• Lung cancer

    by  • 02/06/2013 • Respiratory

    Lung cancer

    Definition

    1. Bronchial carcinoma accounts for 95% of all primary tumours of the lung.
    2. Alveolar cell carcinoma accounts for 2% of lung tumours.

     

    Divided into:

    NON-SMALL-CELL CARCINOMA (NSCLC)

    1. 1. Squamous or epidermoid carcinoma 40%
    2. Most likely to be central
    3. S’s = Squamous, smoking, slow, sentral!

     

    1. 2. Adenocarcinoma
    2. Arise from MUCOUS cells
    3. Commonly invades pleura or mediastinal lymph nodes
    4. Metastasise to brain and bone
    5. NOT linked to smoking.
    6. Most likely to be peripheral

     

    1. 3. Large cell carcinoma
    2. Metastasise early

     

    1. 4. Bronchoalveolar cell carcinoma

     

    Occur as:

    1. Peripheral solitary nodule
    2. Diffuse nodular lesions of multicentric origin
    3. Copious mucus coughed up

     

    SMALL CELL CARCINOMA (SCLS) = Oatcell carcinoma

    1. Arises from endocrine cells = Kulchitsky cells
    2. May produce ACTH or ADH
    3. Spreads early
    4. 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
    Carcinoid 0.8
    Sarcoma 0.1
    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.

    Other: HAMARTOMAS

    1. Benign, focal neoplasms
    2. 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.
    3. COWDEN syndrome: multiple systemic hamartomas (lungs, thyroid, CNS), genetic. Can be fatal.
    4. Thymoma (tumour originating from epithelial cells of thymus) linked to MG!

    Incidence

    1. 3rd most common cause of death in the UK
    2. 36,000/y
    3. Peak incidence 70-80years
    4. Social deprivation = highest incidence and worst outcome. Smokers!
    5. M>F (3-4:1)

     

    Aetiology – cause, risk factors

    1. 90% due to Smoking – contains over 60 known carcinogens (?5% due to passive smoking)
      1. o Lifelong smoker has 16% risk of lung cancer at 75
    2. 5% due to Radon gas
    3. Asbestos
    4. Viruses
    5. 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.

    Metastatic complications

    1. Bony metastases are common = pain and pathological fractures.
    2. Brain mets = change in personality, epilepsy or as a focal neurological lesion.

     

    Lung cancer, main sites for distant metastases

    BLAB

    Bone

    Liver

    Adrenals

    Brain

     

    Tumour spread

    1. Carcinoma of the apex can erode ribs (‘rib notching’) and involve lower brachial plexus
      1. Severe pain in shoulder and down inner surface of the arm = PANCOASTS TUMOUR
    2. Involve sympathetic ganglion
      1. HORNERS SYNDROME = unilateral pupil constriction and ptosis
    3. Hilar tumours may involve recurrent laryngeal nerve
      1. Unilateral vocal cord paresis with hoarseness and bovine cough
    4. Invade phrenic nerve
      1. Paralysis ipsilateral hemidiaphragm
    5. Involve oesophagus
      1. Progressive dysphagia
    6. Involve pericardium
      1. Pericardial effusion and dysrhythmias
    7. Superior vena caval obstruction
      1. Early morning headache, facial congestion and oedema.
      2. Jugular veins are distended

     

    Increased risk in fibrosing alveolitis and Silicosis

    Diagnostic/Investigation

    1. Chest xray
    2. By the time lung cancer is causing symptoms, it will almost always be visible on CXR
    3. Lateral views are useful to assess the hilum and masses behind the heart.

     

    1. Computed tomography
    2. Useful for:
    3. o Identifying disease in the mediastinum, such as enlarged lymph nodes
    4. o Local spread of tumour
    5. o Identifying secondary spread of carcinoma to the opposite lung by detecting masses too small to be seen on chest x-ray

     

    1. Fibreoptic bronchoscopy
    2. Used to define the bronchial anatomy and to obtain biopsy and cytological specimens.

     

    1. Percutaneous aspiration (FNAC) and biopsy
    2. Peripheral lung lesions can’t be seen by fibreoptic bronchoscopy and sample may be obtained by direct aspiration or biopsy

     

    Spread – genetics

    Genetic changes:

    Tumour suppressor gene (switched off):

    3p, 9p, p16, 13q, 17P, P53!

    Activation of oncogenes (switched on):

    EGFR, K-Ras, Myc

     

    Treatment/management

    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.

    1. 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.
    2. If not operable – early RT may be curative if slow-growing squamous carcinoma.
    3. RT can reduce bone pain/haemoptysis/SVC obstruction in short term.

     

    SCLC: CT immediately.

    Palliative Care: prednisolone, morphine

    1. 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
    2. Aim to keep trachea patent – reduce cough/SOB/RF…

     

    Prognosis

    20% of patients are alive 1 year after diagnosis

    6-8% are alive 5 years after diagnosis

    Differential diagnosis

    1. Not all shadows are malignant
    2. Benign tumours and cysts
    3. Infection, especially tuberculosis, lung abscess, pneumonia, Aspergilloma
    4. Pulmonary infarct due to embolus
    5. Granulomatous disease such as sarcoidosis, Wegeners
    6. Loculated fluid in an inter-lobar fissure 
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