Lung cancer may cause shoulder pain and arm pain under the following conditions: 1. bone metastasis, bone is a common metastasis site of lung cancer, when cancer cells metastasize to the scapula (and) or humerus will cause obvious pain, which is mainly caused by cancer cells destroying bone and stimulating periosteal nerves. 2. tumor compression or lymph node metastasis compressing nerves causing pain, the tumor in the lung tip may compress the shoulder or axillary nerve and cause pain. The metastasis of lymph nodes in the supraclavicular or axillary area of lung cancer may lead to enlargement of lymph nodes in the corresponding area and compression of surrounding nerves, which may also cause pain in the shoulder and arm. 3. Neuroendocrine hormones cause osteoporosis. .