Not sure if this is the place but what IS cancer? Like how does it start what forms the lumps and why does it spread?

r/eli5

Cells use up nutrients in your body to divide a few times and then die off. This is a strictly controlled process to you don't end up with more cells than you need. If there's a problem with this process where your cells divide uncontrollably and don't die off, the growth turns into a lump, a tumor.

Cancer is a mutation that takes place in the DNA of a cell and causes uncontrollable cellular growth. This is what creates a tumor. Tumors spread when the cancer cells attack other cells; thus infecting them with the mutation and causing more uncontrolled cellular growth.

It takes a lot of different forms and can behave in a lot of different ways. Over simplified it’s when some of your cells don’t get the signal to stop replicating and they pile on top of each other forming a mass. The mass can then rupture and spread cells to other parts of the body that then take root and repeat the process.