There are some promising efforts for vaccines against cancer. It’s teaching your immune system to kill cells that were supposed to die on their own. It’s a relatively recent development, though.

Plus, as should always be stated with cancer treatments, there is no singular “cancer”. It’s a class of related problems that need to be handled individually. Vaccine against prostate cancer shouldn’t be expected to work against breast cancer. Anything that claims to cure cancer in a blanket way should be treated with great suspicion.