My plan

I've got a few different theories and ideas about how cancer can and does move throughout the body vastly unhindered. The first,and most relevant, is that cancer cells either mimic or invade blood cells to moves to and fro within the body. The other theories are as of now undeveloped. Fast moving cancer cells go only short distances therefore they don’t need to leave the main tumor hub. Slow cancer cells on the other hand use Invadopodia to get into the blood vessels the slow cancer cells can move about as far as they want, Invadopodia is the tendrils slow moving cancer cells generate. These tendrils can slice their way through the fiber wall made by collagen, similar to how a scalpel can cut through skin, leaving a sealable hole that isn’t noticeable.

That’s what leads me to believe that these slow cancer cells can “hitchhike” on the blood cells.