In the vast majority of cases, pain in the left scapular suture is not due to lung cancer. Some patients think that in the middle of the scapular suture is the lung, but this is actually not the case. The scapula is part of the shoulder joint, which is covered by the ribs, intercostal muscles, pleura and other structures below it, and it is relatively far from the lung, even in the area of the suture. If a patient has lung cancer, he or she will not show pain here, but will first show coughing up blood and have chest pain during coughing. Pain in this part of the scapular suture is often caused by the following reasons: 1. It may be caused by muscle spasm here, which is often seen when the patient has a bad sitting posture, which over time will cause the muscles around the left scapula to produce 2. It may be caused by fasciitis in the back of the shoulder, which is often caused by prolonged exposure to cold or old injury, resulting in inflammation of the deep fascia and pain in this area. 3.