The symptoms caused by lung cancer may be due to: 1) the tumour itself; 2) the tumour extension inside the chest; 3) the metastatic spread of the tumour, and 4) non-metastatic systemic manifestations (these are called paraneoplastic symptoms and can appear in any part of the body, for example, an increased body temperature).

Cough is the most frequent symptom. Other symptoms can be shortness of breath (dyspnoea), blood in sputum (haemoptysis), fever, fatigue or loss of weight.

When the tumour involves other tissues it could result in: bigger lymph nodes (for example, on the neck), shoulder and arm pain or chest pain (due to nerve involvement), difficulty in speaking or dysphonia (due to paralysis of a vocal cord), difficulty in swallowing (when the tumour compresses the oesophagus).

If the cancer spreads to another part of the body, symptoms and signs may appear in the affected systems, for example, neurological or bone symptoms.

But sometimes a lung nodule is found by chance in an imaging test in a person without symptoms or signs. In this case, it will be necessary to study the nodule to know whether it is a cancer or not.