what to do when doctors disagree

BVGS

 I was diagnosed with invasive ductile carcinoma in Dec. After additional testing it was determined to be a large, agressive tumor with a high oncotype score but no lymph node involvement. At the advice of my oncologist I agreed to chemo first. Had 4 cycles of A/C. Repeat mammagram showed the tumor had shrunk. Had lumpectomy in mid-May. The surgeon told me the path report showed clean margins.

When I went to see the radiation oncologist, who is at a different hospital, he told me that he routinely has all path from outside reviewed. His path dept says they found DCIS. & said without added surgery my risk of recurrance would go up 30%.
  Went back to the surgeon. He said he would do an additional surgery if it 'would give me peace of mind' but made it obvious he didn't really think it was necessary.   

  I know that different doctors might have different opinions about the best treatment, but I really thought that whether there are adequate clear margins was a fact not an opinion. So now I am between the proverbial rock and a hard place.  Thinking about a 3rd path report. Obviously I don't "want" more surgery, but I even more don't want to increase my risk of recurrance. When the doctors disagree, how does a patient decide???