Pain in the paratesticular breast is not necessarily a sign of cancer, but may be caused by changes in hormone level, excessive secretion of breast milk, breast hyperplasia and other reasons. 1. Changes in hormone level: During menstruation and pregnancy, the level of sex hormone in the body will change, which may cause stimulation to the breast tissue and lead to pain in the paratesticular breasts, which is a normal physiological phenomenon. 2. Excessive secretion of milk: If women are breastfeeding, if they have excessive secretion of milk, the milk in the paratesticular breast cannot be discharged from the body, which will cause stagnation and thus induce pain. 3. Mammary gland hyperplasia: Usually too much mental stress, depression or staying up all night and other bad habits can lead to mammary gland hyperplasia, localized hard knots, lumps, and also lead to pain in the paratesticular breasts. In addition, a small number of breast cancer patients may appear paratesticular breast pain, once the pain and discomfort should be promptly seek medical attention to clarify the cause of the disease, targeted treatment.