0514 - Lung Cancers Flashcards
Discuss the epidemiology of lung cancer
4th most commonly diagnosed cancer, and 5th in Australia, but kills more than any other cancer.
Tobacco is the world’s single most avoidable cause of death
5 year survival 14%
Risk factors - Smoking, radon asbestos, air pollution
What are some major complications of smoking?
Cancers
Atherosclerosis and cardiovascular disease
Respiratory disease - Asthma, Chronic Bronchitis, Emphysema, Respiratory Bronchiolitis.
What determines the relationship between smoking and lung cancer? (5 factors)
Amount of smoking
Tendency to inhale
Duration of smoking
Age of initiation of smoking
Expressed in pack years.
What are some changes that occur in the lung as a result of smoking?
Inflammation
Enlarged air spaces (emphysema) leading to bullae
Carbon pigment (anthracosis)
Fibrosis and scarring
Carcinoma.
How does tobacco cause emphysema?
Reactive oxygen species released by tobacco smoke leads to direct tissue damage and inactivation of antiproteases (functional alpha-1 AT deficiency). This leads to increased neutrophil elastase which contributes to the tissue damage.
How does smoking cause lung squamous carcinoma? (Like adenoma-carcinoma sequence in colon)
Normal pseudostratified ciliated columnar epithelium undergoes metaplasia to squamous with orderly maturation.
Dysplasia results (no orderly maturation), becoming carcinoma in situ.
How does lung adenocarcinoma form?
Normal lung tissue develops atypical adenomatous hyperplasia in response to insult.
Progresses to bronchiolo-alveolar carcinoma (adenocarcinoma in situ, preinvasive)
Invades through basement membrane with potential to metastasise.
What two types of lung carcinoma are most associated with smoking? Which is weakest?
Squamous and small cell carcinomas strongly associated.
Adenocarcinoma weakly associated - often associated with non-smokers.
What is the broad classification of lung neoplasms? (WHO)
Based on cell type
Most important
- Squamous cell carcinoma
- Small cell carcinoma
- Adenocarcinoma
Less important
- Large cell carcinoma
- Adenosquamous carcinoma
- Sarcomatoid carcinoma
- Carcinoid tumour
- Salivary gland tumours
What is the general classification for lung cancer and why? (the two types)
Small cell (15%) vs non-small cell (85%)
Treatment and prognosis are different for small cells than for other lung cancers.
(Small cell rapidly metastasises, so can’t have surgery and poor prognosis)
Describe adenocarcinoma of the lung
Generally peripheral and slow growing. But early metastasis.
F>M
Histology - can grow along alveolar walls with extensive glands/mucin producing tissue.
Describe squamous carcinoma of the lung.
Most common, and generally central. Large tumours can have a central cavity (necrosis)
M>F
Central - often spreads to the hilar lymph nodes.
Histologically - looks like all SCCs with keratin pearl formation and intercellular bridges.
Describe small cell carcinoma of the lung.
Centrally located, often metastasize before diagnosis, with primary difficult to find.
Rapid growth, deriving from neuroendocrine cells. Paraneoplastic syndromes are often the PC.
Require chemotherapy rather than surgery.
Histological, numerous small cells with moulding and minimal cytoplasm, ‘salt and pepper chromatin’.
What are the cell types of normal bronchial mucosa?
4 cell types
- Ciliated columnar
- Goblet cells
- Neuro-endocrine
- Basal cells.
Describe large cell carcinoma of the lung
Often peripheral, large cells with large nuclei, lacking differentiation.
Giant cell or spindle cell variants
Poor prognosis due to early metastasis.
