Vaccines offer three types of tools when it comes to cancer. Some, like the vaccines for hepatitis B and human papillomavirus (HPV), prevent cancer. Others, known as therapeutic vaccines, treat cancer. Most vaccines, however, fall into the third category of tools, routinely recommended vaccines. Less direct in their effects on cancer, these vaccines may be easier for affected patients and their oncology teams to overlook, yet they offer an insurance without which the path to recovery becomes distinctly more complex.