Can hair transplant for bald spots cause cancer? What are the safest ways to treat bald spots on the head with your own hair without side effects/harm?

Absolutely no chance. There has never been a single report of any type of cancer (skin or otherwise) associated with or thought to be caused by hair transplants. Since transplants involve surgery, the same "side effects" occur as do with ANY type of surgery, ie, bleeding, pain, risk of infection and anticipated scarring....There is simply no way to avoid them. The degree of risk varies due to many factors. .
Never . Read that it could cause cancer and transplanting your own hair is the only way to fix it using yours naturally .