Overnight left shoulder and neck pain is not necessarily cancer, but may be myofasciitis, muscle strain and cervical spondylosis, etc. Further examination is recommended. 1. Myofasciitis: clinically, left shoulder and neck pain can first be considered as myofasciitis of the shoulder and neck caused by prolonged work at desk or catching a cold due to low air conditioning temperature at night, which leads to pain on the next day due to aseptic inflammation. 2. Muscle strain: If the height of the pillow is not suitable at night or the posture is not proper for a long time, it may lead to muscle strain and other injuries of the neck and shoulder, and strain of the neck ligaments, resulting in pain. 3. Cervical spondylosis: If there is a herniated cervical disc, the herniated disc may compress the nerve root, resulting in pain and numbness in the left side of the neck, shoulder and neck. The performance of the left shoulder and safeguard pain overnight. 4. Of course, it cannot be ruled out that bronchopulmonary cancer occurs at the tip of the lungs, leading to compression of brachial plexus nerves, which results in discomfort in the shoulder and neck. Therefore, it is not necessarily cancer, but it cannot be completely ruled out as well, and further examination needs to be recommended to clarify the etiology.