Why does cancer hurt?

The causes of cancer pain include: first, caused by the tumor itself, such as tumor invasion of nerves, nerve destruction; second, tumor complications, such as tumor can cause infection, bleeding, but also pain; third, pain caused during tumor treatment, such as surgery, endoscopy, and some interventional treatments, including radiotherapy and chemotherapy, can cause pain; therefore, tumor pain consists of these three parts. Pain caused by the tumor itself, the tumor can invade the pleura to cause chest pain, but also can invade the bones to cause bone pain. For example, liver metastasis of lung tumor causes liver pain, brain metastasis causes headache, and even coma, so the pain caused by the development of the tumor itself is also the main cause of pain.