Lung Neoplasms

Question 1

Types of lung cancers.

Answer 1

1. Carcinomas (90-95%) - malignant tumours of epithelial origin.
2. bronchial carcinoids (5%)
3. Mesenchymal or other (2.5-5%)

Question 2

Risk factors for developing lung cancer

Answer 2

Smoking is the biggest risk factor (90% of cancers attributed to tobacco smoking).

Other risk factors include:

• ionising radiation
• asbestos exposure (5x, add smoking 50-90x risk - 10-30 year latent period)
• atmospheric pollution (esp. radon gas).
• Fx lung cancer

Question 3

Main classification system of carcinomas

Answer 3

1. Small cell lung cancer (SCLC) (13%)
2. Non-small cell lung cancer (NSCLC)
   - SCC (20%)
   - Adenocarcinoma (40%)
   - Large cell carcinoma (5%)

Question 4

Adenocarcinoma

Answer 4

Including bronchoalvolar carinoma.

Most common type of cancer to occur in non-smokers, OCCURS PERIPHERALLY. Incidence is rising.

Question 5

Squamous cell carcinoma

Answer 5

Occurs commonly in proximal bronchi.

Question 6

Small cell carcinoma.

Answer 6

Usually an inoperable proximal bronchial mass, strong relationship to msoking, commonly associated with paraneoplastic syndromes.

Question 7

Macroscopic features of lung cancers

Answer 7

In general, most lung cancers arise from the bronchial epithelium (giving the generic term ‘bronchiogenic carcinoma’) and are most commonly found around the hilium of the lung (ex. adenocarcinoma).

Regardless of subtype, all lung cancers tend to appear macroscopically as irregular, heterogeneous tumours that are grey, yellow or brown in appearance. Mucin may be seen and haemorrhage and necrosis is common. Infiltration of surrounding tissue is often seen macroscopically and there may be downstream consolidation and pneumonia secondary to bronchial obstruction.

Question 8

Precursor lesions

Answer 8

1. Squamous dysplasia and carcinoma in situ
2. Atypical adenomatous hyperplasia
3. Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia

Question 9

Clinical presentation of lung cancer

Answer 9

40-60 years of age. Major presenting complaints:

• cough (75%)
• weight loss (40%)
• chest pain (20%)
• dyspnoea (20%)
• haemoptysis (25-50%)
• hoarseness

Lung tumours frequently present at an advanced stage, as symptoms of pain, weight loss and dyspnoea do not occur until later.

Frequently there may be pneumonia, pleural effusiona nd pain secondayr to chest wall invasion.

Question 10

Why does hoarseness and change of voice occur?

Answer 10

Involvement of recurrent laryngeal nerve.

Question 11

Superior vena cava syndrome

Answer 11

Obstruction of the SVC is more commonly seen in SCLC than NSCLC. This can lead to a sensation of fullness in the head, dilated neck veins, a plethoric appearance and facial oedema.

Question 12

Pancoast’s syndrome

Answer 12

usually NSCLC arising in the superior sulcus.
Manifested by pain (usually in the shoulder, and less commonly in the forearm, scapula and fingers) + Horner’s syndrome + bony destruction (first and second ribs, vertebrae) and atrophy of hand muscles.

Question 13

Horner’s Syndrome

Answer 13

Indicates a lesion in the sympathetic pathway that results in ptosis, miosis and anhidrosis. In lung cancer this is because of the path over the apex of the lung

Question 14

Paraneoplastic syndromes

Answer 14

May also occur where tumours, especially small cell and neuroendocrine tumours, secrete hormones (including SIADH (hyponatremia), ACTH, serotonin (Cushing’s syndrome), PTHrP (hypcercalcaemia - more common in SCC). Neurological abnormalities can also occur.

Classical signs may include hypertrophic pulmonary osteoarthropathy (clubbing, periosteal proliferation of the tubular bones) (especially with adenocarcinoma). May be associated with other lung disease.

Question 15

Lung cancer spread

Answer 15

Local extension (to the pleural surface)
Lymphatic spread (to nodes and beyond)
Through the blood

With the exception of SCC, lung cancers spread early and aggressively, with the adrenals (50%), liver (30-50%), brain (20%) and bone (20%) being common sites for distant metastasis.

Question 16

Difference between treatment in NSCLC and SCLC

Answer 16

Small cell cancers are highly chemosensitive and tend to metastasis early.
NSCLC are more responsive to radiotherapy.

Question 17

Staging for NSCLC

Answer 17

Staging determines the appropriate treatment for a patient with resectable disease and avoiding unneccesary surgery in advanced disease.

Chemoradiotherapy is used for more extensive disease.

Staging utilises the tumour, node, metastasis (TNM) system which can then be assigned a stage from I-IV.

Question 18

Staging of SCLC

Answer 18

At the time of presentation, almost all have disseminated disease and surgery is not an option. These patients receive chemotherapy.

Staging uses the TNM (esp. potentially resectable tumours) or Veterans Administration Lung STudy Group designations of limited (confined to one hemithorax) or extensive (beyond one hemithorax) disease.

This distinction is important since patients with limited disease may benefit from thoracic radiotherapy in addition to systemic chemotherapy.

Question 19

Carcinoid tumours

Answer 19

These can occur in the lung (1-5% of all lung tumours). Neuroendocrine neoplasm of low malignant potential - most bronchial carcinoids do not metastasise. Classified into typical and atypical. Most are confined to the main stem bronchi and rarely exceed 3-4cm in diameter. These tumours are not related to smoking. Most patients are less than 40 (M:F 1:1).

Clinically they present with symptoms secondary to the intraluminal growth (ie cough). However, occasionally carcinoids produce vasoactive substances that lead to the carcinoid syndrome - intermittent attacks of diarrhoea, flushing and cyanosis.

Question 20

Metastatic tumours

Answer 20

The lung is the most common site for metastasis for most carcinomas and sarcomas. Generally metastatic tumours are multifocal, with discrete nodules of varying sizes spread throughout both lungs (primary tumours are rarely multifocal). They tend to be perbronchial (where the vessels and lymphatics are) and occasionally tumour embolisation can occur, giving symptoms of PE.

Question 21

Mesothelioma aetiology

Answer 21

Arise from mesothelial surface of the pleura. Increased incidence among people with heavy metal exposure to asbestos.

Long latency period of 25-45 years for the development of asbestos related mesothelioma. Estimated 7-10% lifetime risk for people with heavy metal exposure of asbestos.

Evidence of exposure includes asbestos bodies and asbestos plaques.

Question 22

Macroscopic appearance of mesothelioma

Answer 22

Diffuse lesion that spreads in the pleural space ensheathing and invading local tissue that is usually associated with a pleural effusion.

Question 23

Microscopic appearance of mesothelioma

Answer 23

Mixture of two cell types, one of which may predominate. EM.

Mesothelial cells can differentiate into either epitheloid cuboidal, columnar or flattened cells forming tubular or papillary structures resembling adenocarcinoma (epitheloid type). Particular immunohistochemistry staining needed to differentiate from metastatic tumours.

The mesenchymal type of mesothelioma appears like a spindle cell sarcoma (sarcomatoid type). The mixed type of mesothelioma contains both epitheloid and sarcomatoid patterns.

Question 24

EM appearance of mesothelioma

Answer 24

Presence of long tonofilaments but absent micro villous rootlets and lamellar bodies.

Question 25

Clinical symptoms of mesothelioma

Answer 25

Chest pain, dyspnoea and recurrent pleural effusions.

Lung is invaded directly and there is often metastatic spread to the hilar lymph nodes and liver.

Question 26

Prognosis of mesothelioma

Answer 26

50% die within 12 months of diagnosis, few survive beyond 2 years. Aggressive surgical, chemo- and radiotherapy may improve the poor prognosis.