Do you recommend inguinal hernia repair before or after chemoRT for inguinal node positive anal cancer?

I would strongly recommend doing this after chemoradiation. The reason is that the dermal lymphatic drainage will be altered after surgery and any in-transit cancer cells will attempt to go to the contralateral inguinal nodes. I have seen dermal lymphatic recurrences five times in my career after inguinal surgery and subsequent chemoradiation. They have occurred in the scrotum or vulvar skin possibly because these areas are spared with IMRT and they are very difficult if not impossible to salvage. Subsequent recurrence location is hard to predict.