Champion swimmer with rare brain cancer urges UK to do more to help people with condition
oligodendrogliomas, rare tumours that make up [about 3%](https://www.cancerresearchuk.org/about-cancer/brain-tumours/types/oligodendroglioma#:~:text=Oligodendrogliomas%20are%20rare.%20About%203%20out%20of%20every%20100%20primary%20brain%20tumours%20(3%25)%20diagnosed%20in%20England%20between%201995%20and%202017%20were%20oligodendrogliomas.) of all brain cancer