Almost everything about glioblastoma can be reconsidered later: the chemotherapy, the radiotherapy, the trials, the second opinions. The operating room is the exception. What is not requested before the operation cannot be recovered afterwards, and it closes doors that were open, including some of the most promising experimental therapies.
Dendritic-cell vaccines and autologous tumour-lysate vaccines are manufactured from the patient's own tumour. They need living tumour tissue, frozen fresh in the operating theatre itself, at the moment of resection. Several cell therapies work the same way.
By default, the tissue removed goes to the pathology lab, is fixed in formalin and embedded in paraffin. That is correct: diagnosis comes first. But formalin degrades the tumour's DNA and RNA, and paraffin tissue cannot be used to manufacture a vaccine. If nobody asked for a fresh frozen fraction to be set aside, months later there is nothing to work with, whatever the family is willing to pay or travel.
None of this replaces your medical team's judgement. They are questions you have every right to ask, and answers worth having in writing.
Print it and take it to the appointment before surgery. There is space to write down each answer, and to note who gave it.