How can things like sunburns and smoking still increase risk for cancer decades after their damage has been done to the body?
In: Biology
UV rays, wich causes sunburns, and certain components in tobacco smoke cause damage to the DNA. If DNA gets damaged, it is like a scratch on a CD and information (aka building plans for all the stuff your body is made of) are not read correctly. Those replication errors happen all the time, but normally the replicated cell realizes that it is a potential danger for the organism and requests a bullet to the head (that is called programmed cell death or apoptosis).
But that is not the only safeguard, your DNA contains structures called telomeres. Telomeres are long strands of basically monotone nonsense, they do not contain any useful information. Their job is it to stabilize the chromosome (that is how DNA arranges itself. Those telomeres are not infinite though, they are like a sacrificial protector. With time, they get shorter and shorter. Or damaged, like through toxic fumes or high energy radiation (like UV). The shorter they get, the less protection the chromosome has. So when I smoke like a badly tuned bbq through my teenage years and 20s, I destroy more telomere than what just getting old would. So the protection could be used up by the time I would be 45 instead of 105.
Even when I stopped smoking at thirty, the damage is already done.
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