Deciding what treatment

10 years ago I was diagnosed with Stage 1 breast cancer in my left breast. The treatment was lumpectomy with chemo, radiation and 5 years of tomixiphen.  now I have been diagnosed with DCIS in my right breast, plus atypical ducts, highly suspicious for invasive ductal carcinoma in my left breast.  The doctor is leaning to have a surgical biopsy on the area of the left breast to find out exactly if it is breast cancer.  Then if it's not cancer do a lumpectomy on the right breast with radiation.  If it's cancer then I would have a bilateral Mastectomy.  I'm wondering if I should just do the mastectomy now and not have to worry about cancer in my breast tissue in another 10 years.