Marma
Good to hear that your father in law is back on the 
Erbitux.  While dropping Cisplatin treatments may be no big deal ( I never took it, but David did and his post speaks for itself)- that's not what I was told about 
Erbitux as a single agent  My RO was insistent that even with the thrush, mucositis, etc in my mouth, my best chance for a cure was to have all 8 of my 
Erbitux treatments done each week.  He was open to postponing the last one for one week -based on the half life build up but I was able to do all 8 non stop.  More than a year ago, he stressed everything in Gary's post about the synergistic effect.  Interestingly enough, although he was finishing up a clinical trial on 
Erbitux and Csyplatin combos, he recommended that I try 
Erbitux alone to avoid the Csyplatin long term effects on hearing etc. that he saw in his patients.