There are no cancers totally preventable by vaccinations.
Cancers are due to cell mutations and subsequent proliferation of these mutated cells. There can be multiple triggers for such cell mutations, including certain viruses.
Hence, to be more accurate, I would explain that some vaccines CAN reduce the risk of cancers but not totally prevent it.
A good example is the Cervical Cancer Vaccine or HPV (Human Papillomavirus Vaccine). It reduces the risk of contracting cancer-causing strains of HPV which is a direct causative factor for cervical cancer, ie HPV causes cell mutations in the cervix, leading to cancer. However, there are many HPV
strains and the current vaccines only protect up to 9 strains of the virus which make up the majority of cancer-causing strains. However, it does not totally eliminate the risks of contracting the other rarer strains of HPV which cause cancer as well.
Another example I always recommend is the Hepatitis B vaccine which prevents someone from contracting the Hepatitis B virus. Being a Hepatitis B carrier is a major risk factor for Liver Cancer. Hence, if one is protected against this virus, it greatly reduces the chance of becoming a carrier of the virus. However, other than Hepatitis B, there are other risk factors for Liver Cancer as well. As such, the vaccine can only reduce the risk but not totally prevent Liver Cancer.