I don't think cancer qualifies as "a life" at all sorry. Taking anti-biotics to kill a bacterial infection might be a better comparison.

Cancers don't become cooing babies if left alone to grow.

Even if you are pro-choice, comparing an unborn child to a disease that kills millions is a poor move.

Later on, it's also just cells. That kind of naive reductionism leads us to reducing a human being to cancer.