A brain tumor is an abnormal growth of cells within the brain or surrounding structures. Tumors may be primary — originating in the brain itself — or metastatic, spreading from cancer elsewhere in the body. They range from slow-growing benign lesions to aggressive malignancies requiring prompt treatment.
Brain tumors can produce symptoms that overlap with other neurological conditions. New or worsening headaches should be evaluated to exclude a tumor, particularly when accompanied by neurological symptoms — conditions such as migraine headaches, brain aneurysm, and subdural hematoma can present similarly and require MRI to distinguish. Patients with a known systemic cancer diagnosis should be evaluated promptly for stroke or metastatic disease when new neurological symptoms develop.
Causes
Primary brain tumors
Primary brain tumors arise from brain cells, supporting glial cells, or the meninges (the membranes surrounding the brain). The most common types include gliomas (which include glioblastoma, astrocytoma, and oligodendroglioma), meningiomas, and pituitary tumors. The exact cause is not fully understood, but genetic mutations — sometimes inherited, sometimes occurring spontaneously — play a central role. Prior radiation exposure to the head is the most clearly established environmental risk factor.
Metastatic brain tumors
Metastatic tumors are actually the most common brain tumors in adults, outnumbering primary brain tumors. They originate from cancers elsewhere in the body — most commonly lung, breast, melanoma, kidney, and colon — that spread through the bloodstream to the brain. Patients with advanced systemic cancer are at significant risk of developing brain metastases, which frequently present as multiple enhancing lesions on MRI.
Symptoms
Symptoms depend on the tumor's size, location, and rate of growth. Common symptoms include persistent headaches (often worse in the morning or with Valsalva), seizures, cognitive changes or memory difficulties, personality or behavioral changes, weakness or numbness on one side of the body, vision or speech disturbances, and difficulty with balance and coordination. Symptoms from increased intracranial pressure — including nausea, vomiting, and altered consciousness — may occur as tumors enlarge. Focal neurological deficits localize the tumor to specific brain regions and are an important clinical clue.
Diagnosis
A detailed neurological examination assesses cognitive function, reflexes, coordination, and cranial nerve function. MRI with gadolinium contrast is the gold-standard imaging study, providing detailed visualization of tumor size, location, relationship to critical brain structures, and patterns of contrast enhancement — which reflect disruption of the blood-brain barrier and correlate with tumor grade. High-grade and metastatic tumors typically show avid ring or nodular enhancement. Advanced MRI techniques including perfusion imaging, MR spectroscopy, and diffusion-weighted imaging provide additional information about tumor metabolism, cellularity, and grade without requiring biopsy. CT scan is useful in emergency settings to detect hemorrhage or herniation. Tissue biopsy — stereotactic needle or open surgical — is required for definitive diagnosis and molecular characterization, which increasingly guides targeted treatment selection.
Tumor Classification
The World Health Organization (WHO) classifies brain tumors by cell type and grade, reflecting aggressiveness and likely behavior:
- Grade I–II (Low grade): Slow-growing tumors with relatively favorable prognosis — examples include pilocytic astrocytoma and most meningiomas. Many are managed with observation and serial MRI.
- Grade III (High grade): More aggressive tumors with faster growth and higher recurrence risk — examples include anaplastic astrocytoma and anaplastic oligodendroglioma.
- Grade IV (Highest grade): Most aggressive primary brain tumors — glioblastoma (GBM) is the most common and carries a poor prognosis despite aggressive multimodal treatment. Metastatic tumors are also managed with urgency regardless of WHO grade.
Treatments
Treatment depends on tumor type, grade, location, and the patient's overall health. A multidisciplinary team including neurosurgery, neuro-oncology, and radiation oncology guides the treatment plan.
For many benign or low-grade tumors — including small, asymptomatic meningiomas — observation with serial MRI imaging is appropriate when the tumor is stable and not threatening critical structures.
Surgery:
Surgical resection is typically the first step for accessible tumors, aiming to remove as much tumor as safely possible while preserving neurological function. Maximal safe resection improves outcomes for most tumor types. Intraoperative MRI, functional brain mapping, and awake craniotomy are tools used to maximize tumor removal while protecting eloquent brain areas responsible for speech, motor function, and memory.
Radiation therapy:
Radiation is used for tumors that cannot be fully resected or that recur after surgery. Stereotactic radiosurgery (Gamma Knife, CyberKnife) delivers highly focused radiation to small, discrete tumors — particularly brain metastases — with high precision and minimal surrounding brain injury. Conventional fractionated radiotherapy treats larger or infiltrative tumors over multiple sessions.
Chemotherapy and targeted therapy:
Temozolomide chemotherapy in conjunction with radiation is the standard of care for glioblastoma following surgery. Targeted molecular therapies and immunotherapy are increasingly used for specific tumor subtypes identified through molecular profiling of biopsy tissue. Bevacizumab (anti-VEGF therapy) is used for recurrent glioblastoma to reduce tumor vascularity and associated edema.
Get an MRI to Confirm Your Diagnosis
Before surgical planning or starting treatment, a clear MRI diagnosis ensures the right path forward. First Look MRI offers self-pay Brain MRI scans — no doctor's order or insurance required — at our locations in Georgia, Texas, and Colorado.