Unknown. Some women have more sensitive breast than others and this may be due to hormones or breast composition.
Common problem. Fibrocystic disease/changes is very common in women. This is most often seen during the menstrual cycle. Breasts feel lumpy and painful which is caused by cyst formation (fluid filled areas) due to hormonal changes. Some women may have these changes without being on their menstrual cycle. Caffeine may cause the cysts to be overactive resulting in pain. This is not related to cancer.