Would you recommend adjuvant breast radiation following lumpectomy for a well-differentiated adenoid cystic carcinoma that appears to be a breast primary?  

For an adenoid cystic carcinoma of the breast treated with breast conserving surgery, I would recommend adjuvant radiotherapy after BCS. Though data are limited, there are both a SEER analysis and RARE cancer network study that demonstrate an advantage to radiotherapy following conserving surgery. I...

There are limited data. Based on head and neck data, I have treated a few patients, one being very recently, for which I delivered 60 Gy equivalent to the surgical bed.

If there are small low grade negative nodes and wide free margin, one can treat limited breast to lumpectomy site versus observations.