From a fast search in Google, life expectancy in bats is 5-15 years. A long life of 70-80 years gives more time to accumulate mutations and get a cancer.
Also, probably only bats in zoos get a cancer diagnosis. Most ills bats just die in the wild and are eaten by other animals.
Also, probably only bats in zoos get a cancer diagnosis. Most ills bats just die in the wild and are eaten by other animals.