Dear castjs: The general rule of thumb in surgical management of a single spot of breast cancer is lumpectomy with clear margins followed by radiation therapy or mastectomy. Sometimes additional surgery is needed to yield a clear margin and a lumpectomy is still possible with a good cosmetic result. Sometimes, removing too much tissue in a lumpectomy could result in a deformed breast. There may be additional reasons why your surgeon is recommending mastectomy. You should have a discussion with him/her regarding the reasoning. If you are not satisfied with the responses, you may wish to get a second surgical opinion.
I had stage one Breast Cancer, and I decided to have a Mastectomy. I wanted no treatments. I felt safer having that done This was two years ago, and I have never been sorry. The operation isn't bad. I hardly had any after pain. Your Surgeon gave you good advice.
Blessings to you.
Annie