. It is useful in detecting cancers and monitoring the effectiveness of treatment and recurrence.

  • Cytokeratin 19 Fragment (CYFRA 21-1): A fragment of cytokeratin 19 found in epithelial cells that elevates in NSCLC.

  • Squamous Cell Carcinoma Antigen (SCC): A protein found in squamous cell carcinoma that is elevated in squamous cell carcinoma.

  • Other tumor markers that may increase in lung cancers include neuron-specific enolase (NSE) and pro-gastrin-releasing peptide (ProGRP).

5. Staging of Lung Cancer

After diagnosis, lung cancer is staged to determine the extent of disease and treatment options by analyzing imaging studies along with histopathological examination. Staging helps in selecting appropriate treatment modalities based on cancer progression.

6. Management of Lung Cancer

A multidisciplinary approach is essential in managing lung cancer, which may include:

• Surgery: Surgery is considered primarily in early non-small cell lung cancers. Depending on the location, size, and type of cancer, it can be done by:

  • Wedge Resection: Removing a small wedge-shaped section along with a margin of healthy tissue.

  • Segmentectomy: Removing a larger portion of the lung but not the whole segment.

  • Lobectomy: Removing an entire lobe.

  • Pneumonectomy: Removing an entire lung on one side.

  • Sleeve Lobectomy: Removing part of the lung along with the main bronchus, with the ends rejoined.

• Chemotherapy: Used to kill cancer cells, it can be done with other treatment options like before surgery to shrink the size of the mass and after surgery to kill remaining cancer cells. It can also be done along with immunotherapy or before radiotherapy.

• Immunotherapy: Enhances the body's immune response against cancer, aiming to strengthen the immune response to identify and kill cancer cells.

• Radiotherapy: Targets tumor cells with high-energy radiation to kill cancer cells or shrink the size of the tumor.

• Targeted Therapy: Focuses on specific cancer cell characteristics like identifying and attacking molecular targets or gene mutations rather than attacking all cells.

7. Prognosis of Lung Cancer

• The overall 5-year survival rate for lung cancer is around 25%.

• Early-stage NSCLC (stage 1-2) has a significantly better 5-year survival rate of 64%.

• In advanced stages (3-4), the survival rate drops to around 5%.

• Younger patients generally have better survival rates compared to older patients.

8. Case Presentation

An illustrative case of an 86-year-old patient presenting with symptoms of cough, shortness of breath, generalized weakness, and chest pain for one month.

• Past Medical History: Known case of COPD on irregular treatment, heavy smoker up to the age of 40 years, occasional alcohol consumer.

• General Physical Examination: Vitals were stable, chest auscultation revealed decreased air entry on the left side of the chest along with ronchi.

• Chest X-Ray: Revealed a mass in the left upper zone larger than 4 cm, raising suspicion of large cell lung cancer.

  
  

  

  Image 1. Showing Mass in left Uppar zone of lung which is larger in size raising suspicion of large cell lung cancer.

  
  

• CT Scan: Confirmed the diagnosis of large cell lung cancer.

  
  

  

  Image 2. CT Image of same patient Confirmed the diagnosis of large cell lung cancer.

  
  

• After revealing the diagnosis and poor prognosis to the attendants and thorough discussion, further invasive procedures were deferred due to the patient's advanced age and were also denied by the attendants.

9. Challenges in Management

Due to the advanced age of the patient, standard invasive diagnostic procedures and treatment options such as surgery or chemotherapy were not suitable.

10. Personalized Ayurvedic Treatment

In response to the patient's advanced age and overall health condition, a personalized Ayurvedic treatment plan was implemented. The patient demonstrated survival for 7 additional months, highlighting a potential avenue for supportive care.

11. Conclusion

Understanding lung cancer involves recognizing risk factors, types, diagnostic methods, staging, management options, and prognosis. The significance of individualized treatment strategies is emphasized, especially in older patients with complex health needs. Ongoing awareness and education about lung cancer can help improve early detection and treatment outcomes.