Makindo Medical Notes

Related Subjects: |Bronchogenic Lung Cancer |Hypercalcaemia |Oncological emergencies |Malignant Hyperparathyroidism due to PTHrP |Lambert-Eaton syndrome (LEMS) |Superior Vena Caval Obstruction syndrome |Syndrome of Inappropriate ADH (SIADH) secretion |Cushing's Syndrome due to Ectopic ACTH

Lung cancer is classified into two main categories: small cell lung cancer (SCLC), which accounts for approximately 20%, and non-small cell lung cancer (NSCLC), comprising the remaining 80%. Notably, about 90% of lung cancer patients are either smokers or ex-smokers, highlighting the significant link between tobacco use and the development of this disease.

About

• Lung cancer is the most prevalent malignancy in developed countries, with over 40,000 new cases diagnosed annually in the UK alone.
• There has been a rising incidence of lung cancer among females, attributed to increased smoking rates and changing lifestyle factors.
• Early detection and treatment are critical, as lung cancer often presents at an advanced stage.

Aetiology

• 85-90% of lung cancer cases are related to smoking, particularly linked to squamous cell and small-cell lung cancers.
• Other significant risk factors include occupational exposure to hazardous substances such as asbestos, arsenic, nickel, silicosis, chromium, and radon gas.
• The risk of developing lung cancer is heightened in individuals with pre-existing conditions like pulmonary fibrosis, dermatomyositis, and idiopathic pulmonary fibrosis.

Histology and Prognosis: Types of Lung Cancer

Clinical Presentation

• Common symptoms include persistent cough, sputum production, hemoptysis (coughing up blood), chest pain, and dyspnea (shortness of breath).
• In more advanced stages, symptoms may progress to significant weight loss, persistent hoarseness, and signs of metastasis, such as bone pain or neurological deficits.
• Paraneoplastic syndromes associated with lung cancer may include Cushing’s syndrome, syndrome of inappropriate antidiuretic hormone secretion (SIADH), hypercalcemia, and Lambert-Eaton myasthenic syndrome.

Investigations

• Initial investigations typically include a full blood count (FBC), urea and electrolytes (U&E), and calcium levels to assess for complications like SIADH or hypercalcemia.
• Imaging studies such as chest X-rays (CXR) are employed to identify masses, while CT scans provide detailed staging, including assessment of the chest, liver, adrenal glands, and brain if clinically indicated.
• Tissue diagnosis is crucial and can be achieved via bronchoscopy, needle biopsy, or mediastinoscopy, tailored to the tumor's location.
• Additional staging with PET-CT scans is particularly valuable for NSCLC to evaluate metabolic activity and distant spread.

Staging (NSCLC)

Management

• A multidisciplinary team approach is essential, involving specialists from oncology, pulmonology, and surgical disciplines.
• For stages I to IIIA:
  • Surgical resection is the primary treatment option, particularly for stage I and II tumors that are localized and operable.
  • Lobectomy (removal of a lobe) is commonly performed, though wedge resection (removal of a small section) may be an option in some cases.
  • Adjuvant chemotherapy and/or radiotherapy may be recommended post-surgery to reduce recurrence risk, especially in higher-stage tumors.
• For stages IIIB-IV or inoperable cases:
  • Systemic therapies such as chemotherapy are the mainstay of treatment, often combined with targeted biological therapies and/or immunotherapy.
  • Radiation therapy may also be employed for symptom management or in combination with other treatments.

Criteria for Surgical Selection

• Tumor Stage: Patients with early-stage NSCLC (stage I to IIIA) are generally considered for surgical intervention.
• Tumor Size and Location: Tumors must be resectable, with careful evaluation of size and proximity to major structures (e.g., blood vessels, airways).
• Patient Fitness: Candidates must have adequate pulmonary function and overall health to withstand surgery; performance status is often assessed using the Eastern Cooperative Oncology Group (ECOG) scale.
• Absence of Metastasis: Surgery is typically contraindicated if there is evidence of distant metastasis (stage IV) or significant nodal involvement.
• Multidisciplinary Assessment: A thorough evaluation by a multidisciplinary team helps determine the best approach for individual cases, considering all treatment options and patient preferences.

Newer Treatments and Developments

• Low-dose CT screening is recommended for high-risk individuals, as it can lead to earlier detection and improved outcomes.
• Targeted therapies, including EGFR inhibitors (e.g., gefitinib) and ALK inhibitors, have shown promise in treating specific subtypes of NSCLC.
• Immunotherapies, such as checkpoint inhibitors (e.g., pembrolizumab, nivolumab), are being increasingly utilized to enhance the body's immune response against cancer cells.

Comparison of Small Cell and Non-Small Cell Lung Cancer