Arm pain after radical surgery for breast cancer is mainly caused by the following aspects: First, due to the contracture of scar caused by the gradual formation of incision scar, it is possible to have scar pulling pain when lifting the upper limbs or activities after the surgery, which is the most common situation. In the second case, when radical surgery for breast cancer is performed, the axillary artery and the nerves in the axillary sheath may be damaged, resulting in neuropathic pain, which is a kind of complication of breast cancer surgery in clinical practice. The third situation, caused by a combination of factors, may also be due to metastasis or recurrence in the postoperative period or in the short term, and the metastatic foci in the localized upper limb or axilla are more likely to cause cancer pain, which is also more common. Therefore, if you have arm pain after breast cancer surgery, it is better to go to regular hospitals to find the exact cause of the disease, and carry out systematic and standardized treatment according to the cause of the disease.