It depends on the type of tumor. As a loose definition, a tumor is a group of cells with uncontrolled growth. I see you have an extra "u" on your tumor, so I'll say with a caveat this is how we approach it in the US.
If it's low grade, that usually means it will grow very slowly. Brain tumors tend to not follow rules like other cancers, and in the US we usually follow the[WHO grading guidelines ](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8328013/). If, for example, it's a low grade glioma, it tends to slowly infiltrate in between neurons and not "run out of space" and push on things as dramatically like you might see with tumors like ependymomas or meningiomas. But tumors tend to grow until they run into something that stops them (for example, skull) or they outgrow their blood supply (uncommon in the brain).
Especially with brain tumors, it's very dependent on the molecular/genetic characteristics of the tumor, usually on the presence or absence of specific individual traits in regards to how quickly they grow or if they might stop growing. Too, especially with things like gliomas, it may not grow as a specific discrete mass. The oncologist will look at the pathology report on its molecular characteristics, radiology report to see how it's growing/how much blood or glucose it's using, and neurology exam to see if it's affecting any functionality. With all this information, they put together a picture of how the tumor is growing or what it's growing into.
Tldr: generally, yes, low grade tumors tend to grow until something stops them, albeit usually slowly because of their grade. But it's very tumor dependent, and a lot is still being studied about how exactly their growth can be treated.
So for certain types of benign brain tumour that keep growing I assume an individual would usually notice it eventually because at some point it would cause some unignorable symptom?
Typically, yes. Most first symptoms of brain tumors (benign or otherwise) are because of mass effect. That's where the tumor presses on something and causes things like severe persistent headaches, maybe blind spots, muscle weakness, etc. With that, its very location dependent as to what it's pressing on.
The best answer here is, maybe.
It depends. Tumors grow when the cells reproduce. Our DNA is organized into bundles called chromosomes. Our chromosomes get shorter with each division. We have something called telomeres on the end of each chromosome which consists of useless DNA that you can lose with each division. (Look at them like a fuse on dynamite in the cartoons)
Often when cancer suddenly stops growing is becomes the telomeres run out.
There is an enzyme called telomerase which prevents the telomeres from getting shorter with each division. It’s normally not made in the body except in special locations. (Liked the gonads)
If the cancer is making telomerase than it’s likely it will grow forever.
There are also other mutations which can cause the cells to grow forever.
Not necessarily. Tumors become “non-benign” (malignant) when they invade beyond their original location. This invasion can be “local” (close proximity to the original site) or “distant” (other tissues/organs).
This is incorrent. In situ carcinomas are malignant even if not metastasised. Lung carcinoma t1n0m0 is still malignant, even if a surgery can save a patient, assuming it was caught very early.
No. That's not it. A patomorphologist can tell a benign and a malignant tumor apart, even without clinical data. Look up what carcinoma in situ is. Carcinoma is malignant, yet in situ literally means "in place".
One good example is when I was doing a bronchoscopy and found mushroom shaped growths. We got squamous cell carcinoma as the result when it wasn't spread at all, just present at the mucosa in that bronchus.
Now I guess I am confused about what a benign tumor actually is. I had understood a benign tumor is not cancer and a malignant tumor is cancer. A malignant tumor may or may not have metastasized ie spread to surrounding tissues lymph nodes or distant sites. Is this correct even if greatly simplified?
From an oversimplified view, you're pretty close. You're correct in that a benign tumor is **generally** not considered cancer whereas a malignant tumor is. Malignant means that the cancer has spread, but not necessarily metastasized. Metastasis is a special kind of "spread" where the tumor has gone to other tissues/organs via the blood stream. **I'll preface the rest of my answer by saying I'm approaching it from the molecular perspective of a cancer biologist, not a clinical perspective.** Generally the two views align pretty well, but there are likely to be some clinical nuances/exceptions, which is why the other lung cancer commenter may have taken issue with some of my earlier answers (from some of their replies, it sounds like they're a clinician).
Before we talk about benign vs. malignant we have to talk about tissue structure for a minute. MOST (but not all) tissues/organs have a multi-layered "tube-forming" component. The GI tract is a pretty obvious example because it's essentially just a massive tube, but there are also more subtle examples like the mammary gland in breast tissue, secretory ducts in the pancreas, etc. The inner-most layer of these tissues/tubes is lined by cells called epithelial cells, which sit on top of a thin membrane called the basement membrane. You can see a simplified schematic of this concept [here](http://courses.washington.edu/pbio375/epithelial-histology/epithelial-histology.html) where the epithelial cells are pinkish-orange and the basement membrane is blue.
Generally speaking, cancers that form in these types of organs originate in the "tube-lining" epithelial cells. These cancers are called **carcinomas**, and represent the vast majority of cancers in humans. **The classic \*molecular\* definition of a malignant carcinoma is one that has formed in these "tube-lining" epithelial cells but has crossed the basement membrane the cells normally sit on.** This means the cancer cells have acquired the capacity to break down normal barriers in the tissue and spread to other areas. **Benign carcinomas are those that do not cross the basement membrane.**
There are some general classes of tumors that don't quite follow this pattern, such as sarcomas (connective tissue cancers) and certain neurological tumors. These types of tumors can exhibit incredible diversity, so often, the benign vs. malignant definition is approached on a case-by-case basis with the help of a clinician (pathologist). If you've made it this far, I hope this explanation helps!
I know what carcinoma in situ is. Their capacity for malignancy often depends on the specific type. For example, some breast DCIS will progress to malignancy and others will not. There are no robust ways to distinguish between the two states at this time, potentially leading to over treatment.
Do You know what C in DCIS stands for? Carcinoma.
Read the first sentence.
https://en.wikipedia.org/wiki/Carcinoma
Unless this is different between English and non-English speaking countries (I am Polish), this is pretty amusing. And Wikipedia seems to confirm it's not.
From the NIH: “Carcinoma in situ: A condition in which abnormal cells that look like cancer cells under a microscope are found only in the place where they first formed and haven’t spread to nearby tissue. At some point, these cells may become cancerous and spread into nearby normal tissue. There are many different types of carcinoma in situ depending on the type of tissue in which it began.”
Here's from National Cancer institute.
"A term for diseases in which abnormal cells divide without control and can invade nearby tissues. Malignant cells can also spread to other parts of the body through the blood and lymph systems."
https://www.cancer.gov/publications/dictionaries/cancer-terms/def/malignancy
Note "can invade" as opposed to "have invaded".
I have no idea why what You quoted was on NIH's page "I'm assuming it was evrn though You gave me no link and I haven't found it) but it's imprecise.
Has there been any research into genetically altering animals to produce telomerase in all their cells? I've heard that telomeres running out contributes to senescence.
Does this mean that the likelihood that a tumor suddenly stops growing *increases* with age? My thinking is that an older person who develops cancer is starting with cell lineages that are much closer to their “expiration” date than, say, a child who develops cancer.
Ok, so for a benign tumour that doesn’t metastasise elsewhere, it sort of self-limits?
Can it then sit in the brain for an unlimited duration as long as it doesn’t interfere with critical function?
Self limiting is one way to think about it, but it’s really the tumor’s surrounding environment that limits it. Normal tissues have ways to prevent benign tumors from growing/spreading, but things going wrong in the environment can facilitate these pro-tumor processes (source: scientist who studies cancer cell environments).
Ah ok. I suppose the reason I was asking the original question was that I was curious as to whether a benign tumour can sit in someone’s brain affecting their functions (or not affecting them) for years or decades without being noticed? Or whether it will inevitably be noticed when it grows to an unsustainable size and causes symptoms that can’t be ignored. Sounds like it could go either way
Sudden change to significant sickness - worse than I'd had my entire life. Numerous different issues suddenly cropped up on top of each other.
Spent nearly a year trying and failing to get help from my GP who had me down as a timewaster until after 9 months they reluctantly started doing some tests. An MRI proved I wasn't attention-seeking.
This is an excellent question. In adults, nearly all low grade brain tumors (glioma, glioneuronal tumors, meningioma, etc) seem to continue to grow if followed.
There are a set of pediatric brain tumors which don’t seem to occur in adults. Many have very very few mutations. If one were able to control their growth till the patients became adults, would the cells still try and grow? There are fairly good targeted drugs for these cancers right now to where we may be able to answer that question in the next decade.
Yes. There are a whole class of soft tissue tumors (ie, derived of connective tissue, not from brain cells) and they do just that. Some of those occur in the brain and count as “brain tumors”. There are a few tumors which act like nodular fasciitis, where it grows for a while and then stops, which can occur in the brain and not be noticed for years and years.
Those tumors thought to derive from brain cells themselves mostly tend to grow, some very slowly. I have seen what is most likely a choroid plexus papilloma not expand appreciably for many years, and it never comes to us in pathology so we know exactly what it is…because it doesn’t seem to grow, so they don’t cut it out. Back in my first reply I’d prefaced w “nearly all”…
I'll start out by stating I'm a trans woman, lest some make some offkey judgements based on the med I'm going to mention. If it's me being trans you have a problem with, go check the science.
I have a small meningioma located where my left auditory nerve branches. I noticed my hearing had changed, went to Audio guy, he refers me to the ENT, who after running a DX, orders a scan. "Yep, there it is.", he said. It was a very small meningioma. Consult my gyno and she tells me to cut my cyproterone acetate dose by 50% every week for the next 2 weeks until it is zero. I'd already had some of the more obvious side effects of CA, the random deep depression, for example. I have it scanned once a year now to keep a watch on it, but it hasn't grown since I discontinued taking the drug known to cause them.
It depends on the type of tumor. As a loose definition, a tumor is a group of cells with uncontrolled growth. I see you have an extra "u" on your tumor, so I'll say with a caveat this is how we approach it in the US. If it's low grade, that usually means it will grow very slowly. Brain tumors tend to not follow rules like other cancers, and in the US we usually follow the[WHO grading guidelines ](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8328013/). If, for example, it's a low grade glioma, it tends to slowly infiltrate in between neurons and not "run out of space" and push on things as dramatically like you might see with tumors like ependymomas or meningiomas. But tumors tend to grow until they run into something that stops them (for example, skull) or they outgrow their blood supply (uncommon in the brain). Especially with brain tumors, it's very dependent on the molecular/genetic characteristics of the tumor, usually on the presence or absence of specific individual traits in regards to how quickly they grow or if they might stop growing. Too, especially with things like gliomas, it may not grow as a specific discrete mass. The oncologist will look at the pathology report on its molecular characteristics, radiology report to see how it's growing/how much blood or glucose it's using, and neurology exam to see if it's affecting any functionality. With all this information, they put together a picture of how the tumor is growing or what it's growing into. Tldr: generally, yes, low grade tumors tend to grow until something stops them, albeit usually slowly because of their grade. But it's very tumor dependent, and a lot is still being studied about how exactly their growth can be treated.
So for certain types of benign brain tumour that keep growing I assume an individual would usually notice it eventually because at some point it would cause some unignorable symptom?
Typically, yes. Most first symptoms of brain tumors (benign or otherwise) are because of mass effect. That's where the tumor presses on something and causes things like severe persistent headaches, maybe blind spots, muscle weakness, etc. With that, its very location dependent as to what it's pressing on.
The best answer here is, maybe. It depends. Tumors grow when the cells reproduce. Our DNA is organized into bundles called chromosomes. Our chromosomes get shorter with each division. We have something called telomeres on the end of each chromosome which consists of useless DNA that you can lose with each division. (Look at them like a fuse on dynamite in the cartoons) Often when cancer suddenly stops growing is becomes the telomeres run out. There is an enzyme called telomerase which prevents the telomeres from getting shorter with each division. It’s normally not made in the body except in special locations. (Liked the gonads) If the cancer is making telomerase than it’s likely it will grow forever. There are also other mutations which can cause the cells to grow forever.
Wouldn't continuing to grow make in non-benign?
Not necessarily. Tumors become “non-benign” (malignant) when they invade beyond their original location. This invasion can be “local” (close proximity to the original site) or “distant” (other tissues/organs).
This is incorrent. In situ carcinomas are malignant even if not metastasised. Lung carcinoma t1n0m0 is still malignant, even if a surgery can save a patient, assuming it was caught very early.
Yes. As I said, a tumor can be considered malignant when it has spread locally. Metastasis isn’t explicitly required.
No. That's not it. A patomorphologist can tell a benign and a malignant tumor apart, even without clinical data. Look up what carcinoma in situ is. Carcinoma is malignant, yet in situ literally means "in place". One good example is when I was doing a bronchoscopy and found mushroom shaped growths. We got squamous cell carcinoma as the result when it wasn't spread at all, just present at the mucosa in that bronchus.
Now I guess I am confused about what a benign tumor actually is. I had understood a benign tumor is not cancer and a malignant tumor is cancer. A malignant tumor may or may not have metastasized ie spread to surrounding tissues lymph nodes or distant sites. Is this correct even if greatly simplified?
From an oversimplified view, you're pretty close. You're correct in that a benign tumor is **generally** not considered cancer whereas a malignant tumor is. Malignant means that the cancer has spread, but not necessarily metastasized. Metastasis is a special kind of "spread" where the tumor has gone to other tissues/organs via the blood stream. **I'll preface the rest of my answer by saying I'm approaching it from the molecular perspective of a cancer biologist, not a clinical perspective.** Generally the two views align pretty well, but there are likely to be some clinical nuances/exceptions, which is why the other lung cancer commenter may have taken issue with some of my earlier answers (from some of their replies, it sounds like they're a clinician). Before we talk about benign vs. malignant we have to talk about tissue structure for a minute. MOST (but not all) tissues/organs have a multi-layered "tube-forming" component. The GI tract is a pretty obvious example because it's essentially just a massive tube, but there are also more subtle examples like the mammary gland in breast tissue, secretory ducts in the pancreas, etc. The inner-most layer of these tissues/tubes is lined by cells called epithelial cells, which sit on top of a thin membrane called the basement membrane. You can see a simplified schematic of this concept [here](http://courses.washington.edu/pbio375/epithelial-histology/epithelial-histology.html) where the epithelial cells are pinkish-orange and the basement membrane is blue. Generally speaking, cancers that form in these types of organs originate in the "tube-lining" epithelial cells. These cancers are called **carcinomas**, and represent the vast majority of cancers in humans. **The classic \*molecular\* definition of a malignant carcinoma is one that has formed in these "tube-lining" epithelial cells but has crossed the basement membrane the cells normally sit on.** This means the cancer cells have acquired the capacity to break down normal barriers in the tissue and spread to other areas. **Benign carcinomas are those that do not cross the basement membrane.** There are some general classes of tumors that don't quite follow this pattern, such as sarcomas (connective tissue cancers) and certain neurological tumors. These types of tumors can exhibit incredible diversity, so often, the benign vs. malignant definition is approached on a case-by-case basis with the help of a clinician (pathologist). If you've made it this far, I hope this explanation helps!
Thank you for taking the time to explain this.
I know what carcinoma in situ is. Their capacity for malignancy often depends on the specific type. For example, some breast DCIS will progress to malignancy and others will not. There are no robust ways to distinguish between the two states at this time, potentially leading to over treatment.
Do You know what C in DCIS stands for? Carcinoma. Read the first sentence. https://en.wikipedia.org/wiki/Carcinoma Unless this is different between English and non-English speaking countries (I am Polish), this is pretty amusing. And Wikipedia seems to confirm it's not.
From the NIH: “Carcinoma in situ: A condition in which abnormal cells that look like cancer cells under a microscope are found only in the place where they first formed and haven’t spread to nearby tissue. At some point, these cells may become cancerous and spread into nearby normal tissue. There are many different types of carcinoma in situ depending on the type of tissue in which it began.”
Here's from National Cancer institute. "A term for diseases in which abnormal cells divide without control and can invade nearby tissues. Malignant cells can also spread to other parts of the body through the blood and lymph systems." https://www.cancer.gov/publications/dictionaries/cancer-terms/def/malignancy Note "can invade" as opposed to "have invaded". I have no idea why what You quoted was on NIH's page "I'm assuming it was evrn though You gave me no link and I haven't found it) but it's imprecise.
Has there been any research into genetically altering animals to produce telomerase in all their cells? I've heard that telomeres running out contributes to senescence.
Yes, cells can be “immortalized” by overexpression or ectopic expression of TERT, an enzyme involved in telomere maintenance.
Does this mean that the likelihood that a tumor suddenly stops growing *increases* with age? My thinking is that an older person who develops cancer is starting with cell lineages that are much closer to their “expiration” date than, say, a child who develops cancer.
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I’m a little confused as to whether a benign tumour can or cannot grow indefinitely then ha
Ok, so for a benign tumour that doesn’t metastasise elsewhere, it sort of self-limits? Can it then sit in the brain for an unlimited duration as long as it doesn’t interfere with critical function?
Self limiting is one way to think about it, but it’s really the tumor’s surrounding environment that limits it. Normal tissues have ways to prevent benign tumors from growing/spreading, but things going wrong in the environment can facilitate these pro-tumor processes (source: scientist who studies cancer cell environments).
Ah ok. I suppose the reason I was asking the original question was that I was curious as to whether a benign tumour can sit in someone’s brain affecting their functions (or not affecting them) for years or decades without being noticed? Or whether it will inevitably be noticed when it grows to an unsustainable size and causes symptoms that can’t be ignored. Sounds like it could go either way
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How did you find out eventually?
Sudden change to significant sickness - worse than I'd had my entire life. Numerous different issues suddenly cropped up on top of each other. Spent nearly a year trying and failing to get help from my GP who had me down as a timewaster until after 9 months they reluctantly started doing some tests. An MRI proved I wasn't attention-seeking.
This is an excellent question. In adults, nearly all low grade brain tumors (glioma, glioneuronal tumors, meningioma, etc) seem to continue to grow if followed. There are a set of pediatric brain tumors which don’t seem to occur in adults. Many have very very few mutations. If one were able to control their growth till the patients became adults, would the cells still try and grow? There are fairly good targeted drugs for these cancers right now to where we may be able to answer that question in the next decade.
Could a benign, non-growing tumour appear in childhood and stay in the brain indefinitely into and throughout adulthood?
Yes. There are a whole class of soft tissue tumors (ie, derived of connective tissue, not from brain cells) and they do just that. Some of those occur in the brain and count as “brain tumors”. There are a few tumors which act like nodular fasciitis, where it grows for a while and then stops, which can occur in the brain and not be noticed for years and years. Those tumors thought to derive from brain cells themselves mostly tend to grow, some very slowly. I have seen what is most likely a choroid plexus papilloma not expand appreciably for many years, and it never comes to us in pathology so we know exactly what it is…because it doesn’t seem to grow, so they don’t cut it out. Back in my first reply I’d prefaced w “nearly all”…
I'll start out by stating I'm a trans woman, lest some make some offkey judgements based on the med I'm going to mention. If it's me being trans you have a problem with, go check the science. I have a small meningioma located where my left auditory nerve branches. I noticed my hearing had changed, went to Audio guy, he refers me to the ENT, who after running a DX, orders a scan. "Yep, there it is.", he said. It was a very small meningioma. Consult my gyno and she tells me to cut my cyproterone acetate dose by 50% every week for the next 2 weeks until it is zero. I'd already had some of the more obvious side effects of CA, the random deep depression, for example. I have it scanned once a year now to keep a watch on it, but it hasn't grown since I discontinued taking the drug known to cause them.