Left chest pain is a symptom, which does not necessarily mean lung cancer. CT, pulmonary artery CTA, etc. can help to make a clear diagnosis. 3, large vessel diseases, the most common is aortic coarctation, the patient can also appear left chest pain, but the patient is accompanied by relatively high blood pressure, check the aortic CT can help to make a clear diagnosis. 4, the chest wall itself, such as intercostal neuralgia, costochondritis, muscle pain can appear left chest pain, the application of pain medication can help to relieve pain.