Bronchial carcinoma is the most common malignant tumor worldwide, with around 1.4 million deaths annually.
- It is the third most common cause of death in the UK after ischaemic heart disease and cerebrovascular disease and is now the commonest cause of cancerrelated
death in both men and women.
- Rates are declining in men but still increasing overall reflecting increasing incidence in women.
- The ratio in men-to-women is now 1.2 : 1
Cigarette smoking (including passive smoke exposure) accounts for >90% of lung cancer. There remains a higher incidence of bronchial carcinoma in urban compared with rural areas, even when allowance is made for cigarette smoking. Other etiological factors include:
- Environmental: radon exposure, asbestos, polycyclic aromatic hydrocarbons and ionizing radiation. Occupational exposure to arsenic, chromium, nickel, petroleum products and oils
- Host factors: pre-existing lung disease such as pulmonary fibrosis; HIV infection; genetic factors.
Legislative control over smoking in public places in many parts of the world has been introduced to reduce ill health related to cigarette smoke.
Historically, lung cancers are broadly divided into small cell carcinoma and non-small cell carcinoma based upon the histological appearances of the cells seen within the tumour.
This distinction is necessary with respect to the behaviour of the tumour, providing prognostic information and determining best treatment. Non-small cell carcinoma is further divided into a number of cell types (adenocarcinoma, squamous cell carcinoma, large cell carcinoma, large cell neuroendocrine.
The presentation and clinical course vary between the different cell types. Symptoms and signs may vary depending on the extent and site of disease. Common presenting features can be divided into those caused by direct/local tumour effects, metastatic spread and non-metastatic extra-pulmonary features.
- Cough: this is the most commonly encountered
symptom in lung cancer. Because evidence suggests
this symptom is neglected by both patients and
healthcare professionals, campaigns in the UK have
highlighted the ‘three week cough’ as a symptom that
merits a chest X-ray.
- Breathlessness: central tumours occlude large airways resulting in lung collapse and breathlessness on exertion. Many patients with lung cancer have co-existent COPD which is also a cause of breathlessness.
- Haemoptysis: coughing up fresh or old blood due to tumour bleeding into an airway.
- Chest pain: peripheral tumours invade the chest wall or pleura (both well innervated), resulting in sharp pleuritic pain. Large volume mediastinal nodal disease often results in a characteristic dull central chest ache.
- Wheeze: monophonic when due to partial obstruction of an airway by tumour.
- Hoarse voice: mediastinal nodal or direct tumour invasion of the mediastinum results in compression of the left recurrent laryngeal nerve.
- Nerve compression: Pancoast tumours in the apex of the lung invade the brachial plexus causing C8/T1 palsy with small muscle wasting in the hand and weakness as well as pain radiating down the arm. An associated Horner’s syndrome due to compression of the sympathetic chain with classic features of miosis, ptosis
and anhidrosis also occurs.
- Recurrent infections: tumour causing partial
obstruction of an airway results in post-obstructive
- Bronchial carcinoma can also directly invade the
phrenic nerve, causing paralysis of the ipsilateral
hemidiaphragm. It can involve the oesophagus,
producing progressive dysphagia, and the pericardium,
resulting in pericardial effusion and malignant
- Superior vena caval obstruction
- Tracheal tumours present with progressive dyspnoea and stridor. Flow volume curves show dramatic reductions in inspiratory flow.
Bronchial carcinoma commonly spreads to mediastinal, cervical and even axillary or intra-abdominal nodes. In addition, the liver, adrenal glands, bones, brain and skin are frequent sites for metastases:
- Liver: common symptoms are anorexia, nausea and weight loss. Right upper quadrant pain radiating across the abdomen is associated with liver capsular
- Bone: bony pain and pathological fractures as a result of tumour spread occur. If the spine is involved, there is a risk of spinal cord compression, which requires urgent treatment.
- Adrenal glands: metastases to the adrenals do not usually result in adrenal insufficiency and are usually asymptomatic.
- Brain: metastases present as space-occupying lesions with subsequent mass effect and signs of raised intracranial pressure. Less common presentations include carcinomatous meningitis with cranial nerve defects, headache and confusion.
- Malignant pleural effusion: this presents with breathlessness and is commonly associated with pleuritic pain.