Her 2 FISH test neg & pos?

Dear Summer77,

Thank you for getting in touch with us and welcome to our online community.  I hope you find it supportive and helpful.  My name is Adrienne and I’m one of the Cancer Information Nurses at Macmillan.

Pathology results like yours can seem confusing so it’s completely understandable that you would want to know how the cancer will respond to treatment.

A large number of breast cancers are considered HER2 negative despite having a small percentage of the cells (in your case 5%) come back as positive for the HER2 protein. 

Both HER2 positive and negative breast cancers usually respond to chemotherapy.  Immunotherapies such as pembrolizumab and trastuzumab (Herceptin) are also very effective in helping to prevent recurrence.  Both of these drugs lock on to different parts of the HER2 proteins which blocks the receptors and stops the cancer cells dividing and growing. 

Pembrolizumab is usually given for a breast cancer which is hormone negative and HER2 negative (also called triple negative) whereas trastuzumab is given for HER2 positive cancer. 

It sounds as though your oncologist is initially treating your cancer as triple negative but with the added option of Herceptin later, so as to cover all grounds and ensure best possible outcome.

I really hope this was helpful but please know that you can call one of our nurses to talk this through further.

Take care and best wishes with your treatment,

Adrienne

(Cancer Information Nurse Specialist)

You can also speak with the Macmillan Support Line team of experts. Phone free on 0808 808 0000 (7 days a week, 8am-8pm) or send us an email. 

Ref: AM/AR

Thanks so much for replying. That makes sense and puts my mind at ease. Thank you.