Lung Cancer Flashcards
What does survival depend on?
- How big the tumour is
- What it has invaded locally
- Distant spread to other nodes and tissues
What system is used to stage lung cancer?
TNM system
Survival rate of stage 1 lung cancer?
More than 55% will survive their cancer for 5 years or more after diagnosis
Survival rate of stage 2 lung cancer?
Around 35% will survive their cancer for 5 years or more after
What % of lung cancers are operable?
Unfortunately, only a small percentage of patients with lung cancer are operable by the time they are diagnosed.
This is approximately 20%.
Why does lung cancer have such a poor prognosis?
Presents late
What is the respiratory epithelium?
A type of ciliated columnar epithelium
What can happy if the bronchial epithelium are irritated e.g. cigarette smoke?
To adapt, they change into a stronger epithelium e.g. squamous –> this is called squamous metaplasia
What is squamous metaplasia?
Squamous metaplasia is a benign non-cancerous change (metaplasia) of surfacing lining cells (epithelium) to a squamous morphology.
If the irritation of the respiratory epithelium continues, what can occur?
- Damage to genetic materials within cells (body can deal with this via apoptosis or immune surveillence)
- Sometimes a neoplastic cell will develop (can avoid body checks)
- This can independently proliferate –> dysplasia
- N.B. still above basement membrane
- This can independently proliferate –> dysplasia
If the dysplasia of respiratory epithelium continues, what can occur?
- Part/whole of epithelium can be replaced by neoplastic cells
- Part: low grade dysplasia
- Whole: high grade dysplasia or carcinoma in situ
What is ‘intraeptihelial neoplasia’?
Neoplastic cells on the epithelium but still above basement membrane
When can intraepithelial neoplasia become invasive?
When they develop the ability to invade through the basement membrane
What are the 2 main types of lung cancers?
- Non-small cell lung cancer (NSCLC): 80-85% of lung cancers
- Small cell lung cancer (SCLC) - 10-15% of lung cancers
N.B. mixed types are not unlikely
What are the 3 main types of NSCLC?
- Adenocarcinoma
- Squamous cell carcinoma
- Large cell carcinoma
Where do adenocarcinomas start?
Start in the cells that would normally secrete substances such as mucus (glandular)
Who do adenocarcinomas typically occur in?
- This type of lung cancer occurs mainly in current or former smokers, but it is also the most common type of lung cancer seen in non-smokers
- More common in women than in men
- More likely to occur in younger people than other types of lung cancer.
Where do squamous cell carcinomas start?
In squamous cells, which are flat cells that line the inside of the airways in the lungs.
Is SCLC or NSCLC more aggressive?
SCLC - This type of lung cancer tends to grow and spread faster than NSCLC
Clinical Case 1:
- Man in 60s
- Cough, haemoptysis, weight loss, increasing shortness of breath
- Smoker 20 a day for 45 years
- Ventolin (salbutamol) –> evidence of COPD
- Otherwise fit and well
Examinations:
- Clubbed, no lymphadenopathy (enlarged lymph nodes)
- Respiratory:
- Dull to percussion on left
- Decreased air entry left base
Investigations:
- Bloods - normal
- CXR - pleural effusion
- Bronchoscopy - tumour left main bronchus
- CT - tumour and mediastinal lymphadenopathy
- Biopsy result - NSCLC
Treatment?
- Pleural fluid drainage and pleurodesis
- Palliative care (tumour not treatable)
(look at year 1 lung cancer cases)
Clincal Case 2:
- 80 year old man
- Weight loss, R chest/shoulder pain, back pain
- Heaky smoker
- COPD
Examination:
- Dehydrated
- Fullness between ribs R upper chest
- No neurology R arm
- Respiratory:
- Decreased air entry R apex
- Dull R apex
- Liver large and knobbly
Investigations:
- Bloods - calcium 3.5 (raised)
- CXR
- CT
- Bronchoscopy normal
- CT guided biopsy - SCLC
Treatment and progress?
- IV fluids and pamidronate
- Palliative radiotherapy to chest wall
- Pain control (not curative)
What can presentation of lung cancer be linked to?
- Effects of primary tumour
- Effects of metastatic deposits
- Systemic effects
How can:
- Cough
- Haemoptysis
- Shortness of breath
- Chest pain
be caused by primary tumour?
- Cough: e.g. tumour irritating airways triggering cough reflex
- Haemoptysis: if invasive tumour damages vessels it can lead to coughing up blood
- Shortness of breath: e.g. tumour blocks a proximal airway, tumour causes distal infection
- Chest pain: tumour grows into parietal pleura/chest wall
How can
- Shortness of breath
- Lumps
- Neurological signs
- SVCO
be caused by metastatic deposits?
- Shortness of breath: tumour in pleural cavity/ies causes an effusion which restricts lung expansion
- Lumps: e.g. in nodes, skin, bones - may also cause bone pain)
- Neurological signs: e.g. destruction or squashing of brain tissue by brain deposits
- SVCO (Superior Vena Cava Obstruction)
What can cause these systemic effects of lung cancer:
- Weight loss
- Hypercalcaemia
- Paraneoplasic syndromes
- Weight loss: loss of appetite, changes in metabolism, etc due to circulating tumour products like cytokines
- Hypercalcaemia: eg from osteolytic metastases, and/ or parathyroid hormone related protein secretion by the tumour cells
- Paraneoplasic syndromes: other circulating tumour products
Hypercalcaemia is present in an estimated 10-20 per cent of all patients with cancer. What causes this?
- Increased osteoclastic activity induced bone resorption
- Decreased renal excretion of calcium
- Increased gut absorption of calcium
Typical symptoms of lung cancer?
- Unexplained cough for at least 3 weeks (with or without haemoptysis)
- Unintended weight loss (>5% in 6 months)
- New-onset dyspnoea
- Pleuritic chest pain (due to the tumour invading the pleura or the chest wall)
- Bone pain (due to metastases – commonly the spine, pelvis and long bones)
- Fatigue (due to anaemia of chronic disease)
Note that up to 20% of patients present with non-respiratory symptoms (such as fatigue).
How can cancer cause anaemia?
- Cancers cause inflammation that decrease red blood cell production
- Many chemotherapies are myelosuppressive, meaning they slow down the production of new blood cells by the bone marrow.
Other important areas to cover in the history of lung cancer?
- Family history
- Smoking history
- Occupation
A full respiratory examination should be performed in suspected cases of lung cancer. What are typical clinical findings?
- Cachexia
- Cancer can cause increased resting energy expenditure and lipolysis
- Finger clubbing
- Dullness to percussion
- Due to tumour (solids are less resonant than gases)
- Lymphadenopathy
- Due to metastasis to the lymphatic system
- Wheeze on auscultation
- Due to the tumour obstructing an airway
In laboratory investigations of lung cancer, what may be shown in:
- FBCs
- LFTs
- U&Es
- Serum calcium
- FBCs: anaemia
- LFTs:
- raised ALP and GGT may indicate hepatic metastases
- raised ALP may indicate bone metastases
- U&Es: Hyponatraemia may be due to syndrome of inappropriate antidiuretic hormone secretion (SIADH), which is more common in small cell carcinoma
- Serum calcium: elevated with the secretion of PTH-related protein (PTHrP)
What is first line investigation in lung cancer?
Chest x-ray
What investigation is then used to confirm chest x-ray findings?
CT
What is a bronchoscopy?
Bronchoscopy involves the insertion of a small camera into the airways to directly visualise the tumour. A biopsy of the tumour is taken.
What is essential for making the diagnosis of lung cancer?
A biopsy
From a cellular point of view, what may cause a late presentation of lung cancer?
- The process of gaining malignant genetic mutations is a stepwise process that takes years
- There are a large number of pneumocytes that have to be invaded before the lung function is significantly hampered
- Intraepithelial changes will almost always be asymptomatic
- Early invasive phases will almost always be asymptomatic
From an anatomical view point, what may cause a late presentation of lung cancer?
- Lack of pain fibres within the lung parenchyma means that a lung tumour within the centre of the lung may be asymptomatic
- Symptoms can be vague and non-specific
- There is reserve capacity in the lungs so loss of function of one small area does not necessarily cause symptoms
