Why do you never hear of someone with calf cancer or bicep cancer but rather cancer affecting the organs or blood?
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Cancer doesn’t grow very well in muscles. It grows and spreads much better in the blood and organs. Also cancer isn’t usually diagnosed until you are symptomatic, which means organs, blood, or bones.
There is “muscle cancer”, namely Leiomyosarcoma (smooth muscle) and Rhabdomyosarcoma (striated muscle), but it is very rare because muscle cells don’t really replicate. Cancer is uncontrolled replication of cells and in adults, muscle cells have lost the ability to replicate for the most part.
Muscle tissue doesn’t really reproduce. A lot of cancers develop in areas where there is a lot of cellular production or reproduction – mucosal layers, skin, etc. Like heart cancer is rare, but possible. In multiple myeloma, it’s not a cell reproducing like crazy but producing a certain protein that is out of control.
Kind of think of it as where there is more activity, more things can go wrong. Most muscle cells, if they do reproduce, it is very slowly, so low chance for cancer. Blood cancers are typically over production of white blood cells, or red blood cells (rarer), lymph cells etc. The problem there is if you try to shut down the cells that make blood cells it shuts down all blood production.
I had a soft tissue sarcoma which is a cancer of the soft tissues. You can see pictures of the whole process if you want on my profile. It was gnarly.
The point is muscle and soft tissue cancers happen quite a bit.
If you don’t count smoking-related lung cancer, some of the most common cancers are actually not in organs. And sarcomas while more rare do start in muscle tissue.
Sure, let’s imagine our body is like a big city, and the cells in our body are like the people living in the city. Now, some parts of the city are very busy, with lots of people coming and going all the time. These are like the parts of our body where cells are always growing and dividing, like in our skin, lungs, or blood.
Now, imagine if sometimes, when people move around the city, they might trip and fall. Most of the time, they can get up and keep going, and everything is fine. But sometimes, they might fall and get really hurt. This is like when cells divide and make a mistake, which can lead to cancer.
On the other hand, some parts of the city are very quiet, with people mostly staying at home. These are like the muscles in our body, like our calves or biceps. Because there’s not much movement, there’s less chance for people to trip and fall. Similarly, because muscle cells don’t divide as much, there’s less chance for them to make a mistake and cause cancer.
So, while it’s possible to get cancer in any part of the body, it’s more common in places where cells are dividing a lot because there’s more chance for something to go wrong.
You only hear about cancer that makes people unwell. Cancer in the brain, blood, chest or abdomen is hidden away and can progress undetected for a long time to the point where it is hard to fix and makes you really sick. You would notice pretty quickly if you developed a tumour in other places like the bicep or calf and in the developed world, get it fixed at a very early stage
Cancer of a muscle tends to be more common in kids. Kids are constantly growing, and there are more opportunities for things to go wrong during their development. A child’s brain grows the most between the ages of 0-2 years, which is why brain cancers are most common in kids of this age group. Bone cancers are more likely to develop when kids tend to have big growth spurts (like when they’re teens).
Muscle cancers are still rare to see even in the world of childhood cancers, but not unheard of.
You have many different kinds of cells in your body. They specialize in different jobs:
– some become blood cells
– some become brain cells (neurons)
– some become muscle cells
– some become antibody (immune system) cells
There are lots of types. Now, each type comes with their own blueprint/instructions to follow and for the most part, they follow those instructions to a T. They tell the cell everything,.from when, how, where to grow, to when to split/reproduce and even, when to die (there are lots of nuances to this, but ELI5).
Cancer as a gross oversimplification is when these instructions go wrong to such a degree that the cell is no longer following a set of instructions that are normal. On any given day, this is happening to millions of your cells inside your body (out of the billions of healthy ones). But in 99% of those cases usually, the bad instructions result in the cell following them to it’s doom. I.e. the bad instructions result in the death of the cell.
But in rare situations, the signal to die is ignored or doesn’t exist anymore and usually the “hey, time to reproduce” signal goes nuts and thus, the cell does what it is told to do, go nuts and reproduce.
Now, here’s the thing: this can happen in ANY kind of cell in your body whatsoever.
So back to your question: let’s say, I pick a cell type that’s capable of rapid reproduction/splitting and I give it a set of instructions that tell it to not die (and none of its children will naturally either) and to reproduce like crazy. It’ll do exactly that, wherever it happens to be in the body. And because it can reproduce fast, it can get damaging (think of a lump growing in a critical artery) before you even know it’s there.
Now, that can happen too in say, a muscle cell, but because it is either an extremely slow reproducer OR doesn’t reproduce at all, it becoming cancerous just isn’t the same danger because even if it was, it would take so long to grow into something dangerous that you’ve most likely died of some other cause. Also note that your immune system regularly spots and destroys cancerous cells too.
Remember, everyone has cancer, all the time. It’s a normal consequence of every cell having their own instructions without a safe ‘gold record to compare it against’. We only call cancer out as a condition when it becomes detectable as something that will kill you quicker than other things.
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