How can the body maintain homeostasis with basal cell carcinoma?

It doesn't: If you have a teacher who talks about "maintaining homeostasis" when there's a cancer, have a serious talk with that teacher's supervisor. Any cancer, untreated, will eventually kill the owner. There's no question of "the body's natural ability to heal" here. The immune system fights some skin cancers but this never cures without an assist from today's high-tech Rx's.