There is no evidence that Restylane is not safe in someone who has had breast cancer. There is no immune disorder seen-to-date as a result of Restylane or Juvederm injections. In fact, continual treatment of ones appearance during the post treatment phase can help a cancer patient feel better about themselves. By doing something for oneself, the person is validating their optimistic attitude about their future existence which can help the immune system continue to fend off the cancer. Positive attitude helps this innate defense mechanism whereas stress and negativism probably interferes with the immune system's full abilitiy to fight the growth of the cancer.