Hey MJRScully
Sorry about your diagnosis and subsequent surgery. It sucks losing a boob and having to deal with this stuff.
I had a left mastectomy in August for DCIS and early breast cancer. Turned out I had 84mm of DCIS with positive margins posterially....so no clear margins from the chest wall. They suggested I consider radiation therapy. After talking with the radiation oncologist, I decided to go ahead with the radiation. She did say there wasn't super clear data for the benefits of doing it / risks of not doing it. She made a best guess of something around 10% recurrence without rads, and 0.5% with (although my hubby thought she said 0.05%....we can't agree! I will ask her when I see her again). She also told me that if my DCIS returned it had a 50% chance of being invasive.
I was initially reluctant and was trying to avoid radiation. However after meeting with her and discussing with hubby, I decided to go ahead with it. I figured anything that reduced that chance of that b*#%tard coming back was a good thing. There's not much left on my chest wall to remove if it returns. I live regionally, and it takes an hour one way to travel over for the rads. I only started last Wednesday and will be having it for three weeks. Because it's my left side, I'm doing the Deep Inhalation Breath Hold. They've also given me a tube of StrataXRT, a gel to apply to the area which is apparently really good to prevent a bad skin reaction.
It's a hard decision, especially when the data isn't clear. What helped me decide was simply that I wanted to do everything I possibly could to reduce the chance of it coming back. I know it's not a 100% guarantee, but if it reduces the risk I decided it was worth it. I'm also on Tamoxifen (as the little invasive cancer was hormone positive) but taking a break while I have radiation; again I was reluctant but I'm going with the same theory - every little bit reduces the chance of return by a few percent.
All the best with your decision, it's not easy. Take your time to consider, discuss and do your research. Ask lots of questions. Take care x