Biopsy-only (unresectable tumor)

What it is

A biopsy-only approach obtains a sample of tumor tissue for diagnosis without attempting to remove the tumor. It is used when a glioma cannot be safely resected — for example, because of its location in a critical area or its widespread or deep involvement — and treatment then relies on non-surgical therapies.

Understanding Biopsy-only (unresectable tumor)

Not every glioma can be removed. Some are located in areas where surgery would cause unacceptable harm (such as deep midline structures or the brainstem), some are too widespread, and some involve critical functions throughout. In these situations, a biopsy (often stereotactic) provides the tissue needed for the integrated diagnosis — including the molecular features that guide treatment — without the risks of an attempted removal. Once the diagnosis is established, treatment proceeds with the appropriate non-surgical therapies: radiation, chemotherapy, targeted therapy, or clinical trials, depending on the tumor type. For example, a diffuse midline glioma in the brainstem is typically diagnosed by biopsy (or sometimes imaging) and treated with radiation, as it cannot be removed. The biopsy-only approach ensures accurate diagnosis when surgery is not an option. Understanding the biopsy-only approach clarifies how unresectable gliomas are diagnosed and treated.

Why it matters

Understanding the biopsy-only approach helps patients and families see how a glioma that cannot be safely removed is still accurately diagnosed — through a biopsy — so that the right non-surgical treatment can be chosen.