For patients receiving concurrent chemoradiation for anal cancer, what is your ANC threshold for holding radiation or switching to a boost plan to limit myelotoxicity?  

I hold chemoRT for an ANC< 1.0.  If the ANC does not increase in a two or three days then 1-2 days of g-csf will help.  One thing to remeber - do not give g-csf the day the patient is receiving chemoRT.