Eli5- Why does cancer predominantly affect organs rather than muscle?


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.