Well, tough question. Sounds like a lumpectomy isn't possible? As that would be the #1 choice. Mastectomy is major surgery, but actually not THAT painful or difficult, if she's in good health otherwise. On the other hand, DCIS isn't guaranteed to turn into invasive cancer... and there's the question: do you/she want to take the chance that radiation alone will take care of it? Mastectomy will reduce her risk of a further cancer in that breast for sure; lumpectomy/radiation would reduce the risk, though not as much; doing nothing would reduce the risk even less. But what IS the risk? Please ask her doctor for some statistics about recurrence, so you can help her make this decision. Good luck - PJHd