Canceling 5th birthday party for extremely bad behavior?

My daughter will be 5 in 1 week. Her behavior is out of control. Everyday is a struggle. She throws a fit 3 times a day, she refuses to listen to anyone, she acts up in daycare (she aggravates a little boy, she hits, and she screams) she is down right defiant. My husband and I have tried everything and were exhausted. She hits me, screams at me, tells me no, and spits at me. I don't know what to do anymore. Is canceling her party too extreme? I would still celebrate her birthday, but not have her party.