Shoulder pain caused by cancer is different from ordinary shoulder pain in terms of pain cause, pain location, pain sensation, accompanying symptoms and relief. Patients can make preliminary judgment based on the following, but ultimately, it is recommended to actively seek medical advice for diagnosis: 1. Pain cause: Shoulder pain caused by cancer may be caused by malignant tumors such as breast cancer, lung cancer and stomach cancer, which cause pain due to cancer cells infiltrating the tissues around the shoulder. Ordinary shoulder pain is usually caused by long time heavy physical labor, traumatic impact or cervical spondylosis, resulting in damage to shoulder muscles and nerves. 2. Pain location: Cancer can cause pain in several small areas of the shoulder, which is determined based on the infiltration site of cancer cells, such as pain in the scapula, armpit, clavicle and ribs, and cancer in the cervical spine can also stimulate the nerves causing pain in the shoulder and cervical spine. In contrast, ordinary shoulder pain has a fixed pain site based on strained muscles. 3. Pain sensation: Shoulder pain caused by cancer is a continuous pain caused by metastasis of lesions, and the pain is gradually aggravated, or radiating pain caused by cancer stimulation, while ordinary shoulder pain is intermittent and distending. 4. Accompanying symptoms: Shoulder pain caused by cancer, such as lung cancer, will be accompanied by cough, hemoptysis, chest pain, shoulder pain, etc. Shoulder pain caused by breast cancer will also be accompanied by painless lumps in the breast area, nipple overflow and other symptoms. In contrast, ordinary shoulder pain is usually only pain, soreness and numbness. 5. Relief methods: Shoulder pain caused by cancer is more intense and needs to be relieved by painkillers, while ordinary shoulder pain can be relieved by proper rest, massage, hot compresses and physical therapy. As we can see, there are many differences between cancer shoulder pain and common shoulder pain, and patients need to seek medical consultation for differential diagnosis through ultrasound examination and pathological examination for early detection and early treatment. Shoulder pain caused by cancer needs to be treated for the cancer, and the pain will generally be relieved after the tumor is relieved.