Resp 7 - Lung cancer pathology Flashcards
What are common symptoms of lung cancer?
Haemoptysis
Cough (>3 weeks)
Chest/Shoulder Pain
How can samples be acquired for cytological analysis?
- Bronchoscopy & Endobronchial Ultrasounds (EBU)
- Trans-thoracic CT scan
What are the 2 major types of lung cancers?
- Non small cell cancer
- Small cell cancer
–> first step on diagnosis is to determine which cell type it is with biopsy
Sample the highest stage area as it is the most representative.
What is TNM classification?
Tumour Nodes Metastases T1a -> <10 mm tumour The larger the number, the most extensive it is. T3 invades organs - diaphragm/heart. N1/N2/N3 M1a - spread to other lung M1b - brain
What is SVCO?
Constriction of SVC caused by metastases.
Medical emergency.
What are the 3 main aetiology of lung cancer?
- smoking
- asbestos
- radiation (therapeutic, radon)
How do carcinoma develop from healthy cells?
Metaplasia -> dysplasia -> carcinoma in situ -> invasive carcinoma
What are the three types of non-small cell carcinoma? What percentage of lung cancers are non-small cell?
- Squamous cell carcinoma
- Adenocarcinoma
- Large cell carcinoma
80 % of lung cancers
How are the incidences of squamous cell carcinoma and adenocarcinoma changing?
Squamous cell carcinoma incidence is decreasing
Adenocarcinoma incidence is increasing
Where do squamous cell carcinomas and adenocarcinomas tend to arise?
Squamous cell carcinoma tends to arise near the mediastinum (airways). Ciliated epithelium changes to squamous epithelium because of repeated agression.
Adenocarcinoma tends to arise near the periphery. Forms from glandular epithelium..
Why has a precursor lesion for small cell lung carcinoma not been found?
Because small cell carcinoma grows too quickly and it metastasises early
How do the cells lining the airways change in squamous cell carcinoma?
The ciliated cells undergo metaplasia due to the chronic stimulation by cigarette smoke to become squamous cells
Which type of lung cancer is common in non-smokers?
Adenocarcinoma
Which types of lung caner are strongly associated with smoking?
Small cell carcinoma
Squamous cell carcinoma
Describe the cytological features of squamous cell carcinoma.
Large Nuclei
Keratin in cytoplasm
What is the precursor lesion for adenocarcinoma?
Atypical adenomatous hyperplasia = proliferation of atypical cells lining the alveolar walls. Increases in size and can eventually become invasive.
At what point does adenocarcinoma in situ become invasive adenocarcinoma?
When the cells develop a mutation to produce enzymes so that they can break down the stroma and become invasive. The breaking down of the stroma causes inflammation and leads to the formation of fibrous tissue.
Describe the cytological features of adenocarcinoma.
Adenocarcinoma shows glandular differentiation. They have big atypical nuclei with mucin globules
What are the two molecular pathways for adenocarcinoma and which one is associated with smoking?
Smoker = K ras mutation Non-smoker = EGFR (Epidermal Growth Factor Receptor) mutation/amplification
Why is it important to differentiate between the different pathways?
K ras mutation are not going to respond to targeted therapy (like Tarceva)
If EGFR, need to see if it is a responder or resistance mutation.
Responder can show almost complete regression with targeted therapies even with advanced disease.
What is large cell carcinoma?
Poorly differentiated tumours composed of LARGE cells.
No histological evidence of glandular or squamous differentiation.
Probably poorly differentiated adenocarcinomas or squamous.
Poorer prognosis.
What are the cytological features of small cell carcinoma?
Small, poorly differentiated cells (all effort put into proliferating, not differentiating, very fast proliferation). Grow so fast -> outgrow blood supply -> becomes necrotic.
Just nuclei with very small cytoplasm, kind of looks like lymphocytes.
Awful prognosis, worst type of lung cancer.
What type of receptor is EGFR and what is used to block this receptor?
Membrane receptor tyrosine kinase
-> tyrosine kinase inhibitor
What are paraneoplastic syndromes?
= systemic effect of tumour due to abnormal expression by tumour cells of factors (eg. hormones) not normally expressed by the tissue which the tumour arose.
State some endocrine paraneoplastic syndromes.
ADH
-> syndrome of inappropriate ADH
ACTH
Cushing’s syndrome
Parathyroid hormone-related peptides
Hypercalcaemia
Others
Calcitonin -> hypocalcaemia
Gonadotrophins -> gynaecomastia
