Breast pain in women is a particularly common symptom in the breast. Breast pain is due to the compression and pulling of the nerves that travel through the interstitium of the breast gland. The effects of estrogen and progesterone on the interstitium of the breast trigger congestion, edema, and structural changes in the interstitium, all of which harden the interstitium, so that the nerves that travel through the interstitium of the gland are compressed and cause pain. Breast pain is a visceral pain and therefore cannot be precisely localized. The nature of the pain is usually localized as stabbing, vague, or radiating pain, and radiation to the armpit is also a very common manifestation. For middle-aged and elderly women, if the pain in the left chest is more pronounced, the first step is to identify whether the pain is from organic lesions of the heart or lungs. If heart and lung problems are excluded, it is definitely breast pain.