Botox is a protein that blocks neurotransmitter signals to contract muscles, and it works only on the muscles where it is injected. There is no change in risk of breast cancer whether Botox is used or not, so if it makes you feel better about your appearance, just go right ahead!
None of the presently-used fillers have any effect on breast cancer risk either. Ask your doctor for information about your speific filler of choice if you have any concern at all.
To put things in perspective, there are many risk factors, not only for breast cancer, but for virtually every aspect of our health and well-being. Breast cancer risks are appropriately concerning, but you need not worry about Botox or fillers having any effect on you own individual breast cancer risk factors. Best wishes!