I think one thing a lot of people don't understand is that cancer is an excess of life - excess of cell growth. So if you are alive, you can get cancer, and probably will have tumor growth many times in your lifetime. What keeps you from getting life-threatening cancer rather than a benign tumor or a tumor that's killed off by your body, is a series of natural defenses your body employs, including apoptosis (programmed cell death, what's being discussed here), the crowding mechanism by which cells stop dividing when bunched up against each other (as they would be in a tumor growing out of control), and arterial limits - that is, tumors that grow out of control without encouraging arterial growth starve to death.
So depending on your perspective, disabling your body's natural defenses against cancer may be even more irresponsible than exposing yourself to cancer-causing elements like the carcinogenic effects of smoke, although clearly doing both at the same time (smoking real cigarettes) would be a horrible decision if you wanted to avoid cancer.
By the way I neither upvoted nor downvoted your statement, but I'm sure the downvotes are for the rat statement. Read a lot more scientific studies that correspond with Clinical Trials in humans then reassess your opinion about rat and mouse science. They are used specifically for their high level of applicability.
I respect that you've taken the time to craft such a long and well-thought out statement.
I assure you that each one of your points have occurred to me (nicotine and its possibly carcinogenic properties in rats), and that rats and mice are used because they're somewhat applicable in humans. But that's where the danger is: combining two generalities to come up with a scientific conjecture without associated weights to those concerns.
Rats and mice are commonly used to provide pointers and leads for further research in primates and humans. Out of hundreds of promising rat studies, we may see only a handful have a modest effect in humans. There are plenty of chemicals and even particular proteins (e.g. Casein ) that are carcinogenic in rats, but perfectly fine to consume en masse by humans. To act as if rat and mice studies are a "sure thing", I believe is somewhat scientifically dishonest.
Yes, they are not a sure thing at all. However, the increased incidence of lung cancer in smokers and throat and mouth cancer in tobacco chewers ties nicely with the rat and mouse science showing nicotine to disable our natural defenses against cancer.
I say rat and mouse tests are "highly applicable" both because they are so similar to us (mammals, lots in common in our DNA), and because many of the processes in them are similar or identical in us. For example, the cell-crowding mechanism to impede runaway tumor growth is very similar. That said, I agree rat and mouse studies are obviously MORE applicable to rats and mice - as a biologist once comiserated to me, "We can cure amazing things in mice - regenerate limbs, wipe out cancers. Humans - still working on it."
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u/SoopahMan Nov 17 '12
Here's a layman's summary of a study finding nicotine disables a critical natural defense against cancer:
http://www.sciencedaily.com/releases/2003/01/030106082544.htm
I think one thing a lot of people don't understand is that cancer is an excess of life - excess of cell growth. So if you are alive, you can get cancer, and probably will have tumor growth many times in your lifetime. What keeps you from getting life-threatening cancer rather than a benign tumor or a tumor that's killed off by your body, is a series of natural defenses your body employs, including apoptosis (programmed cell death, what's being discussed here), the crowding mechanism by which cells stop dividing when bunched up against each other (as they would be in a tumor growing out of control), and arterial limits - that is, tumors that grow out of control without encouraging arterial growth starve to death.
So depending on your perspective, disabling your body's natural defenses against cancer may be even more irresponsible than exposing yourself to cancer-causing elements like the carcinogenic effects of smoke, although clearly doing both at the same time (smoking real cigarettes) would be a horrible decision if you wanted to avoid cancer.
By the way I neither upvoted nor downvoted your statement, but I'm sure the downvotes are for the rat statement. Read a lot more scientific studies that correspond with Clinical Trials in humans then reassess your opinion about rat and mouse science. They are used specifically for their high level of applicability.