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Medicine year 3 ANNA > Lung Cancer > Flashcards

Lung Cancer Flashcards

1
Q

Define Lambert-Eaton myasthenic syndrome (LEMNs)

A

Define:

  • Rare autoimmune disorder of the NMJ – antibodies against voltage-gated Ca2+ channels –> impairs influx of Ca2+ into presynaptic terminal –> thus inhibiting vesicular release of acetylcholine
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2
Q

What causes LEMS and what conditions is it associated with?

A
  • LEMS can occur as a para-neoplastic disorder in association with cancer i.e. CA-LEMS
    • N.B. LEMS can also occur as part of a generalised autoimmune state i.e. NCA-LEMS
  • CA-LEMS is often associated with SCC (small cell carcinoma) of the lung
  • > 40% of LEMS pts have underlying cancer (normally SCC lung)
  • SCC cells have high [voltage-gated Ca2+ channels] –> presumed that this triggers antibodies against the channels
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3
Q

What are the common features of LEMS?

A
  • Proximal muscle weakness (starts in legs)
  • Dry mouth ‘metallic taste’
  • Impotence (65% of men)
  • Dysphagia
  • Hyporeflexia or areflexia
  • Dysarthria (common but often occurs late in disease)
  • Ptosis (late symptom - whereas early in myasthenia gravis)
  • Diplopia (late symptom)
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4
Q

What are the 4 risk factors for LEMS?

A
  1. Hx of Cancer (especially small cell lung)
  2. Smoking
  3. Co-existing autoimmune condition
  4. FHx of autoimmune
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5
Q

What is the main test for LEMS?

A

Nerve conduction studies

  • Initially muscle action potential amplitude is low
  • After 10 seconds of exercise –> the same muscle shows significant increase in amplitude
  • I.e. muscle weakness is improved on exercise
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6
Q

How do you treat LEMS?

A
  1. Treat underlying cancer
  2. Amifampridine +/- Pyridostigmeine:
    • Amifampridine:
      • Use: treat myasthenic syndromes and LEMS
      • MoA: K+ channel antagonist which ↑ AP duration at nerve terminals –> thus Ca2+ channels can be open for longer –> ↑ vesicular ACh release
    • Pyridostigmeine:
      • Use: myasthenia gravis (may improve dry mouth/taste symptoms in LEMS)
      • MoA: inhibits acetylcholinesterase in the synaptic cleft –> ↑ ACh in synapse
      • Don’t use in intestinal or urinary obstruction
  3. IV immunoglobulin therapy
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7
Q

What calculator can be used for the probability of a nodule on CT being cancer?

A

Brock calculator

  • “estimates the probability that the lung nodule you describe in the calculator will be diagnosed with cancer within an 2-4yr follow up period”
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8
Q

Lung Cancer - Biostatistics:

  1. Is Lung cancer the 1st, 2nd or 3rd most diagnosed cancer in the UK?
  2. What is the >5yr survival of pts with lung cancer?
A
  1. Lung cancer is 2nd most diagnosed cancer in the UK (after breast)
  2. <10% of lung cancer pts survive for >5yrs
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9
Q

What are the risk factors for Lung cancer?

A
  1. Smoking (accounts for 95% of cases)
  2. Ionising radiation
  3. Asbestos
  4. Fibrosing alveolitis (I.e. IPF)
  5. Industrial chemicals; arsenic, chromium, nickel
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10
Q

What are the types/classifications of lung cancer?

A

Primary:

  • Small cell (~20%)
  • Non-small cell (~80%):
    • Squamous (~35%)
    • Adenocarcinoma {~30%)
    • Large cell (~10%)
    • Other (5%)

Secondary metastasis:

  • Breast, kidney, bladder, testis
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11
Q

Name a lung cancer common to the pleura - and a common cause.

A

Mesothelioma - can be caused by asbestos exposure

  • Image shows multieple pleural plaques suggestive of exposure to asbestos (not mesothelioma)
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12
Q

What are the features of the following types of Non-small cell lung cancer?

(where in the lungs is it located, what features are the commonly associated with)

  1. Squamous
  2. Adenocarcinoma
  3. Large cell
A
  1. Squamous​​
    • Typically central
    • Associated with parathyroid hormone-related protein (PTHrP) secretion → hypercalcaemia
    • Clubbing (strongly associated)
    • Hypertrophic pulmonary osteoarthropathy (HPOA) - clubbing + periostitis of small hand joints and distal expansion of long bones
    • Ectopic TSH –> hyperthyroidism
  2. Adenocarcinoma
    • Typically peripheral​​
    • HPOA
    • Most common type of lung cancer in non-smokers
  3. Large cell
    • ​​Typically peripheral
    • Poor prognosis
    • May secrete β-hCG (producing false positive pregnancy test)
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13
Q

What are some common signs/symtpoms of lung cancer?

A
  • Cough / haemoptysis
  • Chest pain
  • SoB
  • Weight loss
  • Lymphadenopathy
  • CXR - focal opacity, may be present with pleural effusion (may need CT to see carcinoma)
  • Stridor (usually inspiratory, high-pitch)
  • Hoarse voice - if tumour compresses recurrent laryngeal nerve e.g. Pancoast tumour
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14
Q

What are some features of small cell lung cancer, including features caused by hormone secretion?

A

Small Cell:

  • Usually central
  • Ectopic ADH secretion –> SIADH –> Hyponatremia
  • Ectropic ACTH secretion –> Cushing’s syndrome (hypertension, hyperglycaemia, hypokalemia, alkalosis and muscle weakness)
  • Lambert-Eaton syndrome (LEMS)
  • Anti-Hu antibodies - antigens released by tumour cause an immune response consisting of anti-hu antivodies which target nervous system causing anti-hu encephalitis e.g. vertigo, nystagmus
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15
Q

What are 3 complications of lung cancer?

A
  1. Pancoast Syndrome:
    • Pain / weakness ipsilateral arm - tumour can impose on brachial plexus
    • Hoarse voice + bovine cough - tumour compressing recurrent laryngeal nerve
    • Horner’s syndrome - miosis (constricted pupil), ptosis, sunken eye (enopthalmos), unilateral anhidrosis
    • Carcinoma at apex –> can protrude into supraclavicular fossa causing loss of recess
  2. Superior vena caval obstruction:
    • Prevents venous return from head, upper mediastinum + arms
    • Facial + hand swelling (worse in mornings)
    • Headaches
  3. Metastases:
    • Cutaneous mets e.g. large skin mass on hard palate
    • Liver mets - jaundice
    • Adrenal mets - diabetes secondary to hypercortisolism
    • Brain mets - can precipitate a haemorrhagic stroke
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16
Q

What investigations might you do in Lung Cancer?

A
  • CXR / CT scan
  • Fibre-optic bronchoscopy - can inspect large airways
  • Percutaneous needle biopsy - useful to determine cell type
  • Nodal biopsy
  • Mediastinoscopy - to visualise mediastinal contents and facilitate lymph node / mass biopsy
  • LFTs:
    • Deranged in liver mets
  • U+Es:
    • Determine renal function for medication or scans with contrast
  • TFTs:
    • Non small cell squamous carcinoma can cause hyperthyroidism
17
Q

How is Lung Cancer treated?

A
  1. Determine cell type (small vs non-small):
    • Small cell = rapidly dividing –> main treatment is chemotherapy
    • Non-small cell = grows slower:
      • If operable –> surgery
      • If inoperable –> radiacl radiotherapy or palliative
  2. Getfitinib or Erlotinib:
    • Use: when positive for EGF-R (epidermal growth factor receptor) mutations
    • MoA: EGF-R inhibitor
    • Epidermal growth factor receptor (EGFR) mutations are found in many cancers, particularly NSCLC – tumour tissue sample can confirm EGFR +ve or –ve for mutations
18
Q

How is a pleural effusion investigated?

A

Thoracentesis‘pleural tap’

  • Often involves ultrasound to determine degree of effussion + depth to insert needle
  • Cannula or hollow needle inserted between ribs into pleural space under local anaesthesia for diagnostic or therapeutic purposes
  • Can be used to diagnose the following:
    • Malignancy
    • Empyema
    • Pleuritic TB
    • Pleuritic lupus
    • Oesophageal rupture
    • Hemothorax
    • Chylothorax - type of pleural effusion resulting from accumulation of chyle in pleural space due to obstruction of thoracic duct (chyle = lymph formed in lacteals of the digestive system during absorption of dietary fatty acids – suspended in chylomicrons)
19
Q

Gross analysis of pleural effusion fluid can give some indication as to the diagnosis (non-definitive or highly accurate) - what do the following indicate:

  1. Bloody
  2. White (milky)
  3. Black
  4. Yellow-green
  5. Dark green
  6. Pus
A
  1. Bloody = malignancy, asbestosis, pulmonary infarction
  2. White (milky) = chylothorax, cholesterol effusion
  3. Black = aspergillus
  4. Yellow-green = rheumatoid pleurisy
  5. Dark green = bilothorax
  6. Pus = empyema
20
Q

Describe transudate vs exudate effusions

A

Transudate:

  • Caused by imbalance of hydrostatic and oncotic pressures that results in movement of fluid out of circulation and into the pleural space
    • Oncotic pressure = osmotic pressure exerted by proteins, ↑ protein = ↑ oncotic pressure e.g. albumin in blood exerts oncotic pressure that tends to pull H20 into blood vessels
  • Any movement of fluid from peritoneal or retroperitoneal spaces into pleural space = transudate

Excudate:

  • Tends to be caused by inflammation which causes:
    1. Endothelial seperation
    2. Vessel dilation
  • The above combo –> allows leakage of proteins, cholesterol and fluid into pleural space
21
Q

What criteria can be used to identify an exudate fluid?

A

Light’s Criteria

BTS reccomend that:

  • Pleural fluid protein > 30 g/L = exudate
  • Pleural fluid protein g/L = transudate
  • If protein level is between 25-35 then apply Light’s Criteria

If ANY of Light’s criteria are met then fluid is exudate:

  1. Pleural fluid protein : serum protein ratio > 0.5
  2. Pleural fluid LDH : serum LDH > 0.6
  3. Pleural fluid LDH > 2/3 the upper limit of normal serum LDH

N.B. normal serum LDH range = 100-250 U/L

22
Q

Name some causes of Transudate and Exudate effusions.

A

Transudate: - anything that ↓ blood [protein] or ↓ blood osmolality

  1. Congestive heart failure (most common)
  2. Liver Cirrhosis - causes hypoalbuminaemia
  3. Nephrotic syndrome (↑ glomerular permeability –> causes loss of protein from plasma to urine e.g. hypoalbuminaemia –> ↓ oncotic pressure –> fluid moves out of intravascular space e.g. pitting oedema, pleural effusion, ascities and periorbital oedema)

Exudate:

  1. Infection: Pneumonia (most common), TB
  2. Connective tissue disease: rheumatoid arthritis, systemic lupus erythematosus (SLE)
  3. Neoplasia: lung cancer, mesothelioma, metastases
  4. Pancreatitis
23
Q

What other features of pleural fluid (besides protein and LDH) can be analysed?

A
  • Glucose analysis:
    • Low glucose:
      • Common: pneumonia, malignant effusion
      • Rare: RA, TB
  • pH:
    • ↓ pH seen in: –> empyema, malignancy, rheumatoid pleurisy, TB pleurisy, oesophageal rupture
    • pH < 7.2 + pneumona –> chest drain
  • Amylase:
    • If pleural fluid amylase > upper limit of normal serum amylase or pleural fluid amylase : serum amylase ratio > 1.0 then;
      • Acute pancreatitis
      • Chronic pancreatic pleural effusion
  • Cytology:
    • Useful in suspected malignancy
24
Q

If a patient has an adenocarcinoma which tests positive for EGF-R mutations - does this improve or worsen their prognosis?

A

Improve

  • They can be treated with gefitinib or erlotinib –> ~ doubles survival
25
Q

What management options are there for recurrent pleural effusions?

A
  1. Recurrent aspiration
  2. Pleurodesis
  3. Indwelling pleural catheter
26
Q

What red flags are there for Lung Cancer?

A
  1. Weight loss
  2. Haemoptysis
  3. Lethargy
  4. Clubbing
  5. Dysphagia
  6. Hoarse voice
  7. Facial swelling - due to super vena caval obstruction
  8. Limb pain - hypertrophic osteoarthropathy (HPOA)
  9. Recurrent chest infections
  10. Chest pain
  11. Persistent SoB

Medicine year 3 ANNA (30 decks)

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