The possible causes of chest pain after menstruation are as follows: 1. Breast enlargement, which is benign in itself, but has the possibility of cancer, and needs to be observed regularly. It is cyclical, with pain appearing at the beginning of menstruation and relieving or disappearing at the end of menstruation. 2. Breast fibroids, which are benign lesions, but can deteriorate. It is often a solitary lump, occasionally visible as breast swelling and pain, and is not related to the menstrual cycle. The disease will suddenly increase in size during pregnancy and lactation, causing great distress to the patient. 3. Breast cancer, advanced breast cancer invades the nerves causing breast swelling and pain, which will be accompanied by unevenness and folds of the breast, or swollen, painful nipples and bloody overflow, etc. Chemotherapy combined with targeted therapy can be given to prolong the life of cancer patients.