Lung Cancer

Question 1

histology of lung cancer

Answer 1

1. small cell lung cancer
   - neuro secretory granules which release neuroendocrine hormones
2. non small cell lung cancer
   - squamous cell carcinoma
   - adenocarcinoma

Question 2

lung cancer signs and symptoms

Answer 2

Shortness of breath
Cough
Haemoptysis (coughing up blood)
Finger clubbing
Recurrent pneumonia
Weight loss
Lymphadenopathy – often supraclavicular nodes are the first to be found on examination

Question 3

lung cancer investigations

Answer 3

Chest xray is the first line investigation in suspected lung cancer. Findings suggesting cancer include:

Hilar enlargement
“Peripheral opacity” – a visible lesion in the lung field
Pleural effusion – usually unilateral in cancer
Collapse
Staging CT scan of chest, abdomen and pelvis to establish the stage and check for lymph node involvement and metastasis. This should be contrast enhanced using an injected contrast to give more detailed information about different tissues.

PET-CT (positron emission tomography) scans involve injecting a radioactive tracer (usually attached to glucose molecules) and taking images using a combination of a CT scanner and a gamma ray detector to visualise how metabolically active various tissues are. They are useful in identifying areas that the cancer has spread to by showing areas of increased metabolic activity suggestive of cancer.

Bronchoscopy with endobronchial ultrasound (EBUS) involves endoscopy of the airways (bronchi) with ultrasound on the end of the scope. This allows for detailed assessment of the tumour and ultrasound guided biopsy.

Histological diagnosis to check the type of cells in the cancer requires a biopsy. This can be either by bronchoscopy or percutaneously (through the skin).

Question 4

lung cancer treatment

Answer 4

non small cell lung cancer:
- surgical: where disease isolated to a single area: surgery. *segmentectomy / wedge resection is taking a segment or wedge of the lung

• radiotherapy: if early enough
• chemotherapy: adjuvant

small cell lung cancer:
chemotherapy and radiotherapy
prognosis is worse
endobronchial treatment with stents/ debulking for palliative.

Question 5

extrapulmonary manifistations of lung cancer

‘paraneoplastic syndromes’

Answer 5

recurrent laryngeal nerve palsy: hoarse voice (cancer pressing on the recurrent laryngeal nerve)

phrenic nerve palsy (compression) diaphragm weakness, SOB

SVC syndrome: direct compression of the tumour on the SVC. facial swelling, difficulty breathing, Pemberton sign

Horner’s syndrome. ptosis, anhidrosis, miosis. Pancoasts tumour in the pulmonary apex pressing on the sympathetic ganglion

SIADH (ectopic ADH) by small cell lung cancer (hyponatraemia)

Cushing’s (ectopic ACTH by SCC)

Hypercalcaaemia (ectopic PTH from SCC)

limbic encephalitis (SCC causes immue ssytem to make antbiodies to tissue in the brain especially limbic system- short term memory impairment, hallucination, confusion, sezirues) *anti Hu antibodies

Question 6

Lambert-Eaton myasthenic syndrome

Answer 6

antibodies produced by the immune system against small cell lung cancer cells.

These antibodies also target and damage voltage-gated calcium channels sited on the presynaptic terminals in motor neurones.

symptoms: weakness, particularly in the proximal muscles but can also affect intraocular muscles causing diplopia (double vision), levator muscles in the eyelid causing ptosis and pharyngeal muscles causing slurred speech and dysphagia (difficulty swallowing). This weakness gets worse with prolonged used of the muscles.

This syndrome has similar symptoms to myasthenia gravis although the symptoms tend to be more insidious and less pronounced in Lambert-Eaton syndrome. In older smokers with symptoms of Lambert-Eaton syndrome consider small cell lung cancer.

Question 7

Mesothelioma

Answer 7

lung malignancy affecting the mesothelial cells of the pleura. It is strongly linked to asbestos inhalation. There is a huge latent period between exposure to asbestos and the development of mesothelioma of up to 45 years. The prognosis is very poor. Chemotherapy can improve survival but it is essentially palliative.