I guess it depends on whether the photons have enough kinetic energy to knock a nucleotide out of a DNA molecule.
If they don't, you're safe, if they do, you would have to multiply the number of times a nucleotide gets knocked out, with the chance of developing cancer from that event (pretty small chance actually, it might even be that a base pair needs to be knocked out to create a mutation, not just one nucleotide, I wonder if anyone did any research on that).
Other than that the only thing that could happen is excitement of your molecules, making your body temperature rise, but I would guess the power you absorb over the volume of your body would be insignificant compared to other influences.