A biopsy is a short procedure during which a doctor takes a small sample of cells from the suspicious tissue. A pathologist examines the tissue sample under a microscope and determines whether the cells are normal or cancerous.
Your doctor may perform a biopsy to confirm diagnosis of a brain tumor. A biopsy also provides information to help guide treatment decisions.
We use the least invasive biopsy procedure possible, minimizing discomfort while still obtaining enough cells to make a diagnosis. We specialize in image-guided biopsy, which uses one of our imaging technologies to precisely locate the area where we need to take the tissue sample.
Doctors may use a type of biopsy called a stereotactic needle biopsy for tumors in hard-to-reach areas. They also use these tests in very sensitive areas within the brain that could be damaged by a more extensive procedure. During a stereotactic needle biopsy, a CT or MRI guides the surgeon to help avoid healthy tissue and other areas of the brain.
In some situations, a surgeon may remove part of a tumor for testing, or all of it. The goal is to determine whether the tumor is benign (noncancerous) or malignant (cancerous).
Spinal tap to diagnose brain tumors
Your doctor may also use a spinal tap to diagnose a brain tumor, with a small needle used to remove fluid from around the spine.
Doctors study the sample under a microscope to look for certain tumor cells that show up in spinal fluid. A spinal tap also helps doctors determine if you have a different condition that is producing symptoms similar to those of a brain tumor.
Pathology: Analyzing biopsies
After you have a biopsy, your nurse sends your tissue samples to our pathologists for review. A pathologist is a medical doctor who specializes in reviewing and evaluating lab tests, cells, and tissues to diagnose disease. Our pathologists analyze biopsy samples to determine whether the tissue is cancerous and, if so, what type of cancer it is.
At the Stanford Brain Tumor Program, all of our pathologists specialize in brain tumor diagnosis.
Because brain tumors are a complex group of diseases, it’s important to have expert pathologists on your care team. Years of experience studying brain tumors every day means your pathologist can accurately identify critical details. This information includes whether the tumor is:
- Cancerous or non-cancerous
- Invasive or noninvasive
- Shows a high or low cell grade (rating that describes how different the cancer cells are from normal cells)
- Is aggressive or slow growing
- Contains molecules that indicate the cancer subtype
All these details help form an accurate diagnosis, which is vital to your treatment plan. Your care team takes the time to do a thorough evaluation from the start, so that your treatment will be more effective.
How are brain tumors graded?
Doctors categorize cancerous brain tumors into 4 grades but do not use stages, unlike for other cancers. Factors that determine the grade include how fast the tumor is growing and its likelihood of spreading. The grade helps your doctor determine the safest and most effective options for treatment.
Tumor tissue bank
Our doctors and researchers work to thoroughly understand the true diversity of tumors and identify the genetic abnormalities that can play a role in brain tumor formation. That’s why it’s critical that our doctors have access to tissue samples to plan for each patient’s care.
At Stanford, we store tissue samples so we can use them for research, using the following process:
- After we take a biopsy (tiny sample of tissue), we ask you if you would like to give it to the tissue bank.
- The tissue first goes to the laboratory, where the pathologist samples it.
- If you approve, the tissue then goes to brain tumor research specialists. These doctors work with our clinicians (doctors involved in patient care) to identify new pathways of tumor formation and possible treatments.
- The data is made anonymous and is not available to you after donation, because we use it for research and not for clinical use in making treatment decisions.
Our tumor bank provides our doctors and other researchers with a variety of different types of brain tumor cells to study. As we work on new methods and tools for diagnosing and treating brain tumors, our goal is to move these findings from the lab into patient care.
Stanford Health Library
For confidential help with your health care questions, contact the Stanford Health Library. Professional medical librarians and trained volunteers can help you access journals, books, e-books, databases, and videos to learn more about medical conditions, treatment options, and related issues.