When scientists inject other animals (such as humans, mice, and cattle) with oncogenes, they tend to develop highly aggressive forms of cancer. You know who doesn't? You guessed it: the naked mole rat. Even five years later, the mole rats were cancer-free. According to The Scientist, "naked mole-rat tissues are better able to recognize abnormal cells, neutralize their tumorigenic properties, and repair their DNA. Should that fail, the cells are ushered into programmed cell death pathways."
(Check out this article for more interesting observations regarding naked mole rats and cancer, and this one for more info about their genome analysis! Oh, and this piece talks about the chemical that researchers have discovered to be a crucial link between the naked mole rat and cancer avoidance.)