TNBC along with a brain tumor??

hello ladies. Maybe you all have some input. My cousin's wife recently got diagnosed with TNBC, and then found out she also had a brain tumor. They did her exams, and they told her that brain cancer was a separate cancer and not metastasis. They put her on chemo already to attach the breast cancer as it is growing at a very fast rate. As anybody heard of such a thing? a separate cancer? i am just so concerned and try to research as much as possible!!

thank u so much ladies