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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