The way I see it it is another arrow in the quiver.
Radiation damages your DNA and the idea is that cancer cells with their faster metabolism and growth get damaged more and decide to die (apoptosis). Cisplatin damages (cross links) your DNA and also screws up DNA repair, but it does so systemically. If you apply both, cisplatin enhances the effect in the radiated region, but also has some long distance effect. Erbitux targets the grow factor receptor (EGFR), which is SOME cancers is overexpressed and susceptible to the Erbitux (antibody). So the mechanism is different from cisplatin but since you also weaken the susceptible cells in the radiation field I would also expect some synergism. What would be interesting is to have statistics/data on a concurrent regimen of radiation, Erbitux (if biomarker present) AND cis or carboplatin. Perhaps this could allow you to lower dosages or rads.....

M