Microwave ovens allow a maximum leak amount of only 5mW, which is really small1.
If more radiation were let out, you would experience microwave burns2.
Microwave radiation is non-ionizing. Differently from x-rays and gamma rays, the microwave photons simply do not have enough energy to cause cancer through ionization3.
Given the previous well-known facts:
- If you are not burned, you are not being affected by microwaves because they don't leak out.
- If you were to get burned, you would still have no ionizing radiation impact.
Finally, research shows that microwave-length radiation does not cause cancer, but the studies relate mostly to different kinds of microwaves (for example the waves emitted by a cell phone)4.