3 ms·

It can't possibly be linear like that, right? Also, I swear the mechanism behind smoking causing cancer is that cells have a different division mode for rapid

It can't possibly be linear like that, right? Also, I swear the mechanism behind smoking causing cancer is that cells have a different division mode for rapid healing and it's more prone to copying errors than normal cell division. Some of these copying errors break the replication inhibition mechanism, and then you have the accepted thing where some errors are caught by the immune system and eventually you get unlucky and some aren't. This pattern applies to every cancer that I know of (where healing in the case of smoking is tiny burns healing over and over and over again).

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irjustin 2y ago
Actually, doesn't it have to be linear? I'm having trouble looking up the exact study, the link they provide doesn't actually link the study. But if I were to structure an observational smoking study, I basically track smokers vs non-smokers from the same population. Hope that my n is big enough and then simply track years non-smokers lived longer vs number cigs smoked. Thus linear. Help me - because I can't imagine a different way to run this.
- randomNumber7 2y ago
  In medicine is often a threshold effect. Only if you cross some threshold, harm is done. I can not imagine that someone who smokes a few cigarettes in their 20s loses the same per cigarette as someone who smokes for years.
  - chithanh 2y ago
    To be more precise: It is not so much a (dose) threshold but how much margin/reserves your body still has. For example kidney injury is progressive, and by the time the kidney's functional reserve is exhausted, things will remain bad until death or kidney transplant. Also for diseases like HIV/AIDS, the cognitive reserve influences how long it takes until HIV associated dementia sets in.
  - irjustin 2y ago
    >I can not imagine that someone who smokes a few cigarettes in their 20s loses the same per cigarette as someone who smokes for years. Realistically even in a large enough sample set you won't see a "jump" or "cliff". It'll just look like blurry data. At some point, you'll be like obviously this is making a difference, but it'll be this very wide band and putting drawing a line will never be right. You'll end up saying something like >500-12,000 smoked means X minutes per cig. The band will be so sloppy it's better to just go linear and say an overly simplistic answer.
- deleted 2y ago
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isaacfrond 2y ago
I can well imagine a (first order) linear effect. Inhaling toxic fumes gives a probability p that a cell is harmed into a cancer cell. The probability of a hit after n trials equals 1-(1-p)^n. First order approximation (this is the Binomial approximation), this equals n*p. This is accurate for small p and large n, exactly the situation smoking would be in.
- tarboreus 2y ago
  Seems likely there are cleanup and repair mechanisms in play and outpacing those mechanisms would create a nonlinear threshold effect.
- johnea 2y ago
  Another millennial lost in make believe 8-/ Those are very nice numbers! It's so neat and tidy! It's also a complete divergence from physical reality. You know, that boomer land where old people yell at the cloud? For starters, I'm an advocate of total tobacco abstinence. I watched so many people shrivel up and die from tobacco as I grew up in the south, that I would never ever be a user. Even the people that I know who are still users basically say they would really like to quit, but they're just too addicted. The withdrawal is just too intense and long lasting. One friend's mom quit because of advancing emphysema, she said she craved a cigarette every day for the remaining 10 years of her life. Tobacco has a withdrawal on par with heroin, but you don't even get high from it, you just feel a relief from the withdrawal after using. It's one of the most insidious drugs of compulsion known to man, which is why it's such a commercial success. But if each cigarette takes 20 minutes off of a persons life, I know a few people who should have died in the 1800s. Almost nothing in the natural world is a linear phenomenon.

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irjustin 2y ago

Actually, doesn't it have to be linear? I'm having trouble looking up the exact study, the link they provide doesn't actually link the study. But if I were to structure an observational smoking study, I basically track smokers vs non-smokers from the same population. Hope that my n is big enough and then simply track years non-smokers lived longer vs number cigs smoked. Thus linear. Help me - because I can't imagine a different way to run this.

randomNumber7 2y ago
In medicine is often a threshold effect. Only if you cross some threshold, harm is done. I can not imagine that someone who smokes a few cigarettes in their 20s loses the same per cigarette as someone who smokes for years.
- chithanh 2y ago
  To be more precise: It is not so much a (dose) threshold but how much margin/reserves your body still has. For example kidney injury is progressive, and by the time the kidney's functional reserve is exhausted, things will remain bad until death or kidney transplant. Also for diseases like HIV/AIDS, the cognitive reserve influences how long it takes until HIV associated dementia sets in.
- irjustin 2y ago
  >I can not imagine that someone who smokes a few cigarettes in their 20s loses the same per cigarette as someone who smokes for years. Realistically even in a large enough sample set you won't see a "jump" or "cliff". It'll just look like blurry data. At some point, you'll be like obviously this is making a difference, but it'll be this very wide band and putting drawing a line will never be right. You'll end up saying something like >500-12,000 smoked means X minutes per cig. The band will be so sloppy it's better to just go linear and say an overly simplistic answer.
deleted 2y ago
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isaacfrond 2y ago

I can well imagine a (first order) linear effect. Inhaling toxic fumes gives a probability p that a cell is harmed into a cancer cell. The probability of a hit after n trials equals 1-(1-p)^n. First order approximation (this is the Binomial approximation), this equals n*p. This is accurate for small p and large n, exactly the situation smoking would be in.

tarboreus 2y ago
Seems likely there are cleanup and repair mechanisms in play and outpacing those mechanisms would create a nonlinear threshold effect.
johnea 2y ago
Another millennial lost in make believe 8-/ Those are very nice numbers! It's so neat and tidy! It's also a complete divergence from physical reality. You know, that boomer land where old people yell at the cloud? For starters, I'm an advocate of total tobacco abstinence. I watched so many people shrivel up and die from tobacco as I grew up in the south, that I would never ever be a user. Even the people that I know who are still users basically say they would really like to quit, but they're just too addicted. The withdrawal is just too intense and long lasting. One friend's mom quit because of advancing emphysema, she said she craved a cigarette every day for the remaining 10 years of her life. Tobacco has a withdrawal on par with heroin, but you don't even get high from it, you just feel a relief from the withdrawal after using. It's one of the most insidious drugs of compulsion known to man, which is why it's such a commercial success. But if each cigarette takes 20 minutes off of a persons life, I know a few people who should have died in the 1800s. Almost nothing in the natural world is a linear phenomenon.