When Dawn Dies Down

Metastasis

"Metastasis," The biology teacher knocked at the word on the board, awakening Irwin who was just about to fall asleep, "the spread of cancer cells from where they first formed to another part of the body. Slow, but deadly." He stopped and coughed. "Just remember, one single cancer cell can corrupt an entire body with metastasis. It will slowly but steadily spread, through your veins and lymph. You may be able to slow it down even more, but no, never will it be curable. So, lesson of today? Never let one cancer cell enter your body. Now, can someone tell me, what are the causal factors of cancer? Why don't you answer, Irwin? You seem eager to learn.
Irwin sighed and was about to say no, but realized just how many eyes were staring at him.
"Well, sir, umm, unhealthy lifestyle, I guess. Like smoking and drinking and doing drugs, or even constantly staying up late at night." He answered.
"Very well," The teacher approved, "but you know, sometimes cancer cells just like to be inside you for no reason. Absolutely no reason. In that case, you are really, really lucky. Homework time! I want an essay from all of you, on the causes, process, symptoms and impact of cancer, about 1000 words, due on next Monday. Take care of yourselves and don't let no cancer go near you. Class dismissed."
The final two words were like a charm. All students, no matter paying attention or not, had left their seats, running out of the classroom like flies.
Irwin stood in front of his locker, thinking of nothing. On his right side there came some clear chattering.
"I can't believe he gave us homework on one of the dumbest topics. Cancer! Mesa tasty or whatever it's called! Who cares? And it's even an essay! Such waste of time."
"I know right. The biology teacher is always mad. Can't change that."
Irwin let out a sigh and turned away.