In an early stage breast cancer post neoadjuvant chemotherapy, do you repeat ER/PR and HER2 status on the surgical specimen if there is residual disease?

It can be more nuanced than always repeating all the receptors. If there is residual disease after NAC, and the cancer is grade 3, I do feel it is worthwhile to at least repeat HER2. After all, we have good options for reducing the risk of recurrent HER2+ disease in the residual disease after NAC setting (e.g. T-DM1).

I will sometimes repeat all 3 receptors on residual disease, most often when there is a change in the grade or something was a little off in the initial setting - e.g. a recent tri...

Repeat markers after neoadjuvant therapy can be helpful clinically. Certainly if initially, ER and/or HER2 are negative, will repeat on residual disease. Looking for a target if we don’t have one, rather than disqualifying an initial target.

As a general principle, a biopsy is often just a small representation of a tumor, especially larger ones, and it makes clinical sense to retest what’s left.

Having said that, biomarker results between core and post neoadjuvant residual tumors are usually in...

Yes, repeat.

I will repeat markers, it may change treatment.

Keeping the same theme—a woman in her 50s with stage IIB (T2N1G3) invasive ductal carcinoma initially ER/PR-positive and HER2 2+ with FISH-negative results, treated with neoadjuvant dose-dense AC followed by paclitaxel, who subsequently underwent mastectomy with good response but had residual macrometastatic nodal disease and conversion to HER2-positive status on the surgical specimen (HER2 2+, FISH ratio 2.4, average signal 6.6), and who is about to start adjuvant radiation, should adjuvant the...