My daughter was in a similar situation with the same type of tumour aged 21 at the time. Check if they have tested for the biomarker BRAF V600E (https://en.wikipedia.org/wiki/Cancer_biomarker). Apparently PXA tumours often have this and if so there are drugs that might help. My daughter was put on Dabrafenib (another drug, like Nivolumab, originally developed for Melanoma) which worked very well, giving her several years good quality life without serious side effects. We have some difficultines now but she is nearing 5 years from when it was originally found. Irrespective do keep advising what drug treatment they propose or have discounted in case I or anyone on this forum has heard of other possibilities. All the best with it anyway. David.