Would you use OncoType Dx to guide adjuvant therapy recommendations in the context of locally recurrent, node-negative, ER+ breast cancer previously treated with endocrine therapy alone?

Assuming that 1.) the recurrence is in ipsilateral breast tissue post-radiation therapy, 2.) the patient is on adjuvant hormone therapy, and 3.) the pathologist concurs that this is not a new primary, we could approach this problem on multiple fronts.

1.) Does the tumor harbor an ESR1 mutation? Altho...