How long before radiotherapy helps with bone pain? I've been fighting my insurance company to cover radiation for a large and very painful lytic lesion on my sternum, and perhaps naively assuming that the pain would start to lessen right away. But I had the first of five 3DCRT sessions yesterday, and the pain is significantly worse now. For those of you who had radiation to help with pain, how long did it start to work? Days, weeks? Did particular pain meds help more than others? I'm not supposed to apply ice or heat. Thanks in advance for anything you can remember.