Is it appropriate to use hypofractionation to treat breast cancer when the patient is receiving concurrent TDM-1 (Kadcyla)?  

We have been using it routinely with no increased acute side effects and are looking at our data systemically.

The use of Kadcyla does not influence my decision on fractionation. There are reports of increased severe skin toxicity and I've seen that in a case myself with regular fractionation. Anecdotally, I feel that hypofx actually has less skin toxicity with Kadcyla, consistent with the hypofx trials show...