What dose and fractionation is safe to use for palliation of a large pelvic mass several years after definitive prostate brachytherapy?  

The prescription, technique and modality would depend on histology, size and involvement/distance from organs at risk. At our institution we have often utilized high-dose spatially fractionated radiation therapy (GRID) for large tumors followed by a traditional hypofractionated palliative RT regimen...