Standard of care for recurrent or secondary malignancies in a previously irradiated field is surgery. For inoperable patients or residual tumor after surgery, standard of care would be palliative chemotherapy. For a small subset of patients (good performance status, small radiation fields) re-irradiation can be performed. In this study the established concept of re-irradiation with photons will be transferred to proton radiotherapy. Proton therapy has the advantage of a steeper dose gradient to normal tissues, thus-theoretical advantages for lower toxicity.