Hi @AmandaTR, totally agree with @Afraser. You are entitled to have answers to your questions and a good oncologist will explain their recommendation to you for a treatment.
While I had a medical background, I don't have the knowledge of an oncologist but I trusted mine and got on well with them. I had radium because I didn't have a mastectomy so it was important to reduce any chance of a stray cell remaining in my breast.
I will say that a small slow growing cancer is not a reason to not have radium as even slow growing cancers can shoot out cells. Radium reduces that risk of reoccurance. It was my choice was to keep my breast and my surgeon and oncologist agreed they could treat me to reduce my reoccurance chances and recover fully.
Have a chat to your gp or breast care nurse. If you don't like your oncologist ask your gp to refer to to one for another opinion.
Radium is very accurate these days so very little risk to other areas outside the breast tissue. Not sure where you get the idea the heart and ribs could be damaged. The internet is a dangerous place and it can lead us down rabbit holes.
I hope you get the answers you need so you can be comfortable with your treatment decisions and have no regrets later on. Best wishes
