Lung cancer

• Lung cancers are classified into two main categories: small cell(15-20% of total) or non-small cell(80-85%)carcinoma. Non-small cell can be further divided into squamous cell, adenocarcinoma, carcinoid tumor and large cell.
• Small cell carcinomas originate from neuroendocrine cells. Small cell carcinomas generally develop centrally near a main bronchus and have a strong association with smoking. They grow quickly and metastasize rapidly in comparison to non-small cell lung cancers.
• Risk factors for lung cancer:

  • Smoking
  • Asbestos exposure
  • Air pollution
  • Exposure to Radon gas
  • Exposure to ionizing radiation
• Signs and symptoms of lung cancer:

  • Chronic cough
  • Hemoptysis
  • Wheezing
  • Chest and bone pain
  • Chest infections
  • Nail clubbing
  • Unexplained weight loss
  • Shortness of breath
  • Raspy, hoarse voice
  • Dysphagia
• Lung tumors can compress the phrenic nerve, leading to paralysis of the ipsilateral hemidiaphragm, which can cause further respiratory compromise. Compression of the recurrent laryngeal nerve can present with hoarse voice. Compression of the superior vena cava can cause facial swelling, prominent facial and/or upper limb veins and respiratory compromise (Pemberton's sign).
• Paraneoplastic syndromes of lung cancer:

  • Squamous cell lung cancers can produce PTHrP, which can mimic the function of PTH, leading to clinical features of hypercalcemia.
  • Adenocarcinoma can cause hypertrophic osteoarthropathy that can present with clubbing, joint pain, and bone pain.
  • Small cell lung cancers can produce ADH, leading to SIADH, and in turn hyponatremia. They can also produce ACTH, leading to Cushing's syndrome
• Differential diagnosis for lung cancer:

  • Pneumonia
  • Tuberculosis
  • Pulmonary embolism
  • Heart failure
• Investigations for lung cancer:

  • Chest X-ray
  • CT
  • Transbronchial biopsy (if tumor is within the lumen)
  • Ultrasound guided endoscopic biopsy (If tumor is outside the lumen)
  • Transthoracic CT guided biopsy (if tumor is peripheral)
• Features of adenocarcinomas:

  • Peripheral
  • Cuboidal/columnar cells
  • Form acinus glands
  • Papillary structures
  • May line alveoli
  • Can produce mucin
• Features of small cell carcinoma:

  • Very cellular
  • Small nuclei
  • Little cytoplasm
  • Nuclear molding
  • Often necrosis and lots of mitoses
• Effects of lung cancer spread in the lung:

  • Necrosis
  • Ulceration leading to hemoptysis
  • Infection leading to abscess formation
  • Bronchial obstruction leading to collapse and consolidation
• Effects of lung cancer spread in the thorax:

  • Pleural or pericardial effusions
  • SVC obstruction
  • Dysphagia
  • Vocal cord palsy
  • Diaphragm palsy
• Management of lung cancer:

  • Chemotherapy
  • Radiotherapy
  • Surgical resection (lobectomy, pneumonectomy, wedge resection, sleeve resection) - extent is determined by lung function testing
• Sites of lung cancer metastasis:

  • Other lung
  • Liver
  • Adrenals
  • Bone
  • Brain
• • Squamous cell carcinomas also develop centrally and have a strong association with smoking.
  • Adenocarcinomas develop peripherally in a bronchial or alveolar wall, also associated with smoking and more common in women.
  • Large cell carcinomas are found throughout the lung, centrally or peripherally.
• • Horner's syndrome is a rare condition classified by partial ptosis, miosis and facial anhidrosis.
  • It is usually caused due to a disruption of the sympathetic nervous chain.
  • In the case of lung cancer, Horner's syndrome is usually due to compression of the cervical sympathetic chain by a non-small cell tumor in the apical lobe, termed a Pancoast tumor.
• Histological features of squamous cell carcinoma:

  • Location: Central
  • Angulate cells
  • Eosinophilic
  • Keratinization
  • Intercellular bridges
  • Keratin pearls