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Lung Cancer

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Definition of lung cancer

  • Malignancy arising from lung tissue

 

Epidemiology of lung cancer

  • Commonest malignancy in western world
  • Commonest cause of death in men and women in  the UK
  • Approximately 38 000 new cases diagnosed annually in the UK
  • 90% are smoking-related

 

Types of lung cancer

  • Non- Small cell lung cancer (NSCLC)
    • Approximately 75-80% of all lung malignancy
    • Squamous cell carcinoma
      • Commonest primary lung malignancy
      • Associated with hypercalcaemia
      • Usually presents as a mass on CXR
    • Adenocarcinoma
      • Not necessarily associated with smoking
      • Can be primary or metastatic
    • Alveolar cell carcinoma
  •  Small cell lung cancer (SCLC)
    • Approximately 20-25%
    • Most aggressive
      • Frequent sites of metastases are liver, bone, adrenals and brain
    • Associated with syndrome of inappropriate ADH (SIADH)
    • Chemosensitive and radiosensitive

 
Rarer types of lung cancer

  • Carcinoid
    • 1% all tumours – 60% visible from bronchial tree
    • Vascular, tend to bleed
    • Originate from APUD
    • Only a small number lead to carcinoid syndrome
    • 5 year survival 90% with surgery
  • Mesothelioma (sometimes classified as a ‘lung cancer’)
    • Causes – Asbestos
    • M>F
    • Presentation: Pleuritic chest pain, Pleural effusion, Anorexia, night sweats
    • Treatment: Chemo/RT, treatment of pleural effusions

 

Risk factors for lung cancer

  • Smoking
  • Scarring
  • Asbestos
  • Air pollution including biofuels

 

Presentations of lung cancer

  • Local tumour effects
    • Persistent cough or change in usual cough
    • Haemoptysis
    • Chest pain
    • Shortness of breath
    • Hoarse voice – invasion of left recurrent laryngeal nerve
    • Unresolving pneumonia
    • Pleural effusion
    • Raised hemidiaphragm – phrenic nerve paralysis
  • Metastatic tumour effects
    • Lymphadenopathy
    • Bone pain/ pathological fracture
    • Neurology secondary to cerebral mets
    • Hypercalcaemia effects – bony mets
  • Paraneoplastic syndromes
    • Hypercalcaemia (NSCLC – especially squamous cell)
      • Due to parathyroid hormone related peptide (PTHrP)
    • SIADH (SCLC)
    • Cushing’s (SCLC)
      • Due to ectopic ACTH production
    • Gynaecomastia
    • Hypertrophic pulmonary osteo-arthropathy
      • More common in squamous and adeno
    • Lambert-Eaton Myaesthenic syndrome – LEMS (SCLC)
      • Proximal limb and trunk weakness. Associated with autonomic symptoms and hyporeflexia
    • Glomerulonephritis

 

 

Differential diagnosis of lung cancer (mass on CXR)

  • Metastases
  • Hamartoma
  • Granuloma (TB, sarcoid)
  • Abscess
  • Cyst
  • AV malformation
  • Skin tumour

 

Investigation of lung cancer

  • Blood
    • FBC, U&E, LFT, Ca, clotting
  • Sputum cytology
    • Good for SCLC and squamous
  • Urine
    • Protein (?membranous GN)
  • CXR
    • Can be normal. Will show location of lesion, secondary pneumonia, pleural effusion, rib destruction, mediastinal lymphadenopathy
  • Diagnostic pleural tap or FNA of lymph nodes
  • CT (contrast enhanced)
    • Shows local spread and secondaries
    • Include brain, liver and adrenals
  • PET
    • Good for imaging mediastinum, esp to see if enlarged node are malignant
  • Pulmonary function tests (for treatment)
    • FEV1<1.5 is a contraindication for surgical resection
  • Bronchoscopy
    •  Good for defining anatomy and taking biopsy
  • Percutaneous aspiration and biopsy (under CT guidance)
    • Good for getting a sample of a peripheral tumour not accessible using bronchoscopy. 25% chance of pneumothorax so contra-indicated if FEV1 < 1

 

Staging of lung cancer (TNM staging System)

  • Tumour (T)
    • T1 – Contained within the lung and is <3cm
      • T1a<2mc, T1b 2-3cm
    • T2 – Between 3 and 7cm across or has grown into the main bronchus >2cm below the carina or has invaded the visceral pleura or lobar collapse
      • T2 tumours that are 5cm or smaller are classed as T2a and those larger than 5cm are T2b
    • T3 (extrapulmonary) – larger than 7cm or has grown into one of the following structures:
      • Chest wall, pleura, diaphragm, pericardium, Main bronchus <2cm from carina
    • T4 (extrapulmonary) – into one of the following structures:
      • Mediastinum, large vessels, trachea, oesophagus, spine, laryngeal nerve

 

  • Nodes (N)
    • N0 – no nodes
    • N1 – nodes nearest the affected lung
      • NB – will be removed with pneumonectomy
    • N2 – Mediastinal nodes on same side
    • N3 – Nodes on other side or above clavicles

 

  • Metastases (M)
    • M0 – no mets
    • M1a – mets in both lungs or a malignant pleural effusion or pericardial effusion
    • M1b – mets elsewhere

 

Management of lung cancer

  • Surgery
    • Mainly for NSCLC
    • Curative only in T1M0N0 non-small cell disease
    • About 5-10% of cases.
    • Operative mortality in over-65s exceeds 5-year survival
    •  Contraindications
      • SVC obstruction
      • Tumour within 2cm of either main bronchus (as not enough resection margin for pneumonectomy)
      • FEV1<1.5
    • Survival improved with adjuvant chemo
      • For SCLC the median survival is 16 months. Full response rate in 40-50%, partial in a further 40%.
  •  Chemotheray
    • For SCLC

 

  • Radiotherapy
    • High dose radiotherapy can be curative in patients with slow-growing squamous carcinoma
    • Causes some (often asymptomatic) pulmonary fibrosis
    • Can use chemoradiotherapy for advanced disease
  • RT with palliative Intent
    • Can be used to treat haemoptysis, bone pain and SVC obstruction in the short term
      • Generally called CHART (continuous hyperfractioned RT)
    • Adjuvant chemo chemo-RT can extend median survival in non-small cell disease
    • Laser ablation, Interbronchial brachytherapy and bronchial stents can be used to treat occlusion of bronchi by tumour.
    • Other palliative treatments include:
      • Prednisolone to improve appetite
      • Morphine for pain
      • Regular laxatives
  • Treatment of oncological emergencies
    • Superior Vena Caval Obstruction (SVCO)
      • ABC approach
      • Steroids – Dexamethasone 8mg bd
      • Radiotherapy/ chemo to treat cause
      • Intra-luminal stents
    • Cord compression
      • Steroids – Dexamethasone 4mg qds
      • Radiotherapy
      • Surgical decompression
    • Hypercalcaemia
      • Isotonic saline hydration – 3L in 24 hours at least (250ml/hr)
        • Avoid overload. Can use furosemide to increase calcium excretion
      • Steroids
      • Bisphosphonates e.g. Pamidronate 30-60mg over 2 hours, Zolendronic acid 4mg over 2 hours. 

 

Complications of lung cancer

  • Tumour
    • Local
      • Recurrent laryngeal nerve palsy
      • Phrenic nerve palsy
      • Brachial plexus invasion
      • Horner’s syndrome
    • Distant
      • Mets
        • Brain, bone, liver
        • Adrenal symptoms (Addisons)
  • Endocrine
    • SIADH – small cell
      • Concentrated urine (Na >20mmol; osm > 500)
      • No hypovolaemia, oedema or diuretics
    • ACTH (Cushings) – small cell
    • PTH – squamous cell
      • Actually PTHRP
      • Can lead to hypercalcameia
  • Neurological
    • LEMS (pre-synampic calcium channel Abs)
    • Neuropathy (anti-Hu)
    • Cerebellar degeneration (anti-Yo or Purkinje)
  • Muscular
    • Polymyositis
    • Proximal myopathy
    • HPOA

 

Prognosis of lung cancer

  •  SCLC: untreated, the prognosis is 6 weeks
  • Others depend of type, stage and grade

 

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