Do you hold endocrine therapy during adjuvant breast radiotherapy?   

No, we don’t hold endocrine during RT as data suggests no difference in toxicity or local control. The only exception is CD4/6 inhibitor which is now standard for high-risk node positive patients where we start the medication after RT.

I start endocrine therapy after RT. For one, I don’t think there is a rush to get endocrine therapy going and would rather focus on the patient being able to tolerate it for the long term. And two, if radiation works best on quickly dividing cells, I don’t want to stunt their proliferati...

There is no data that shows a detriment to holding endocrine therapy in all the NSABP studies. Theoretically, you would reduce cycling. Recurrences are so few that it would be hard to prove a detriment. I remember reading a mouse article that suggested a higher risk of pneumonitis with concurrent ta...

If an aromatase inhibitor, I start concomitant with radiation, no reason to wait. Tamoxifen elicits more negative reactions from our radiation oncology colleagues, so I typically wait after, especially if it’s a short course of radiation.  Remember that in many patients with ER-positive ...

Standard of care with adjuvant breast therapy has been adjuvant chemotherapy followed by adjuvant radiation and hormonal therapy. Radiotherapy concurrent with endocrine therapy didn't increase or decrease either the incidence of radiation-induced toxicity or the survival rate compared with that of t...

Yes, it is important to avoid concurrent toxicity and watch the patient closely; if there are adverse effects, hold till radiation is completed.  I was concerned about the cytostatic effects, shown in concurrent chemotherapy + adj endocrine Rx trials, so still some concerns there.