For a small focally positive DCIS margin in the setting of invasive disease and negative invasive margins, not undergoing re-excision, what boost dose would you use?

Yes. I would give a higher boost dose in the setting of a positive margin. In the old days, at 2 Gy per fraction, I would tx positive margins to a total of 66 Gy, and this usually worked out well. Occasionally, the patient would get some telangiectasias long-term. With Canadian hypofraction, I have ...