Humans are by animal standards very long lived and naturally quite resistant to developing cancer. We have many more anti-cancer biochemical and genetic systems (antioncogenes) that work much better than the same systems in mice.
1. Which mouse? An inbred laboratory possibly immunodeficient strain, a genetically engineered mouse to GET cancer at a high rate, or maybe a wild type free-range mouse?
2. Which cancer? Do you realize that it is almost impossible to get realistic models of prostate cancer or that mice simply live to short to get colorectal cancer - even when the relevant mutations are introduced?
Yes mouse cancer in not a great model for human cancer and we probably should not be using mice - about the only good thing they have going for them as a model is they are small and cheap.
Personally I would like to see us using pets (dogs and cats) much more as their cancers are a much better match to human cancers in both how they develop and how they progress. That we are not taking better advantage of this resource to develop new treatments is a tragedy.