Pathology Flashcards
What is the greatest cause of lung cancer?
smoking
also non smokers
- asbestos (+smoking 50 fold increase)
- radiation
- genetic predisposition
- heavy metals
p53 gene are housekeeping genes that stop growth of cell to immortal cell line by causing apoptosis - BUT these p53 genes are damaged by smoking
also increasing effect of oncogenes
What are clinical features of lung cancer?
haemoptysis
finger clubbing (angle between nail and nail bed >180)
nicotine staining
cachexia
unexplained/persistent for more than 3 wks
- cough
- chest/shoulder pain
- chest sgins
- dyspnoea
- hoarseness
CXR urgent referral
- large mass in R lower lobe
What are types of lung cancer, how are they classified for diagnosis?
CELL TYPE
non small cell
small cell
SUBTYPE
then further classification (pathology from biopsy)
MOLECULAR PHENOTYPE
- non small cell lung cancer (if PDL-1 over 50% then eligible for immunotherapy)
- adenocarcinoma (look for common mutations for targeted treatment)
How to stage lung cancer?
TNM classification
tumour
- size (10mm T1, 30 T2)
- location (if spread - T3)
lymph node (N0-3) - hilar, mediastinal and contralateral lymph nodes
metastasis (M0/1)
- to brain? bone? liver?
- bone metastases meaning local treatment inefficient
What is the typical first step for staging of lung cancer? Rest of pathway?
CXR
CT THORAX with diagnosis and staging at same time
FDG-PET-CT
- radio labelled glucose taken up by active heart and brain
- if taken up by mediastinal lymph nodes indicates metastatic lung cancer
CT biopsy (risk of pneumothorax), endobronchial US
MRI brain - more detail as not clear on PET (high uptake of glucose)
PFTS
patients may also get non metastatic manifestations of lung cancer (wrist pain/ankle pain - e.g. release PTH that causes hypercalcaemia)
What is the difference in pathway for small and non small cell lung cancers?
non small cell - slow growing, try to remove and adjuvant radio/chemotherapy
but if spread to mediastinal lymph nodes give radiotherapy/chemotherapy combination with surgery
small cell - rapidly dividing, treatment based on chemotherapy
What is the problem with lung metastasis?
tumours spread before we can see them
diagnosis so late that time remaining for survival is minimal
CT screening
stop smoking
What is the epidemiology of lung cancer?
4th common cause of all mortality in west
death in 80% cases, 5 year survival/cure rate less than 6%
Diameter of tubular system in lungs?
bronchi >1mm
bronchiole <1mm
small airways <2mm
What are the main types of lung cancer?
BENIGN tumour (can cause obstruction)
MALIGNANT
non small cell - everything else, squamous cell carcinoma (20-40%), adenocarcinoma (20-40%), large cell carcinoma uncommon
early stage 60% 5 yr survival, late stage 5% 5 yr survival, 20-30% tumours early stage and can be resected, less chemosensitive
small cell (20%) - undifferentiated, advanced, aggressive
What is squamous cell carcinoma?
- cigarette smoke irritates ciliated epithelium in the lung upper airways and this changes cell type by metaplasia as mutations accumulate (lose cilia)
- invade stroma
What is adenocarcinoma?
MORE COMMON IN NON SMOKERS, spread more early
tumour of glandular epithelium in periphery, terminal airways, interstitium
- atypical cells at start that increase in size and become invasive
- before invasive = adenocarcinoma in situ (excise early lesions to avoid metastasis)
What are molecular pathways in adenocarcinoma?
smoker
- K ras mutation
non smokers
-EGFR mutation
What is large cell carcinoma?
- poorly differentiated tumours
What is small cell carcinoma?
- 20-25% tumours central near bronchi - close association with smoking - most present with advanced disease - respond well to chemotherapy/radiotherapy
survival 2-4 mths intreated, 10-20 treated with chemoradiotherapy
