Lung Cancer

Question 1

How common is Lung cancer in the UK?

Answer 1

It is the 3rd most common cancer in the UK behind breast and prostate.

Question 2

What is the main cause of lung cancer?

Answer 2

Cigarette smoking - 80% of cancers preventable.

Question 3

What is the histology of lung cancer?

Answer 3

Non-small cell lung cancer:

• squamous cell carcinoma (35%)
• Adenocarcinoma (25%)

Small cell lung cancer (20%)

Question 4

How are small cell cancers responsible for paraneoplastic syndromes?

Answer 4

Small cell lung cancers contain neurosecretory granules that can release neuroendocrine hormones.

Question 5

What is a paraneoplastic syndrome?

Answer 5

A syndrome that is the consequence of cancer in the body specifically due to the production of chemical signalling molecules (such as hormones or cytokines) by the tumour cells or by an immune response against the tumour.

Question 6

What are the signs and symptoms of lung cancer?

Answer 6

• SOB
• Cough
• Haemoptysis
• Finger clubbing
• Recurrent pneumonia
• Weight loss
• Lymphadenopathy - often supraclavicular nodes are the first to be found on examination.

Question 7

What investigations should be carried out to investigate lung cancer?

Answer 7

1. CXR - 1st line.
2. Staging CT scan - contrast enhanced
3. PET-CT
4. Bronchoscopy with endobronchial ultrasound (EBUS)
5. Histological diagnosis

Question 8

What findings on a CXR are suggestive of lung cancer?

Answer 8

1. Hilar enlargement
2. Peripheral opacity - a visible lesion in the lung field
3. Pleural effusion - usually unilateral in cancer
4. Collapse

Question 9

Why is a staging CT scan useful in lung cancer?

Answer 9

• Helps to establish the stage and check for lymph node involvement and metastasis.

Question 10

What is the benefit of using contrast enhanced staging CT scan in lung cancer?

Answer 10

This gives more detailed information about different tissues.

Question 11

What is the rationale for using a PET-CT in lung cancer?

Answer 11

PET-CT injects a radioactive tracer - normally attached to glucose molecules. Therefore taking images using a combination of a CT scanner and a gamma ray detector help to visualise how metabolically active various tissues are. Therefore this is useful in identifying areas that the cancer has spread to by showing areas of increased metabolic activity suggestive of cancer.

Question 12

What is the benefit of using EBUS with lung cancer?

Answer 12

Bronchoscopy with endobroncial ultrasound is endoscopy of the airways with ultrasound on the end of the scope. This allows for detailed assessment of the tumour and ultrasound guided biopsy.

Question 13

What are the 2 methods for obtaining a histological sample of lung cancer?

Answer 13

1. Bronchoscopy

2. Percutaneously

Question 14

What is the treatment in non-small cell lung cancer?

Answer 14

1. Surgery - in patients that have disease isolated to a single area with intention to cure the cancer.
   - Lobectomy = first line.
   - Segmentectomy or wedge resection is also an option.
2. Radiotherapy if early can be curative
3. Chemotherapy in addition to surgery or radiotherapy to improve outcomes (adjuvant chemotherapy) or as palliative

Question 15

What is the first line treatment for non-small cell cancer?

Answer 15

Surgery - Lobectomy/segmentectomy.

Question 16

What is the treatment for small cell cancer?

Answer 16

• usually chemotherapy and radiotherapy. Prognosis is worse for small cell lung cancer than non-small cell cancer.

Endobrachial treatment with stents or debulking can be used as part of palliative treatment to relieve bronchial obstruction caused by lung cancer.

Question 17

How is recurrent laryngeal nerve palsy related to lung cancer?

Answer 17

recurrent laryngeal nerve palsy presents with hoarse voice. It is cause by the cancer pressing on or affecting the recurrent laryngeal nerve as it passes through the mediastinum.

Question 18

How is phrenic nerve palsy related to lung cancer?

Answer 18

Due to nerve compression causing the diaphragm to weaken and presents as shortness of breath.

Question 19

How does superior vena cava obstruction result as a complication of lung cancer?

Answer 19

It is caused by direct compression of the tumour on the superior vena cava.

Question 20

How does superior vena cava obstruction present?

Answer 20

Facial swelling
Difficulty breathing
Distended veins in the neck and upper chest

Pemberton’s sign - when raising the hands over the head causes facial congestion and cyanosis - Medical emergency

Question 21

What is Horner’s syndrome?

Answer 21

Triad of - partial ptosis, miosis and anhidrosis.

Caused by Pancoast’s tumour - tumour in the pulmonary apex, pressing on the sympathetic ganglion

Question 22

How is SIADH caused by small cell lung cancer?

Answer 22

SIADH is caused by ectopic ADH secretion by a small cell lung cancer and presents with hyponatraemia.

Question 23

How can Cushing’s syndrome be caused by small cell lung cancer?

Answer 23

ectopic ACTH secretion by a small cell lung cancer.

Question 24

How can hypercalcaemia be caused by a squamous cell carcinoma?

Answer 24

ectopic parathyroid hormone from a squamous cell carcinoma.

Question 25

What is limbic encephalitis and how is it related to lung cancer?

Answer 25

This is a paraneoplastic syndrome where the small cell lung cancer causes the immune system to make antibodies to tissues in the brain, specifically the limbic system, causing inflammation in these areas. This causes symptoms such as short term memory impairment, hallucinations, confusion and seizures. It is associated with anti-Hu antibodies.

Question 26

What is Lambert-Eaton myasthenic syndrome?

Answer 26

Lambert-Eaton myasthenic syndrome is a result of 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. This leads to 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.

Question 27

What is the main DDx for Lambert-Eaton myasthenic syndrome?

Answer 27

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 28

What is mesothelioma?

Answer 28

Mesothelioma is a 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.