How is the growth of benign tumors suppressed?

Question

A benign tumor has an outer layer of cancerous cells beyond which are regular cells (I Think). The Tumor must have some kind of boundary layer like a wall where somehow the cancerous cells can't affect any more normal cells outside the *wall*. A Benign Tumor I think can be inactive for many months; it might never grow anymore. Might it be that the cancer cells at this *Benign Tumor Wall* are inhibited from affecting any more cells? Could there be an Apoptosis shut-off inhibitor or a cell-death pathway shutting-off inhibitor in this case?

Answer 1

Great question! Cancer cells typically aren't "affecting" other cells in a traditional, infection-by-contact way. I.e. cancer does not typically grow by touching other cells.

Instead, cancer cells act like they are immortal (they nearly are), and they just keep copying themselves. Normal cells have a senescence limit - they copy themselves a few dozen times, the protective telomeres on their chromosomes run out, and they die. Cancer cells upregulate their telomerase to keep extending the telomeres, turn on their "COPY ME" signals, turn off their "safety checkpoint" features, hide from the immune system, inhibit the apoptotic signals, and they just copy, copy, copy, copy themselves. This is how tumors form.

If they have the right mutations, they develop the ability to break off cells and float to a new place in the body: this is metastasis.

The body has lots of ways of limiting or removing benign masses - these are not cancerous though. Benign tumors lack the unlimited self-copying and breakaway abilities of cancers. (That's why they're benign!)

Best of luck with your studies!

Matt