For a breast cancer patient who previously underwent lumpectomy/SLN biopsy and PBI with brachytherapy, what volume would you treat for an isolated axillary recurrence s/p ALND and chemo?

How long has it been since initial brachytherapy?

If > 2 years from initial treatment, I typically will treat breast/chest wall and regional nodes.

If < 2 years, I would consider regional nodes only; however, would also look at the original plan as some UOQ PBI cases may give a dose to the axilla.

This most likely reflects a false negative SNLN which is uncommon but can present with a delayed axillary recurrence. I would get a breast MRI as part of the workup to rule out concurrent IBTR or new primary in the breast. If it is negative, I would recommend ALND followed by RT to the undissected a...