Low-grade glioma

What people mean by low-grade glioma, and why it is not one diagnosis. Why grade 1 and grade 2 are not the same thing at all. Watch and wait, and what changes over time. And the questions worth asking about your own result.

The short version

"Low-grade gliomaglioma: A tumor that starts in the glial cells. Those are the support cells of the brain and spinal cord. Gliomas are given a grade from 1 to 4. The grade says how the tumor is expected to act. See the glossary" is not one diagnosis. It is a label covering a lot of different tumors that happen to grow slowly. The most important thing on this page is that grade 1 and grade 2 are not the same thing, and being told "low grade" without being told which one leaves you with the wrong picture. Many of these are treated by watching first rather than acting at once, and that is a real plan. Your actual diagnosis, the one on your report, is what everything else depends on.

What is a low-grade glioma?

It is a phrase doctors use for a glioma that grows slowly. It is not the name of a tumor.

That matters more than it sounds. The label covers a couple of dozen different tumors. They do not all behave the same way. That is why the World Health Organization advised against using the term even before the rules were rewritten in 2021. You will still hear it constantly. That is why this page exists.

So the first thing to do is find your real diagnosis. It is on your pathology report, and it will be a specific name with a grade attached, like "astrocytoma, IDH-mutantIDH gene change: A small change in a tumor's IDH gene. It is the first thing your team looks at when naming an adult glioma, and it can affect which treatments are offered. Your pathology report says whether your tumor has it. See the glossary, CNS WHO gradeCNS WHO grade: A number from 1 to 4 for how a tumor is likely to behave. Since 2021 it is written in plain numbers, not Roman ones. Gene results can set it too. See the glossary 2". Your pathology report, part by part shows you where to look. Once you have that name, it is worth more to you than anything on this page.

In adults, two names sit under the label more than any others. One is astrocytoma, IDH-mutant, grade 2. The other is oligodendroglioma, IDH-mutant and 1p/19q-codeleted, grade 2. Children and young people have their own set of names. Pilocytic astrocytoma is the one you are most likely to hear there.

You may also come across "lower-grade glioma", with the -er. Some doctors use that for grade 2 and grade 3 together. It is a different grouping again, and it is worth asking which one somebody means.

The rules for naming brain tumors changed in 2021. If your paperwork was written before that, some of its words are no longer used.

This matters more than it sounds. People read an old report next to a new one, see two different names, and think somebody made a mistake. Usually nobody did. The tumor did not change. The way doctors write it down changed.

Three changes affect almost every report.

• Roman numeral grades, such as grade II or grade IV on an older report. These are now written with ordinary numbers instead: grade 2, grade 4. Nothing about the grade itself changed. Only the way of writing it did.
• Gene results are now part of the name. Older reports named a tumor mostly by how the cells looked. A name written now usually has a gene result built into it. That is why a newer report can look longer and more technical than an older one about the same tumor. You may also see NOSNOS: Short for "not otherwise specified". It means the gene tests needed to name the tumor fully were not done or could not be done. Ask your team whether they can be. See the glossary or NECNEC: Short for "not elsewhere classified". The tests were done, but the results do not match any named tumor type. Ask your team what it means for your plan. See the glossary written next to your diagnosis. These say something about the testing, not about how serious the tumor is. NOS means the tests needed to be more exact were not available. NEC means testing was done, but the results did not fit any defined group neatly.

Seeing an older name on your own report does not mean it was wrong. It means it was written under the old rules. If you are holding an old report and a new one and they do not match, that is a good thing to take to your team and ask about.

Two older names turn up on this group's paperwork more than any others.

• Diffuse astrocytoma on its own is now usually written with the gene result attached, as astrocytoma, IDH-mutant, with a grade.
• Oligoastrocytoma, a mixed name, is no longer given as a diagnosis. Gene tests now sort those tumors into one group or the other.

Seeing a retired name on your own report does not mean it was wrong. It means it was written under the old rules. If you are comparing an old report with a new one, ask your team to walk you through what changed and what did not.

Is it cancer? What does the grade mean?

This is the hardest section on this page and it is the reason the page is written at all. It has two answers, and which one is yours depends entirely on your grade.

Most grade 1 gliomas are a different situation. Doctors call them circumscribed. They have an edge. They sit apart from the brain around them rather than growing into it. That is why an operation that takes all of it out can often cure them. Pilocytic astrocytoma is the usual example.

Grade and growth pattern are two separate things, though, and they do not always line up. Some grade 1 tumors in children are diffuse. So ask about both.

Grade 2 diffuse gliomas are not that. They grow into the brain around them rather than pushing it aside, which means there is no edge to cut around. They are malignant, and with today's treatments they are not curable. That is a hard sentence and it is here on purpose, because the alternative is worse.

Here is why it is here. A brain tumor doctor wrote about this. The article describes the shock on people's faces at being told what a grade 2 glioma is. Many had already been told something else, before they ever reached a cancer specialist. They had been told it was curable, and maybe not even cancer. The phrases they repeated back were "this is the good kind", "we got it all", and "this is the best brain tumor to have".

If somebody has said something like that to you, they were not lying to you. They were probably thinking of grade 1, or reading a scan that genuinely looks undramatic. But you deserve to know which of the two you have, and you are entitled to ask the question plainly: is mine grade 1 or grade 2, and is it circumscribed or diffuse?

None of this means what happens next is fixed. Not curable is not the same as not treatable, and it is not a timetable. What it means is that this is a long relationship rather than a single event, and that changes what good care looks like. There is a section further down about how that tends to go, behind a choice, so you can read it when you want to and not before.

What the grade on your report means goes through the grading itself.

Why does my report say grade 4 when the scan looked low grade?

Because since 2021, the grade does not come only from what the cells look like.

For some tumors, a gene result now sets the grade on its own. It does that even when the cells look low grade under the microscope.

Here are the two that trip people up. A tumor that looked grade 2 down the microscope is called glioblastomaglioblastoma: A glioma that is given grade 4. Grade 4 is the highest grade there is. The tumor grows fast. Treatment usually starts soon after it is found. It often means surgery, and then radiation and chemotherapy. See the glossary, grade 4 if it is IDH-wildtype and carries certain gene changes. And an IDH-mutant astrocytoma is grade 4 if it has a CDKN2A/B deletionCDKN2A/B homozygous deletion: Both copies of two genes that put the brakes on cell division are missing. The two are CDKN2A and CDKN2B. See the glossary with both copies gone, even when it looks nothing like a grade 4.

This is one of the most frightening things that happens to people here. It usually arrives with no warning. The scan looked mild. Everyone sounded cautiously reassuring. Then the report says grade 4.

It is not a mistake, and nobody was hiding anything. The gene results took longer to come back than the first impression did. And they carry more weight.

The words on your gene results takes IDH, CDKN2A/B and the rest one at a time. If this has happened to you, that page and a conversation with your team are the two things worth having.

Where does it grow, and why does it cause these symptoms?

In adults, grade 2 diffuse gliomas are usually in the upper part of the brain. Your team may call that supratentorial. It is the part that handles movement, speech, feeling and thinking.

A slow tumor causes trouble differently from a fast one. It grows a little at a time, so the brain around it adapts as it goes. That is why a tumor can look large on a scan while the person feels mostly fine. It is also why the early signs get put down to stress, or tiredness, or getting older. Sometimes for years, before anyone scans anything.

It is also why these tumors often show up less dramatically on a scan than a faster-growing one. They usually do not light up when dye is used. Your MRI scan goes through what the dye is doing.

Which part of the brain, and what that changes. This page says the upper part and stops there, because that is as far as the sources it uses go. Where your tumor is, and what that changes names each part in plain words and in the words a report uses. It also sets out the five things a team can land on about an operation. And it says why it will not rank one place against another.

What symptoms does it cause?

Seizures are the big one. A seizure is often the first sign of a low-grade glioma. If a seizure is what brought you here, you are in very ordinary company.

Other things people notice, usually slowly: headaches, trouble finding words, changes in how sharp or organized thinking feels, weakness or numbness on one side, and changes in vision.

Some of these tumors are found by accident. Someone has a scan for a head injury, or for a headache that turns out to be nothing to do with it, and there it is.

When to call for help right now

Some things should not wait for the next appointment.

Call an ambulance for any of these. Call 911, or your local emergency number:

• A first ever seizure.
• A seizure that lasts more than five minutes.
• One seizure right after another, with no waking up in between.
• Someone who cannot be woken.
• Trouble breathing, or someone who seems to be choking.
• Suddenly not being able to speak, move one side, or see.

A seizure like the ones you usually have, that stops on its own, is not an ambulance call. What to do during a seizure draws the line.

Call your team the same day for any of these:

• A headache much worse than usual, or one that wakes you from sleep.
• Throwing up again and again.
• New weakness in the face, an arm or a leg.
• New trouble speaking, or understanding what people say.
• New confusion.
• Sleeping much more than being awake.
• A sudden change in your vision.

If you are having chemotherapy, a fever is its own rule. It means calling your team right away, at any hour, not waiting for the morning. An infection during chemotherapy can get dangerous fast, and it is treatable when it is caught early. The fever rule explains why, and what number your team will give you.

In the weeks after brain surgery, a fever is its own rule too, especially with a stiff neck or a bad headache. What comes after a craniotomy has the rest of that list.

If you have a shunt, the signs it has stopped working are their own rule. For you, everything on the same-day list above is a right-away call instead, and so are a few other signs. Get help right away, at any hour: call your team, or go to the emergency department. Signs a shunt is not working has the full list.

If you are not sure whether to call, call. Nobody on that team minds a phone call that turns out to be nothing.

Same day means today, not the next clinic appointment. Ask your team now for the after-hours number, and put it somewhere you will find it at two in the morning rather than somewhere sensible.

What to do during a seizure has the step-by-step, and getting help now is the short version to keep on a phone.

How do doctors find out it is this?

A scan first, then tissue. A scan can suggest a glioma and can suggest it is slow-growing, but only a piece of the tumor, looked at in a lab, can name it. For these tumors, the gene tests are what settle both the name and the grade.

• Your MRI scan for what the appointment is like, and what the dye is for.
• How tissue is taken for the needle, the operation, and what happens if the sample does not give an answer.
• Waiting for your pathology results for why the answer comes in layers, and why the name can change while you wait. That applies particularly here.
• Your pathology report, part by part for the document itself.
• The words on your gene results for IDH, 1p/19q1p/19q co-deletion: Two pieces of two chromosomes are gone. They are gone from the tumor cells. A glioma can have this change. If it has an IDH gene change too, it is called an oligodendroglioma. See the glossary, CDKN2A/B and the others.

What do the words on my report mean?

The three that decide most of what happens next:

• IDH. Whether the tumor carries a change in the IDH gene. For an adult diffuse gliomadiffuse glioma: A glioma whose cells spread out into the brain around it instead of staying in one lump. That is why the edge on a scan is not a clean line. See the glossary, this is the first fork in the road. It is also what makes vorasidenib possible later.
• 1p/19q. If this is co-deleted and there is an IDH change, the tumor is an oligodendroglioma. If it is not, an IDH-mutant tumor is an astrocytoma.
• CDKN2A/B. If both copies are gone in an IDH-mutant astrocytoma, the grade is 4. That holds however the cells look.

You may also see ATRXATRX: A gene checked on the pathology report. The tumor cells may or may not still make the ATRX protein. Which one it is helps sort a glioma into one type or another. See the glossary, TP53TP53: A gene checked on the tumor tissue. Whether it has changed is one of the findings used to name an astrocytoma. Ask your team whether the change they found was in the tumor only. See the glossary, Ki-67Ki-67: A stain that shows how many tumor cells were dividing when the sample was taken. The report gives it as a percentage. It is read together with everything else, not on its own. See the glossary and MGMTMGMT promoter methylation: MGMT is a gene whose protein repairs damage to a tumor's DNA. Methylation turns it down. Your report says how much, and your team uses that when they choose chemotherapy. The line between high and low is not settled. See the glossary. Each has its own entry on the words on your gene results, which is where they are explained properly rather than in passing.

How is it usually treated?

There is no single answer here. Your plan depends on your grade, your gene results, where the tumor sits, how much of it came out, and what you want.

• Surgery, taking out as much as is safe. This is usually the first step where it is possible. For a grade 1 circumscribed tumor, a complete operation can be the end of it. Brain surgery: what happens, and what comes after goes through the operation. If the tumor is close to the parts that handle speech or movement, you may be awake for part of it. Awake brain surgery explains why.
• Watching, with scans. Your team may call this watch and wait, or active surveillance. It is a real option for some people, and there is a section on it below, because it is the part that causes most doubt.
• Radiation, usually after surgery, for people whose situation suggests treating now rather than waiting. Radiation therapy: the mask, the daily visits, and what comes after goes through it. If somebody has raised proton therapy with you, that page explains what is different about it, and why it is a fair question here even though the trials that would settle it have not been done.
• Chemotherapy, usually PCVPCV: Three chemotherapy drugs given together: procarbazine, lomustine and vincristine. It is the usual choice after radiation for an oligodendroglioma. See the glossary after radiation in this setting. Chemotherapy: the drugs, your blood counts, and the fever rule takes the drugs one at a time.
• Vorasidenib, a newer medicine taken by mouth, for some people. Its own section below, and what the trial did and did not study if you have already had radiation or chemotherapy.
• Seizure medicine, which for many people here is not a side issue but one of the main goals of treatment.

Why is my team suggesting we just watch it?

Because for some people, watching is the treatment that does least harm.

Watching is not doing nothing. It means scans at set times, and seeing your team, so a change is caught while it is small. Here is the point of it. Radiation and chemotherapy both have costs. Over years, radiation's cost falls on thinking and memory. Starting radiation right after surgery can hold the tumor back for longer and mean fewer seizures. Even so, it has not been shown to change how long people live. That is why some teams wait, to put radiation's cost off until it is needed.

Whether it suits you depends on things your team can weigh and a web page cannot: your grade, your gene results, how much of the tumor is left, your symptoms, and how you feel about it.

One thing worth knowing, because it gets misused. You may hear about an age line around 40, splitting "low risk" from "high risk". That line came from a clinical trial. It was written to decide who could join the trial. It was not written to decide who needs treatment.

The researchers who use it say so plainly. There is no clinical reason for a strict age cutoff, and other things should be weighed too. So if your plan has been explained to you as "you are over 40, so...", ask again. Not because anyone is wrong. Because the reasoning should be about you.

Waiting is hard, and being uneasy about it is not a sign you are choosing wrong. Ask what specifically would change the plan, and when the next scan is, so you know what you are waiting for. Watching a tumor, step by step goes through the plan itself, and the worry that can come with it.

What is vorasidenib, and could it apply to me?

It is a medicine taken by mouth, for some people with a grade 2 IDH-mutant glioma. It is the newest thing on this page by a long way.

The FDA approved it in August 2024. It is for adults and children aged 12 and over. The tumor has to be a grade 2 astrocytoma or oligodendroglioma with an IDH change, and there has to have been surgery first. A biopsy counts as surgery here. It works on the IDH change itself. Chemotherapy works a different way, by going after cells that are dividing.

Two reasons to ask about it by name. It is new enough that a lot of patient information written before mid-2024 does not mention it at all. And it turns entirely on your IDH result. That is exactly the kind of detail that can sit in a report with nobody talking it through with you.

So ask two things. Does my tumor have an IDH change? Am I someone vorasidenib could apply to? If the answer is no, ask what that is based on. It is a specific question and it has a specific answer.

What is treatment actually like, and what is normal afterwards?

The library pages go through the day-to-day of each one. What the operation involves, and the weeks after it. What a course of radiation is like from the inside. What chemotherapy does to your blood counts.

Two things that are particular to this group:

Seizures often get better with treatment. Treating the tumor is often what brings the seizures under control. So here, seizure control is one of the goals of treatment. It is not a side effect of it.

"Is this the tumor, or the medicine?" is a question worth keeping in your pocket. The medicines used here have effects that look like the tumor getting worse: levetiracetamlevetiracetam: A medicine that helps stop seizures. Many people with a brain tumor take it. In some people it also brings a short temper, anger or low mood. Tell your team if you notice that. See the glossary is linked with irritability and low mood, and steroids cause muscle weakness. Steroids and anti-seizure medicines cover those two on their own, and the surgery and radiation pages go through the rest.

Everyday life: work, driving, seizures and tiredness

People with a low-grade glioma are often living an ordinary life around it, sometimes for a long time. So the practical questions matter as much as the medical ones.

Seizures and driving. Driving rules after a seizure depend entirely on where you live, and this page will not guess at yours. Ask your team, and ask early, because it is one of the changes people find hardest and one of the easiest to plan around once you know. Living with seizures goes through the rest of it: what is safe, what to change, and how much of the usual advice turns out to be wrong.

Work. Many people keep working. Whether you can, and in what shape, depends on your symptoms and your job rather than on your diagnosis.

Tiredness and thinking. Both are common. Both are easy to blame on the wrong thing. Raise them rather than putting up with them. If your thinking feels different, say so. Your team can test it. You do not have to prove it first. What that testing involves sets out both the quick exam and the longer one.

Follow-up scans, and what to do while you wait

Scans continue whether or not you are having treatment, and for a lot of people here they are the treatment plan.

Even after a complete-looking operation, scans continue. For a diffuse glioma, cells extend past the edge of what shows up on a scan, so "we got it all" describes the picture rather than the tumor. That is not a reason to think the operation failed. It is the reason for the scans.

The wait before a scan result is its own thing, and for many people it is worse than the scan. Ask who will give you the result, and roughly when. Ask one more thing: will it appear in your online records before anybody calls you? For a lot of people it does.

Follow-up scans, and what the results mean goes through what your team compares each scan with, and what the words on the report mean.

If it comes back, or changes

Because a diffuse grade 2 glioma is not curable, the plan assumes it will need attention again at some point. That may be many years away. It is the reason the scans do not stop, and it is built into your follow-up from the start.

Some of these tumors change into a higher grade over time. That is what people mean by transformation. It is a known behavior of these tumors, not a sign that something has gone wrong. It is one of the things your team looks for on each scan.

There are no numbers about it on this page, deliberately. What is worth knowing is what it would change: the plan, not the fact that you have a plan. If it happens, the treatment options are the ones on this page, in a different order.

Tell your team if something changes between scans. New or different seizures. New weakness. A headache that is not like your usual one. Do not wait for the next appointment. Bringing a scan forward is a normal thing to do.

Did I cause this?

Almost everybody asks this, usually in the first week, usually in private. It is worth answering plainly.

For most brain tumors, nobody knows the cause. That is the honest state of it. The exact cause of most brain and spinal cord tumors is not fully understood, and there are very few well established risk factors. Tumors start when genes that control how cells grow and divide are changed, and in most cases those changes happen by chance during a person's life. Not because of something done or not done.

Cell phones. They give off a kind of radiation called radiofrequency. It is not the same as the radiation in an x-ray. The energy is too low to damage DNA, and it is not known to cause cancer. The evidence so far is that using a cell phone does not cause brain tumors.

Stress. There is no scientific evidence that stress causes brain tumors, and no data linking stress to a higher chance of getting one. A hard year before a diagnosis is a hard year. It is not a cause.

Something you ate, or did not eat. No food and no diet is an established cause of a brain tumor. It is not on the list of known risk factors at all.

Something you passed on, or caught. Brain tumors are not contagious. Most are not inherited either. A small number of people do have an inherited condition that raises the risk, and if that applies to you, your team will raise it and offer to talk it through.

If you are turning this over at three in the morning, that is ordinary and it happens to nearly everyone. It is also worth saying out loud to somebody on your team, because they have answered it many times and they would rather you asked.

What might happen over time

For the person caring for someone with this

If you are the one driving to the appointments, keeping track of the pills, and lying awake at night worrying about them, this part is for you.

You are allowed to ask questions. In one study, families said they were afraid of annoying the doctor by asking too much. One of them was told by a doctor to stop playing doctor. Ask anyway. Write your questions down before you go, and bring a notepad. Two people in the room hear more than one.

Ask who your first call is. Care comes from a lot of people at once, and it is easy to end up as the only one holding it together. Ask the team: who do I call first? Some teams have one person whose job this is, often a nurse. Get the name and the number.

Get two numbers, and know which one to use. One for work hours, one for nights and weekends. Then ask what counts as "call us today" and what counts as "call an ambulance" for this tumor, and write the answer down where you can see it. If you are not sure which it is, call. Nobody on that team will mind.

If they have seizures, read about them before you need to. What to do when someone has a seizure is the one to know by heart. Living with seizures is about the rest of the time: what is safe, what to change, and driving.

Ask to be shown anything you are sent home to do. In that same study, families were sent home to change dressings and give medicines with no training at all. That is not fair to you. Before you leave the hospital, ask someone to show you. Then do it once while they watch.

Say what you notice. You may see a change before they do. Changes in thinking, mood and behavior can show up to the people close by first. Telling the team is not going behind their back. It is something the team cannot learn any other way.

Look after yourself, and let people help. Eat, sleep, and keep your own appointments. Take a little of the day back for yourself. When someone asks what they can do, give them a real job: a meal, a ride, an hour with the kids. Most people want to help and do not know how to offer.

You can talk to somebody about all of this today. See where to get help.

What is different about this one is the timescale. This is not a few hard weeks and then recovery. Here it is usually years of living alongside something, and that asks something different of you.

Seizures are the thing to be ready for. If seizures are part of this, learn what to do before you need to. What to do when someone has a seizure is the one to know by heart, and it says which seizures need an ambulance and which do not. Knowing that difference is what stops every event becoming an emergency.

Scan weeks are hard, and they come around again. The days before a follow-up scan and its result are, for a lot of people, worse than anything else in the year. It helps to know that in advance and to plan the week rather than pretend it is ordinary.

Watching is hard to live with, for you as well. If the plan is to watch, there is nothing for you to do. Having nothing to do, while something frightening sits inside someone you love, is its own kind of hard. It is not a sign the plan is wrong.

The changes you notice may be the ones nobody else does. Tiredness. A shorter temper. Words coming more slowly. Thinking that seems a step behind. You will see those long before a clinic appointment does. Say them out loud at the appointment. They can be tested, and some of them turn out to be the medicines rather than the tumor.

Plan for the long version. Whatever is happening this month, this is not an event to get through. It is something to live alongside. Look after your own health. Keep your own appointments. Let people help with the ordinary things.

What to ask your team

• Is mine grade 1 or grade 2, and is it circumscribed or diffuse?
• What is my exact diagnosis, in the words that are on the report?
• Does my tumor have an IDH mutation? What about 1p/19q and CDKN2A/B?
• Are we watching it or treating it now, and why that?
• What specifically would make us change the plan?
• When is my next scan, and who will go through it with me?
• Am I someone vorasidenib could apply to? If not, what is that based on?
• If surgery is on the table, what is the goal, and what could I lose?
• What should I do about driving and work?
• What should make me call you before the next appointment?
• Is there a clinical trial I should know about?

Where to get support

• Get help now if you want to talk to a person today.
• Living with seizures for the practical side of seizures over the long run.
• What to do when someone has a seizure, worth reading before you need it.
• Brain surgery, radiation therapy and chemotherapy for the treatments themselves.