Symptoms from a lung cancer are produced by local bronchial irritation and invasion, bronchial obstruction with distal pneumonitis, invasion of local chest wall and mediastinal structures. Metastatic disease and para-neoplastic symptoms can mimic the symptoms of a plethora of other diseases. Therefore lung cancer, the modern “great imitator” should always be kept in mind when treating any medical condition in the at-risk group.

The classic symptoms of lung cancer are haemoptysis, cough, dyspnoea, chest pain and recurrent or persistent chest infections. Unfortunately lung cancers tend to occur in elderly smokers, all of whom have a “smoker’s cough” and frequent bouts of “bronchitis” with associated sputum production and frequently haemoptysis. Many have breathlessness due to emphysema, and chest pain due to ischaemic heart disease. The difficulty for the primary care physician is to determine which of these exacerbations is due to lung cancer. Furthermore, by the time a lung cancer has become symptomatic with the above symptoms, it is frequently incurable. Most patients who have curable tumours at the time of presentation have had an incidental chest X-ray for preoperative assessment for another condition or an insurance medical examination, or have had one of the above danger symptoms during a chest infection unrelated to the tumour. Therefore it is important to emphasise and encourage such “pseudo-screening” particularly in the high risk group: the middle aged smoker.

Locally advanced lung cancer can present with a number of symptoms due to invasion or impaction on other organs in the chest. Superior vena caval obstruction is due to mediastinal nodes encompassing the SVC and usually the azygous vein. The patient is plethoric with enlarged subcutaneous veins in the upper trunk and a persistently raised, non-fluctuating jugular venous pressure. When advanced the patient cannot lie flat because of a breathless “drowning sensation”. Subcarinal or inferior mediastinal nodes can also impinge on the oesophagus causing dysphagia and aspiration pneumonitis. Hoarseness is a sign of recurrent laryngeal nerve palsy. It is more common on the left due to tracheo-bronchial and aorto-pulmonary window nodes invading the nerve as it loops under the ligamentum arteriosum. Hoarseness may also be due to direct invasion of the vagal nerves by an apical tumour or cervical node metastases. Similarly the phrenic nerve may be involved with mediastinal tumour invasion particularly as the nerve crosses the pericardium. A raised hemi-diaphragm is the sign on chest X-ray though this can be produced by lobar atelectasis. Confirmation of nerve palsy can be made by fluoroscopic examination of the diaphragm on inspiration. The brachial plexus, when invaded by a tumour of the superior sulcus in the apex of the chest, produces the “Pancoast syndrome” with pain radiating to the shoulder and inner aspect of the arm, a Horner’s syndrome due to sympathetic chain invasion and subclavian vascular compression or thrombosis. Like other nerve invasion signs this syndrome usually indicates inoperability though the use of pre-operative radiotherapy followed by surgery can result in long term survival.

As lung cancers can be present for many years and grow to a considerable size before they become symptomatic many actually present with metastatic disease. The adrenal, liver, bone and contralateral lung are the common sites of metastasis. Lung cancer is in more ways the modern “great imitator”, in that secondary disease can cause symptoms in many organ systems.