43, single masect & chemo(completed) my surgery discovered lymph/muscle positive idc- dr wants to do radical masectomy aren't these rare? i'm scared!

Not rare: There are many choices for treatment of breast cancer. It all depends on many things like age, type of cancer and general health. In your case I would suggest that you obtain a second opinion from an oncologist who deals with breast cancers. The expert opinion will ease you fears. Remember that a famous movie star Angelia recently had a radical mastectomy. If necessary it can be life saving.

They are rare: more recently, mainly because invasion of muscle is a rare occurrence because of earlier stage at which breast cancers are diagnosed. If you are unsure about your surgeon's recommendation, you should get a second opinion.