The most common cause of shoulder pain is chronic strain of the ligaments and muscles in the shoulder, not lung cancer. Lung cancer accounts for only a small portion of the reasons. If a patient has lung cancer, it can spread to the shoulder, or the lung cancer itself can produce a type of referred pain, which can cause shoulder pain. To determine the cause, it is necessary to go to the hospital for an X-ray of the shoulder joint or a plain chest film, as well as an MRI of the shoulder joint, to clarify the cause of the shoulder pain. If the pain is solely due to the muscles or ligaments in the shoulder, it can be relieved through conservative treatments such as massage, acupuncture, electrotherapy, and magnetotherapy.