Pathology of lung cancers Flashcards
What is the incidence of lung cancer, compared to other cancers?
3rd most common cancer
What is the relative mortality of lung cancer?
Highest mortality rate of all cancers
What is the 5 year survival rate for someone diagnosed with lung cancer?
9.8%
What is the main cause of lung cancer?
Smoking
What are the other causes of lung cancer, besides smoking?
Asbestos
Environmental radon + other forms of background radiation
Occupational exposure - chromates, hydrocarbons, nickel etc
Air pollution (urban environment)
Pulmonary fibrosis
Passive smoking
What percentage of lung cancers are attributable to tobacco?
> 85%
What percentage of smokers get lung cancer?
10%
Roughly how long does it take after quitting smoking, for the risk of developing cancer decrease to ‘normal’?
15+ years
variable
Cigarettes contain over 400 chemicals, of which 60ish are carcinogenic
What are the 2 main groups of chemicals that are carcinogenic?
N-nitrosamines
Polycyclic aromatic hydrocarbons
What two types of lung cancers are associated with the chemicals found in cigarettes?
Adenocarcinomas
Squamous cell carcinomas
Which chemical group causes adenocarcinomas?
N-nitrosamines
What chemical group causes squamous cell carcinomas?
Polycyclic aromatic hydrocarbons
What area of the lungs are you more likely to find adenocarcinomas in?
Peripheries
Transformation of what type of cell gives rise to adenocarcinomas?
Bronchioalveolar epithelial stem cells
Where would you tend to find squamous cell carcinomas?
Central lung airways
nearer to the hilla
What is the multi-hit theory of carcinogenesis?
Must have at least 3 - 6 ‘hits’ (genetic mutations/alterations) of specific genes in order for a cancer to be able to form/grow
These must happen in a specific order
Specific ‘key driver mutations’ must happen in order for adenocarcinogenesis to take place
What genes most commonly mutate to allow this?
KRAS - 35%
EGFR - 15%
BRAF, HER2 - 1-2%
ALK - 2%
ROS1 - 1%
What 4 adenocarcinoma oncogenes have targeted treatments available in the UK?
EGFR
ALK
ROS1
BRAF
Why are there not really any targeted oncogene treatments for Squamous cell carcinomas?
SCC has very few addictive oncogenes
Not really any suitable targets
What are the 4 main types of carcinomas of the lung?
Adenocarcinoma
Squamous cell carcinoma
Small cell carcinoma
Large cell carcinoma
The frequency of squamous and small cell carcinomas has ______ in recent years
Plateaued
The frequency of adenocarcinomas has _______ in recent years
Risen
Why is primary lung cancer described as “generally fatal” whereas lung cancer from metastasis has higher survival rates?
Lung cancer is generally asymptomatic until later stages
If primary, theres a good chance the person won’t know until it’s too late
Metastasis to the lungs is common, so if someone already has cancer then it is ‘looked for’ and can often be found in earlier stages of development
What are the main local effects of lung cancer?
Bronchial obstruction
Pleural effects
Direct invasion
Lymph node metastasis