Usually what is meant by 'cancer vaccine' isn't the HPV or Hep.B vaccine where the target is the viral causative agent of cancer. They are typically therapeutic

Usually what is meant by 'cancer vaccine' isn't the HPV or Hep.B vaccine where the target is the viral causative agent of cancer. They are typically therapeutic rather than prophylactic, inducing immunity against cancer-specific antigens to overcome the immune evasion mechanisms cancer cells use, tog get the relevant elements of the immune system to attack cancer cells directly. Several are already approved, but no one inn the know is saying that a cure-all cancer vaccine is around the corner, cancers are very diverse and the vaccine approach may only be applicable in very niche cases where cancer antigens are sufficiently different enough from normal proteins expressed by healthy cells — and just like targets of immunotherapy and chemotherapy, there's no promising that cancers won't evolve to overcome therapeutics.