system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Is there a difference between types of cancer other than location?

Breast cancer, brain cancer, pancreatic cancer, skin cancer, etc...  Are they all the same thing just indifferent locations, or are they biologically different?  I know different things cause different cancers, but is it exactly the same disease just in a different body part?  And if they aren't related like that why are they all called cancer?
gpt
Yes. If your body is a company and every cell is a worker, cancer is a worker gone rogue. One day he decides he isn't going to do his job, destroys a part of the company and grabs a gun to prevent being kicked out. Every day, he destroys more stuff (unregulated growth). 

If he's a low ranking worker, he doesn't have all the keys so he can only close the doors from where he works (the tumor grows, but it can't invade other organs). That's a **benign** outcome, nuke his division and you eliminate the rogue worker. If he's the CEO, he has access to the whole company. He may decide to destroy the internet servers or the bathrooms. That's a **malignant** cancer, it can invade other organs. If the damage is too big you are screwed. If you catch it early, you may stand a chance.

But that's not all, every worker has a different personality and a different job. The guy from IT doesn't close doors, he likes to put porn on your computer (it secretes hormones you don't need). A janitor won't cause the same damage as the guy from accounting (a tumor in your chest won't cause you the same problems as a tumor on your stomach). One CEO is dumb and writes "THE CEO RULES!" (you have symptoms and can detect it early), but another one is more subtle, he only destroys the rooms nobody uses, but once you realize what's going on there aren't any more conference rooms (you are asymptomatic until it's too late).

Now imagine there's something wrong in the bathroom. With only that information you can't know if it was the janitor (benign) or someone higher up in the chain of command who has access to the bathroom (metastasis: it spread from another sector). So what do you do? A closer scan reveals that the "something wrong" was a computer with porn stuck on the toilet. Now you can safely assume it was the guy from IT, right? But how do you stop him? Since not all workers cause the same kind of damage, the same strategies won't work on every worker (different treatments). For the IT guy, you have to cut his access to computers. For the CEO, you have to carefully reduce his influence and then fire him. For the janitor who only has the key to one bathroom, just destroy the bathroom.

I hope that analogy wasn't too ELI5.