Pathology of Lung Cancer

Question 1

What are risk factors for lung cancer?

Answer 1

Cigarette smoking
Environmental tobacco exposure
Radon gas exposure
Asbestos exposure

Question 2

What % of smokers get lung cancer?

Answer 2

10%

Question 3

What are the two main patterns of carcinogenesis in the lung?

Answer 3

In lung periphery, bronchoalveolar epithelial stem cells transform = adenocarcinoma

In central lung airways - bronchial epithelial stem cells transform = squamous cell carcinoma (most strongly associated with smoking)

Question 4

What is the carcinoma sequence of an adenocarcinoma?

Answer 4

Atypical adenomatous hyperplasia –> adenocarcinoma in situ –> invasive adenocarcinoma

Question 5

What are key driver mutations in adenocarcinomas?

Answer 5

KRAS (smoking induced) 
EGFR
BRAF
HER2
ALK rearrangements

Question 6

What are tumours of the lung?

Answer 6

Benign causes of mass lesion 
Carcinoid tumours
Lung neoplasms
Low grade malignancies of bronchial glands
Adenoid cystic carcinoma
Lymphoma
Lung mets (common)

Question 7

What are the four main types of lung cancer?

Answer 7

Squamous cell (40%)
Adenocarcinoma (41%)
Small cell carcinoma (15%)
Large cell carcinoma (4%)

largely split into small cell lung cancer and non-small cell lung cancer

Question 8

How late/early does lung cancer tend to present?

Answer 8

Tends to present late

Question 9

What are the local effects of lung cancer?

Answer 9

Bronchial obstruction –> collapse, endogenous lipoid pneumonia, infection, abscess, bronchiectasis

Question 10

What is an endogenous lipoid pneumonia?

Answer 10

Obstructed airway –> accumulation of cellular breakdown debris, incl cholesterol from destroyed alveolar walls

(these lipids are difficult to digest and the macrophages which attempt to phagocytose them accumulate within alveolar spaces)

Pleural effects - infalmmatory/malignant

Direct invasion of chest wall/nerves/mediastinum (–> SVCO, pericardial problems)

LN mets - mass effect, lymphangitis carcinomatosa

Question 11

What nerves can be damage in a lung cancer?

Answer 11

Phrenic –> diaphragmatic paralysis

L recurrent laryngeal –> hoarse voice, cough

Brachial plexus (pancoast tumour –> T1 damage)

Cervical sympathetic –> Horner’s syndrome

Question 12

What are common places for lung mets?

Answer 12

Liver
Adrenals
Bone
Brain 
Skin

Question 13

What are paraneoplastic effects of small cell lung cancer?

Answer 13

SIADH
ACTH - not typical, HTN, hyperglycaemia, hypokalaemia, alkalosis and muscle weakness more common than buffalo hump etc.
Lambert-Eaton syndrome

Question 14

What are the paraneoplastic features of squamous cell lung cancer?

Answer 14

PTHrP secretion –> hypercalcaemia
Clubbing
Hypertrophic pulmonary osteoarthropathy
Hyperthyroidism due to ectopic TSH

Question 15

What are the paraneoplastic features of adenocarcinoma?

Answer 15

Gynaecomastia

Hypertrophic pulmonary osteoarthropathy

Question 16

What is often the first investigation done in patients with suspected lung cancer?

Answer 16

CXR

Question 17

What is the investigation of choice to investigate suspected lung cancer?

Answer 17

CT

Question 18

What investigation is done to reach a histological diagnosis in lung cancer?

Answer 18

Bronchoscopy + biopsy (sometimes aided by endobronchial USS)

Question 19

When is PET scanning done in lung cancer?

Answer 19

In NSC lung cancer to establish eligibility for curative treatment

Question 20

How does PET scanning work?

Answer 20

Uses 18-fluorodeoxygenase which is preferentially taken up by neoplastic tissue

Question 21

What FBC abnormality may you see in lung cancer?

Answer 21

Raised platelets