Respiratory pathology - Lung cancer Flashcards
Describe the epidemiology of lung cancer?
- Third most common cause of death in UK
- 1/4 of cancer deaths
- 5 year survival is 5.5%
What are some causes of lung cancer?
- tobacco
- asbestos
- radon
What is the trend in smoking and how is it associated with mortality from lung cancer?
- Steady decline in smoking prevalence among men over the years
- The peak prevalence for women was about 15 years later
- Mirrors the mortality of lung cancer
- Mortality in men is declining over time
What are some clinical features of lung cancer?
MANY HAVE NO SYMPTOMS
unexplained/persistant for over 3 weeks:
- cough
- shoulder/chest pain
- dyspnoea
- hoarseness
- finger clubbing - greater than 180 degrees
HAEMOPTYSIS - coughing blood
What is done it if a patients presents with symptoms which could be due to lung cancer?
- X ray referral - URGENT
- If it shows a mass then a biopsy is taken
How are tumours typed and staged?
- Small cell or non small cell?
- Tumour, nodes and metasteses (e.g. T1a - letters for each of 3 parts)
What factors are considered in order to stage a tumour?
- Location of tumour indicated
- If closer to mediastinum/ chest wall/ spreads to lymph nodes in neck, has higher T staging
- Surgery impractical if spreads to lymph nodes
- Location, size and proximity to other organs
- Has it spread to other places
How are PET scans done?
- Patients have to fast for 4 hours
- Given radioactive glucose
- Tumour much more metabolically active
How is metastasis identified?
- Looking at scans, MRI, CT
What are the stages involved in lung cancer diagnosis?
- Scan
- Biopsy
- Benign/Malignant
- Type?
- Staging
- Functional capacity of person
- Prognosis
What is a trans-thoracic CT biopsy, advantages/disadvantages?
- Using CT guidance through thorax
- real time, sensitive
- risk of pneumothorax, small sample size, in case of bleeding no immediate therapy possible
Why must the patients physical condition be assessed before considering a treatment plan?
- They may have other health conditions which affect treatment
- Are they fit to undergo treatment?
What does prognosis of lung cancer depend on?
- Prognosis depends on the cell type and the extent of the spread
How can cytology be done - where and how are specimens obtained?
Cytology:
- Sputum
- Bronchial washings and brushings
- Pleural fluid
- Endoscopic fine needle biopsy of tumour/lymph nodes
How are biopsies obtained for histology (looking at tissues)?
Histology:
- Biopsy at bronchoscopy - central tumours
- Percutaneous CT guided biopsy - peripheral tumours
- Mediastinoscopy and lymph node biopsy - for staging
- Open biopsy at time of surgery
Types of non-small cells carcinomas
- squamous cell carcinoma
- adenocarcinoma (glands)
- large cell carcinoma
What is small cell carcinoma?
- They grow rapidly and metastasise early so it is unusual to find an early stage small cell carcinoma
- Worse than non-small cell
What is squamous cell carcinoma and its features?
- develops by multi-step pathway
- changes from normal to squamous epithelium (found in skin)
- reversible at the start
- local spread, late metastasis
- arise centrally
- associated with smoking
Adenocarcinoma
- common in non-smokers too
- atypical adenomatous hyperplasia - atypical cell proliferation lining alveolar walls
- different pathways in smokers and non-smokers
- metastise common and early
What is large cell carcinoma and its features?
- anything doesn’t fit as adenocarcinoma or sqaumous
- poorly differentiated
- show some evidence of glandular, squamous or neuroendocrine differentiation on EM
- probably poorly differentiated adeno/squamous cell carcinomas
- poorer prognosis
What is small cell carcinoma and its features?
- small cells
- not differentiated
- keep proliferating
- outgrow blood supply so become necrotic
- often near central bronchi
- smoking association
- most present with advanced diseasee
- bad prognosis
- paraneoplastic syndrome association
What is the difference between small cell and non small cell carcinoma in terms of survival rate and treatment?
small cell - low survival rate, chemo-radiotherapy
non small cell - early stage has higher survival rate (60%). Some suitable for surgery. Less chemosensitive
Why is it important to sub type non small cell carcinomas?
- Treatment depends on type
- Chemo better for adenocarcinoma
Targetted therapy
- Looking at mutation type to target therapy
What is a EGFR mutation?
common
- membrane receptor tyrosine kinase
- regulates apoptosis, proliferation, migration, angiogenesis and migration
- mutated in lung cancer so always on
- more common in non-smokers, females, asian.
- Common in adenocarcinoma
- target of TKI
What is ALK mutation?
not common
- mutations on downstream effects including tumour growth
- non smokers may have it
- Can use FISH
What is immunemodulatory therapy?
- Tumours evade immune system
- PDL-1 made by tumours to inhibit cytotoxic T cells (drug target developed)
What are the symptoms that may occur due to tumour invasion in other tissues
- bronchial obstruction = collapse of lung can cause shortness of breath, impaired bronchial drainage can cause chest infections
- invasion of airway and vessels = cough, haemoptysis
- oesophagus invasion = dysphagia (hard to swallow)
- nerves = Horners syndrome
- chest wall = pain
- large vessel invasion = SVC congestion of head and arm, headache
- invasion of pleura/pericardium = breathlessness, cardiac compromise
What are the physical signs of distant spread of bronchogenic carcinoma?
- brain fits
- skin lumps
- liver pain
- bones pain/fractures
What is a paraneoplastic syndrome?
systemtic effect of tumour due to abnormal expression by tumour cells of factors like hormones not normally expressed. E.g. endrocine can cause syndrome of inappropriate ADH causing hyponatremia (low sodium)
What are the different parts of TNM staging and give some examples
Primary tumour (T):
TX can’t be assessed
T0 no evidence
T1 <3 cm + surrounded by lung or pleura + no bronchoscopic evidence of invasion into a main bronchus
T2 >3 cm or involves main bronchus >2 cm from carina or invades visceral pleura
T3 invades chest wall or diaphragm or mediastinal pleura or parietal pericardium or main bronchus <2 cm from carina
T4 malignant pleural effusion or invades mediastinum or heart or great vessels or trachea or oesophagus or carina or vertebral body
Lymph node (N)
NX can’t be assessed
N0 no regional lymph node metastasis
N1 metastasis in ipsilateral peribronchial / hilar node
N2 metastasis in ipsilateral mediastinal / subcarinal node
N3 metastasis in contralateral mediastinal / hilar, ipsilateral / contralateral scalene, or supraclavicular node
Distant metastasis (M) MX can’t be assessed M0 no distant metastasis M1a metastasis within lung M1b metastasis outside lung
