Hello Lisalilly, 

It does sound like your mum has been diagnosed with a very rare cancer and there is some information on mucinous tumours on our rare types of breast cancer page. You can also find out more about mucinous breast cancer in the Breast Cancer Now website on this page.  It's a very difficult decision to have to make and I hope that you can talk to your mum's consultant about this and see whether they would recommend the chemotherapy treatment. I thought I would also mention that I found a thread from last year where another member [@gelatosun]‍ mentioned being diagnosed with triple positive mucinous breast cancer. It may not be exactly the same situation as your mum but you can find the thread here and don't hesitate to respond to it if you wish.

Hopefully others who have had a similar experience and diagnosis will be along shortly to share their story with you. As I mentioned on your other thread too, our nurse helpline is only a free phone call away and open Monday to Friday from 9am to 5pm so don't hesitate to ring them on 0808 800 4040 if there is anything you ever want to ask them. 

Best wishes to you and your mum, 

Lucie, Cancer Chat Moderator