Hi vaee,
I sorry I didn't see this sooner...I wish others would have responded, too.
NO...breast pain is NOT necessarily a sign of breast cancer... what CAN cause pain in breasts can be things like cysts, calcium deposits, muscle strain (yes, it can affect the breasts)...and sometimes they just seem to develope pain which comes and goes. There is a form of mastaitis that can also cause breast pain. I would Google "causes of non-cancerous breast pain" ...for a more complete list..

The sneaky thing about breast cancer is that it may have no warning signs such as pain. If you are at all worried, however, please do go in for a check up. Good luck to you!