@jlwilcox I'm not qualified to answer if it will harm your heart--have you asked the doctor directly? Someone else on this chat might have personal experience, too, but not me. I believe that in some cases if the position of the lump warrants it there are breath holding techniques that can help. But again, this is outside my experience. I hope you can get a clear answer. I think the reason folks talk about skin issues is that is a common, and treatable, side effect. When is your radiation treatment starting?