Resp 6 - Respiratory Pathology Flashcards
What is mutational compensation?
House keeping genes (p53) induces apoptosis - prevents immortal cancer cells
What are the clinical features of lung cancer?
- Haemoptysis.
- Unexplained/persistent cough/chest pain/chest signs/dyspnoea/hoarseness/finger clubbing
- Nail bed should be less than 180 degrees.
First, we determine if its small cell or non-small cell cancer. Then, TNM classification is used. Explain how TNM classification works.
- Tumour (1-4)- location, size and proximity to other organs. If tumour close to mediastinum or chest wall, it has a higher T staging,
- Nodes (1-4)- has it spread to lymph nodes
- Metastases - has it metastasised?
What can be used to sample a few cells of a tumour to be examined by pathologists?
Fine needle aspiration
How can PET scans be used for tumours?
Radiolabelled glucose given to patient. Radiolabelled glucose taken up by metabolically active tissues - show up very clearly (i.e. identify tumours)
What is the treatment algorithm for non-small cell lung cancer?
Diagnose -> Stage -> Test
Treatment based on cell type of tumour, extent of tumour, how fit the patient is.
Small lung cancers grow rapidly and metastasise early.
If the disease is advanced, give chemotherapy initially and try to minimise spread
What is the earliest point in time when you can diagnose lung cancer?
When the tumour is around 10mm
Most tumours diagnosed around 30mm
How many cases of lung cancer are there in the UK?
40,000
What factors are involved in diagnosing the lung tumour?
- Cell type
- Subgroup
- Molecular phenotype (for targeted treatments)
How many lobes are in the right and left lung?
Right = 3 lobes Left = 2 lobes
Name 5 contributors to lung cancer.
- Smoking
- Asbestos exposure
- Radiation
- Genetic predisposition
- Heavy metals
Describe benign lung tumours.
- Do not metastasise
- Can cause local complications (e.g. airway obstruction)
e.g. chondroma
Describe malignant lung tumours.
- Are able to metastasise
- Invade adjacent tissues
e.g. epithelial tumours
What are the 3 types of Non-small cell carcinomas?
1, Squamous cell carcinoma
- Adenocarcinoma
- Large cell carcinoma (uncommon)
What are features of small cell carcinoma?
Much worse prognosis. Its rare to find a small cell carcinoma - they grow rapidly and metastasise early.
What is the most common form of lung cancer amongst non smokers?
Adenocarcinoma (rising in incidence whereas squamous cell carcinoma is decreasing in incidence)
Where do squamous cell carcinomas tend to arise?
Where do adenocarcinomas tend to arise?
Squamous cell = near mediastinum
Adenocarcinoma = in the periphery
What is the general multistep pathway for carcinoma development?
- Metaplasia
- Dysplasia
- Carcinoma in situ
- Invasive carcinoma
Describe how a squamous cell carcinoma develops
Tends to occur in airways
- Cigarette smoke irritation causes epithelium to become tougher.
- Ciliated epithelium is delicate. Repeated exposure to smoke changes it to squamous epithelium.
- Lack of cilia means mucus stays in lungs - smokers cough
- Squamous epithelia acquire mutations which alters the normal pattern of growth - becomes carcinoma in situ as disordered dysplasia.
- Further mutations make it invasive - invades neighbouring tissues and lymphatics.
Traditionally, squamous epithelium carcinomas have been central but recently they are more peripheral. Why?
People have been inhaling the smoke more deeply.
The carcinomas spread distally in the lungs before spreading to lymph nodes.
What do irregular squamous cell cancers have?
Irregular cells have large nuclei and keratin in cytoplasmic,
Where does an adenocarcinoma come from?
Forms from glandular epithelium.
What is atypical adenomatous hyperplasia?
Proliferation of atypical cells lining the alveolar walls.
How do atypical adenomatous hyperplasia progress into an adenocarcinoma?
- Atypical adenomatous hyperplasia causes alveolar walls to thicken and be lined by atypical cells.
- Some of the atypical cells will grow larger but not invasive yet.
- Eventually, cells mutate. They form enzymes that breakdown stroma.
- Stromal breakdown forms fibrous scars and is accompanied by inflammation.
- Invasive adenocarcinoma can become invasive and breakdown elastin in the basement membrane - forming pink fibrous stroma.
