Vaccines are showing promise as medication therapy for patients with advanced-stage lung cancer. A new vaccine, however, recently failed to extend the lives of certain cancer patients.

While widely researched, highly sought after and well-funded, vaccines for most cancers aren't easy to implement. Since a vaccine trains the immune system to attack foreign cells, and cancer cells are still human, the level of precision is difficult.

Medicare has announced it will pay for Provenge ( sipuleucel-T ) to treat metastatic prostate cancer. This drug extends the life of patients by about four months.