Lecture 26 - Malignant Lung Pathology

Question 1

What is a lung tumour?

Answer 1

tumours within the lung that possess lethal abnormal characteristic that enables them to invade and metastasize/ spread to other tissues

Question 2

What proportion of primary malignant lung tumours are carcinomas

Answer 2

more than 90%

Question 3

What are the 4 types of carcinomas

Answer 3

squamous cell carcinoma - 20-30%
small cell carcinoma - 15-205
adenocarcinoma - 30-40%
large cell undifferentiated carcinoma - 10-15%

Question 4

What are carcinoid tumours?

Answer 4

low grade malignant tumours, better survival

Question 5

What are malignant mesenchymal tumours?

Answer 5

very rare, most common type is synovial sarcoma

Question 6

What are primary lung lymphomas?

Answer 6

Rare, can be seen in HIV/AIDS patients

Question 7

What are secondary lung tumours?

Answer 7

Very common, more common than primary tumours

Usually present as multiple discrete nodules, can also be solitary

Most common are carcinomas from various sites eg. Breast, GI tract, Kidney
Sarcomas
Melanomas
Lymphomas

Question 8

Epidemiology of lung cancer

Answer 8

Most common cause of cancer death in the UK.
In the UK around 45,000 new cases are diagnosed each year and > 30,000 deaths/year

Males slightly more than females

Major public health problem

Age usually between 40-70,
rare in younger individuals

Question 9

What is a major risk factor for lung cancer

Answer 9

cigarette smoking

incidence and mortality rates have been decreasing in men since 1990’s, due to decrease smoking rates

Question 10

What is the overall prognosis for lung cancer?

Answer 10

Poor

5 year survival is between 5-10%

Question 11

What is the aetiology of lung cancer?

Answer 11

tobacco smoking
occupational/industrial hazards - asbestos, uranium, arsenic, nickel

Radiation - mines in which there is radon
-survivors of the atomic bomb in Japan after 2nd world war had a high incidence of lung cancer

Lung fibrosis - old terminology ‘scar cancers’ has been challenged
- increase risk of lung cancer in patients with pulmonary fibrosis

• Genetic mutations EGFR, KRAS, ALK etc
• usually seen lung cancers in never smokers

Question 12

What is the pathogenesis of lung cancer?

Answer 12

Not very well understood.

Mutations in key genes regulating cell profileration, DNA repair and apoptosis

Squamous carcinoma - cigarette smoking is an irritant,

(squamous metaplasia - dysplasia - carcinoma in-situ - frank squamous carcinoma)

Question 13

what is the effect of cigarette/tobacco smoking on lung cancer

Answer 13

it is a major risk factor
tobacco smoke is a carcinogen
almost linear relationship between no. of cigarettes smoked daily and risk of developing lung cancer

Question 14

What is a ‘pack year’?

Answer 14

1 pack year - 20 cigarettes per day for 1 year

-40 cigarettes per day for 6 months

Question 15

Does passive smoking increase risk for lung cancer

Answer 15

Yes

Question 16

Where do 2/3rd of world smokers reside?

Answer 16

china

lung cancer death in china is expected to run into millions by mid-21st century

Question 17

What is the latent period between asbestos exposure and development of carcinoma

Answer 17

about 20 years

Question 18

How much is risk of lung cancer increased of asbestos in combination with cigarette smoking

Answer 18

20-100 fold

Question 19

What other respiratory illnesses is asbestos exposure associated with?

Answer 19

lung fibrosis and mesothelioma (malignant tumour of the pleura)

Question 20

what are the clinical features of lung cancer?

Answer 20

local effects of tumour
distant metastases
non-specific features
asymptomatic, discovered incidentally

Question 21

What are local effects of lung cancer?

Answer 21

Central tumours arising in proximal airways can ulcerate and bleed - haemoptysis

Tumour obstructing airways with distal collapse or consolidation - breathlessness or features of pneumonia

tumour infiltrating into adjacent structures eg.

pleura - pleura effusion presenting as breathlessness

Question 22

Tumour infiltrating into pleura

Answer 22

pleural effusion presenting as breathlessness

Question 23

Tumour infiltrating into chest wall/ribs

Answer 23

pain

Question 24

Tumour infiltrating into recurrent laryngeal nerve

Answer 24

hoarseness

Question 25

Tumour infiltrating into oesophagus

Answer 25

dysphagia

Question 26

Tumour infiltrating into sympathetic trunk

Answer 26

horner’s syndrome -sympathetic chain - combination of symptoms

Question 27

How can distant metastases present?

Answer 27

with disseminated disease

common sites - lymph nodes, pleura, liver, bone, adrenal, brain

Depending on the site can present with pathological fractures, seizures, lumps in neck etc.

Question 28

What are the non-specific features of lung cancer?

Answer 28

• Usually metabolic effects
• Weight loss, lethargy
• Electolytic disturbances, eg small cell carcinoma - hyponatraemia, hypokalaemia, hypercalcaemia in SCC
• Finger clubbing

Question 29

What is lymphangitis carcinomatosa?

Answer 29

Lymphatics within the lung are diffusely involved by tumour

Question 30

What is the management of lung cancer?

Answer 30

a small % of patients diagnosed with early stage (limited to lung or extension into local nodes), are offered surgery or radical radiotherapy

Majority present with advanced disease - until recently options were limited to chemotherapy or palliative radiotherapy

Question 31

Recent advances in treatment of lung cancer with advanced disease

Answer 31

• Target/tailored therapy
• based on tumour genomics eg. EGFR mutations, ALK re-arrangements
• Immune checkpoint inhibitors eg. PD- L1