Pathology of lung cancers Flashcards
Is lung cancer the commonest cause of cancer death?
Yes
How many people in Scotland are diagnosed each year with lung cancer? Is it equal men/women?
Approx 5000, pretty much equal now men/women
What are the causes of Lung Cancer?
Tobacco! Environmental radon Occupational exposure - Chromates/hydrocabons/nickel Air pollution/urban environment Radiation Pulmonary fibrosis
What percentage of lung cancers can be attributed to tobacco?
85%
What percentage of smokers will get lung cancer?
10%
Is there a safe smoking threshold?
No
What is How long does it take for an ex smokers risk factor to return to standard level?
And why?
A long time (15+ years)! Because the genetic damage that is caused by tobacco carcinogens takes a long time to be flushed out of the epithelial cell population.
What % of UK people smoke in the UK?
20-30%
Is tobacco and smoking in China/S, SE Asia/South America increasing or decreasing ?
Increasing!! Amount of lung cancer is shooting up.
How many recognised carcinogens in a cig?
60+
What are the main 2 families of carcinogens present?
Polycyclic aromatic hydrocarbons and N-Nitrosamines
What type of cancers are most likely to appear after polycyclic aromatic hydrocarbons ?
Central part of lung - in the bronchi - squamous/small cell carcinoma
From unfiltered toacco products - more common 50/60 years ago.
What type of cancers are most likely to appear after N-nitrosamines?
More prone to cause adenocarcinomes (especially more in women than men)
How do the carcinogens affect the epithelia? How many genomic alterations?
3-12 key genomic alterations in the stem cell epithelia ( 2 populations of epithelia) , usually in a particular sequence to keep the cells alive with the mutations.
What are pro-carcinogens?
They are substances that aren’t carcinogens when we inhale/digest them, but then they are processed by our bodies to become carcinogens
What varies so we develop different risk of developing carcinogens?
Genetics! We inherit different isoenzymes of metabolising enzyme families
Where are the 2 stem cells populations?
In the larger areas of the bronchi and in the peripheral lung epithelium (small bronchioles and alveoli)
What are the pathways for aleveolar/bronchi cancers
Alveoli - Adenocarcinoma:
Bronchioloalveolar epithelial stem cells transform - Atypical Adenomatous Hyperplasia - develop into adenocarcinomas - Adenocarcinoma in Situ - Invasive adenocarcinoma
Bronchi - Squamous cell carcinoma:
Bronchial epithelial stem cells transform - Bronchial basal cell
Hyperplasia - Squamous dysplasia and carcinoma in situ - Invasive
squamous cell carcinoma
What can be other causes for masses in the lung?
Consolidation/fibrosis from pneumonia,
What are the 4 main types of primary lung cancer?
Squamous cell carcinoma (40% decreasing)
Adenocarcinoma (41% increasing)
Small cell carcinoma (15%)
Large cell carcinoma (4%)
Which are the most prevalent? And in which genders, due to rise in N-nitrosamines?
Adenocarcinomas and squamous cell carcinomas are most prevelant.
Adenocarcinomas are on the rise, especially in women (as they have increased in smoking and potentially have a higher susceptibility) and due to the increasing amount N-nitrosamines in tobacco.
Small cell carcinoma is related to which carcinogen group?
Polycyclic aromatic hydrocarbons
Is non small cell carcinoma a biological entity?
Nope, its a group of lng cancers that aren’t small cell carcinomas
If presenting as lung cancer has it spread?
Yes, there are rarely any symptoms in early stage lung cancer, so if someone presents as lung cancer the chances are that it is quite late and it has already spread.
