Causes and incidence of Bronchogenic carcinoma
(no definite aetiology)
• Male > female
• Peak incidence occurs between ages 55 and 65 years.
• Predisposing factors:
• The major cause is tobacco use particularly cigarette smoking
• 3,4 benzpyrine is the carcinogenic substance especially if combined with asbestos.
• Air pollution (coal combustion, cadmium and radon).
• Occupation inhaled substances e.g asbestos, nickel and arsenic.
• Radiation e.g atomic bomb survivors, uranium miners.
• Genetic mechanism e.g dominant oncogenes and loss of tumour suppressor genes.
The risk is increased 40 times fold for man smoking two packs /d. for 20 years .
Pathology
1- Central or hilar type in a main bronchus, it invades the mediastinum early
2- Peripheral in small bronchus, it invades pleura early
3- Pancoast tumour, it is apical and invades the thoracic inelt early.
• Naked eye appearance : Fungating mass - Malignant ulcer - Infiltrative type
• Microscopic:
WHO classification
Methods of Spread of Bronchogenic carcinoma
• Direct : lung, pleura, mediastinum, brachial plexus, sympathetic chain and phrenic nerve.
• Lymphatic spread : - Hilar & mediastinum, then cervical L.N.
-Retrograde lymphatic ==> (lymphangitis carcinomatosa) ==> cor pulmonale
• Haematogenous : Bones, liver, brain
Bronchoalveolar cell carcinoma (Bronchiolar carcinoma) arising in the terminal bronchioloalveolar regions accounts for 1-2% of lung tumors.
It may be a peripheral solitary nodule or diffuse nodular lesion. It occurs in men and women equally and
usually not associated with smoking.
It may be associated with expectoration of a large volumes of mucoid sputum.
Source : Bronchogenic Carcinoma causes, pathology, classification and spread