- Bronchial carcinoma accounts for 95% of all primary tumours of the lung.
- Alveolar cell carcinoma accounts for 2% of lung tumours.
NON-SMALL-CELL CARCINOMA (NSCLC)
- 1. Squamous or epidermoid carcinoma 40%
- Most likely to be central
- S’s = Squamous, smoking, slow, sentral!
- 2. Adenocarcinoma
- Arise from MUCOUS cells
- Commonly invades pleura or mediastinal lymph nodes
- Metastasise to brain and bone
- NOT linked to smoking.
- Most likely to be peripheral
- 3. Large cell carcinoma
- Metastasise early
- 4. Bronchoalveolar cell carcinoma
- Peripheral solitary nodule
- Diffuse nodular lesions of multicentric origin
- Copious mucus coughed up
SMALL CELL CARCINOMA (SCLS) = Oatcell carcinoma
- Arises from endocrine cells = Kulchitsky cells
- May produce ACTH or ADH
- Spreads early
- Normally inoperable
|Frequency of histological types of lung cancer|
|Histological type||Frequency (%)|
|Non-small cell lung carcinoma||80.4|
|Small cell lung carcinoma||16.8|
|Unspecified lung cancer||1.9|
Patients are staged according to the TNM classification for non-small-cell cancer but small-cell cancer is treated according to whether it is limited or extensive.
- Benign, focal neoplasms
- 75% of all benign lung masses, form in connective tissue, in periphery of lung only, asymptomatic, ‘pop-corn’ appearance on CXR, can be surgically resected.
- COWDEN syndrome: multiple systemic hamartomas (lungs, thyroid, CNS), genetic. Can be fatal.
- Thymoma (tumour originating from epithelial cells of thymus) – linked to MG!
- 3rd most common cause of death in the UK
- Peak incidence 70-80years
- Social deprivation = highest incidence and worst outcome. Smokers!
- M>F (3-4:1)
Aetiology – cause, risk factors
- 90% due to Smoking – contains over 60 known carcinogens (?5% due to passive smoking)
- o Lifelong smoker has 16% risk of lung cancer at 75
- 5% due to Radon gas
- Particulate matter
P/c: Cough, haemoptysis, chest pain/infection, malaise, weight loss, dyspnoea, hoarseness, supraclavicular LNs, pleural effusion/lobar collapse, bony tenderness (mets), hepatomegaly.
Paraneoplastic symptoms: Cushings syndrome (excessive cortisol/ACTH produced by tumour), clubbing, neuromuscular syndrome = Eaton-Lambert (autoimmune condition: voltage gated Ca2 channels on pre-synaptic membrane releases LOWER amounts of Ach. Motor power increases with use), hypercalcaemia (PTH-like hormone), SIADH = hyponatriemia (water retention), thrombotic events.
- Bony metastases are common = pain and pathological fractures.
- Brain mets = change in personality, epilepsy or as a focal neurological lesion.
Lung cancer, main sites for distant metastases
- Carcinoma of the apex can erode ribs (‘rib notching’) and involve lower brachial plexus
- Severe pain in shoulder and down inner surface of the arm = PANCOASTS TUMOUR
- Involve sympathetic ganglion
- HORNERS SYNDROME = unilateral pupil constriction and ptosis
- Hilar tumours may involve recurrent laryngeal nerve
- Unilateral vocal cord paresis with hoarseness and bovine cough
- Invade phrenic nerve
- Paralysis ipsilateral hemidiaphragm
- Involve oesophagus
- Progressive dysphagia
- Involve pericardium
- Pericardial effusion and dysrhythmias
- Superior vena caval obstruction
- Early morning headache, facial congestion and oedema.
- Jugular veins are distended
Increased risk in fibrosing alveolitis and Silicosis
- Chest xray
- By the time lung cancer is causing symptoms, it will almost always be visible on CXR
- Lateral views are useful to assess the hilum and masses behind the heart.
- Computed tomography
- Useful for:
- o Identifying disease in the mediastinum, such as enlarged lymph nodes
- o Local spread of tumour
- o Identifying secondary spread of carcinoma to the opposite lung by detecting masses too small to be seen on chest x-ray
- Fibreoptic bronchoscopy
- Used to define the bronchial anatomy and to obtain biopsy and cytological specimens.
- Percutaneous aspiration (FNAC) and biopsy
- Peripheral lung lesions can’t be seen by fibreoptic bronchoscopy and sample may be obtained by direct aspiration or biopsy
Spread – genetics
Tumour suppressor gene (switched off):
3p, 9p, p16, 13q, 17P, P53!
Activation of oncogenes (switched on):
EGFR, K-Ras, Myc
Involves several different modalities and is best planned by a multidisciplinary team
NSCLC: resect if operable (maybe curative = good outcome), then RT with CT adjunct.
- Radiation pneumonitis (defined as an acute infiltrate precisely confined to the radiation area and occurring within 3 months of radiotherapy) develops in 10-15% of cases.
- If not operable – early RT may be curative if slow-growing squamous carcinoma.
- RT can reduce bone pain/haemoptysis/SVC obstruction in short term.
SCLC: CT immediately.
Palliative Care: prednisolone, morphine
- Laser therapy, endobronchial irradiation and trachobronchial stents: Used in palliation of inoperable lung cancer in selected patients with tracheobronchial narrowing from intraluminal tumour or extrinsic compression
- Aim to keep trachea patent – reduce cough/SOB/RF…
20% of patients are alive 1 year after diagnosis
6-8% are alive 5 years after diagnosis
- Not all shadows are malignant
- Benign tumours and cysts
- Infection, especially tuberculosis, lung abscess, pneumonia, Aspergilloma
- Pulmonary infarct due to embolus
- Granulomatous disease such as sarcoidosis, Wegeners
- Loculated fluid in an inter-lobar fissure