For those of us whose immune system didn't work as designed and we get the cancer diagnosis there are always treatment options, Lumpectomy is one option and mastectomy is another. IT IS SURGICALLY IMPOSSIBLE to remove all (100%) of breast tissue. So even if you get a mastectomy there are still breast cells left behind BUT these breast cells are NOT where a recurrence comes from. The recurrence is from mutated cells made by the stem cells and the immune system failure to recognize these abnormal cells and destroy them.
If you don't want a recurrence find ways to improve your immune response to these abnormal cells. This is usually achieved through diet, lack of ingestion of toxins (in our food, air, water, clothing, furniture, other environmental factors) Can't elimtinate all of them but you can cut back your exposure.
Try thinking about your surgery this way: You have a bad kidney that needs to be remove. You don't want to have to deal with kidney disease in the future. Would you remove your second kidney on the assumption that it MIGHT come back? Logical answer is no. But then again being told you have a bad kidney doesn't feel the same as being told you have cancer.
Give this some thought before you leap into action, Ask the surgeon if you have mastectomy will that mean you can't get a recurrence. If the surgeon say absolutely you won't get a recurrence with a mastectomy = run the other way because that isn't truthful and these are no scientific studies to back that up. Ask surgeon was is the decrease in the percentage of possible recurrence with lumpectomy and with mastectomy. It all depends on where the tumor is, what kind of tumor it is, how far along are the cells that make up the tumor (meaning do they still resemble regular cells or still able to function as somewhat normal cells or have they all gone the all the way to doing only cancer functions - reproducing over and over and doing nothing else.
Ask an oncologist what is the possibility of a recurrence with or without chemo, radiation, or surgery and what kind of surgery. Get the medical opinion on surgery and not just the surgical opinion.
Ask tons of questions of all those on your treatment team. Seek info from where you get treatment and from research or teaching hospitals or clinics. Stay away from Dr. Google as much misinformation lurks on his pages.
Hope that helps