“*A carcinogen is a substance, organism or agent capable of causing cancer*”.
“*Cancer* is *a disease in which some of the body’s cells grow uncontrollably and spread to other parts of the body*”.
How does something like alcohol or tobacco cause cancer?
In: Biology
ELI5 – when something is a *carcinogen* it’s like a gun that fires at your DNA. The chemical can hit the extra “junk” DNA that doesn’t do anything**, hit a part of your cells (e.g. the mitochondria) or your DNA. Even then one hit could make a harmless change or the cell just up and dies because the DNA can’t function anymore.
That’s one “shot” from something that can cause cancer. The less your exposure, the more the odds are in your favor.
Smoking or drinking is repeatedly exposing yourself to that “gun”. Now the odds are NOT in your favor. The more you’re exposed, the more at risk you are of a harmful change to your DNA turning cells into cancer cells.
What do I mean by a “harmful change”?
DNA is the instructions on how to make proteins and governs how cells divide.
But in ELI5 terms – the sentence “The fat cat ate the rat” has meaning right?
Now let me replace and remove some letters: “The bt caa ale the raq” – that’s nonsense.
And if I do it again “The fat bat are the rat” it’s nonsense but it you can read it.
Just as inserting nonsense lines in a paragraph or sentence can confuse you, if sequences of your DNA are damaged or changed, your cells can go haywire as the regulator systems are broken because the “sentence” that controlled them is now nonsense.
No imagine this change happening all over your body’s DNA – in effect the “gun changes the words” all over your DNA when you’re exposed over and over again to cancer causing chemicals. Sooner or later your luck runs out and what was a healthy cell now becomes a cancerous mass as it goes haywire and won’t stop growing.
**=that’s another ELI5
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