  We calculate all the four-photon helicity amplitudes at the one-loop level in
a massive theory using multiple-cut methods. The amplitudes are derived in
scalar QED, QED and $\textrm{QED}^{\caln =1}$ theories. We will see the origin
of rational terms. We extend the calculation to the simplest six-photon
helicity amplitude where all photons have the same helicity.
