Radiation after clear MRI

amyelizabeth94

Hey all, 

My sister just finished neoadjuvant chemotherapy (TAC, I think) and got a clear MRI.  (The lump in her breast was physically gone after her 2-3 treatments).  She is scheduled for a BMX in May.  2 of her doctors have not recommended radiation, but the radiologist has.  She isn't sure what to do.  I've looked into this a bit, but can't seem to find much information.  

She is 33, BRCA1+, triple negative, Stage IIB with 1 positive node before surgery (estimated).  If surgery indicates NED, how much would radiation reduce the recurrence risk?  How does that number change if they find microcells in her breast tissue or nodes?    

Can she have a sentinel node biopsy and have them take more nodes if the sentinel node (s) do come back positive?    

Thanks for the help!