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Is cancer as prevalent as it was prehistorically?

  1. Jul 10, 2017 #1
    Almost everyone I've known has had someone close to them have cancer in some form or another. When I was doing some reading on the matter I encountered a statistic saying that one in two Americans will have any form of cancer.

    I really have a hard time understanding why so many people are getting cancer nowadays. By comparison, do you think caveman 'Bob' would have lived with the same chances of contracting cancer as modern day 'Bob'?
     
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  3. Jul 10, 2017 #2
  4. Jul 10, 2017 #3

    russ_watters

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    No, cavemen didn't live anywhere near long enough to get most cancers.
     
  5. Jul 10, 2017 #4
    I agree. Yet, why is cancer still so prevalent nowadays? The epidemiology of the disease isn't exclusive to old age nowadays and is affecting younger and younger age groups.
     
  6. Jul 10, 2017 #5

    russ_watters

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    That's a much more complex question. People get cancer because our genetic code makes mistakes. The reasons those mistakes happen are diverse and complex.
    No, but even if it were evenly distributed (it isn't), you'd still see more than twice as many people with cancer today than in caveman times because of it. But the impact of the fact that cancers are more prevalent in old age (because genetic mistakes pile-up over time) will add several more multipliers.
    I doubt that's true: do you have a source for it?
     
    Last edited: Jul 10, 2017
  7. Jul 10, 2017 #6

    russ_watters

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  8. Jul 10, 2017 #7
    Last edited: Jul 11, 2017
  9. Jul 11, 2017 #8

    davenn

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    interesting article :smile:

    it would be interesting to see the stats on specific cancers and their increases or decreases
    melanoma ( skin) vs bowel vs prostate vs breast for example and see how that varies for age/sex groups

    going to have to do some searching

    I know so many people personally that have got / been through / died from cancer :frown:

    I lost my best man for my first marriage on the 1st anniv -- dead within a year of diagnosis, they couldn't stop it -- 42 yrs old
    my mum had a cancerous kidney removed, she survived -- late 60's at time
    my next door neighbour is in 5 yr battle with bowel cancer -- mid 60's

    on and on and on :frown:


    a lot of the "increased prevalence" comes with the increased and better screening techniques

    akin to people saying that there seems to be more earthquakes these days
    the numbers of various sizes of quakes hasn't changed, what has is the much better and more widely distributed seismic detection network and the more active media reporting of events

    that's definitely some of the problem but doesn't cover all specific cancers ... skin, breast and bowel for example
    As the article says ... life styles and natural exposure play a part that is totally unrelated to genetic breakdown assoc. with old age.

    Environment ... more, unprotected sun-tanning (ozone depletion related) carcinogenic chemicals in the air, water etc
    that our ancestors were not subject to, even if your went back only a few 100 years ( I suspect they were more likely to dies from various plagues than cancer )

    Man is producing carcinogenic chemicals over the last 100 years that were never even heard of 100++ years ago
    http://www.unc.edu/courses/2005spring/envr/132/001/Carcinogenesis.pdf


    just a few thoughts :smile:


    Dave
     
  10. Jul 11, 2017 #9

    russ_watters

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    Yes, though hopefully the OP is aware that the ancients didn't have cancer screening techniques, so that should be an obvious difficulty in figuring how often they got cancer. I don't think it is possible to really know and at best we would have to assume demographically corrected rates are the same. Demographics alone tell us whereas somewhere around 1 out of 2 get cancer today, for the ancients it was more like 1 in 20(detected or not) - just because they only lived half as long.
    I meant to word that a bit more generally; it is not just internal mistakes, but externally caused genetic damage also accumulates.
    While that is obviously true, I would caution against falling victim to the "naturalistic fallacy"(natural = better) that probably is either the cause or effect (or both) of the thinking in the OP.

    Difficulty normalizing screening accuracy aside, the link I posted included a graph showing the drop in lung cancer rates (in the UK) recently due to the drop in smoking rates. So clearly, human-caused carcinogens matter. But the ancients smoked too. How much, I don't know. The second leading cause of lung cancer, at least in the USA, is radon. Presumably an ancient who lived in a tent wouldn't be subject to it, but an ancient who lived in a cave might have had worse exposure.

    Other factors that may have increased cancer rates in ancients:
    --Increased sun exposure
    --Poorer hygeine
    --Poorer sanitation
    --Poorer food quality and preservation

    Though admittedly, I'm not sure how much of those last three were cancer causing and how much they just made people sick in other ways. But a quick google tells me that salt meat preservation (common before refrigeration), for example, may cause cancer.
    [edit]
    Interesting link. Page 3 shows charts of death rates (age adjusted), and I'm going to assume that prior to about 1950 we had essentially no treatment options for cancer (other than perhaps removing tumors), so the substantial drops in death rates for uterine and scomach cancers are likely due primarily due to other advances in medicine and standard of living. E.G., I'm speculating that it is the invention/proliferation of refrigeration that caused stomach cancers to drop by 2/3 from 1930 to 1960 (half for men, 80% for women).
     
    Last edited: Jul 11, 2017
  11. Jul 11, 2017 #10
  12. Jul 11, 2017 #11

    Vanadium 50

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    How much should we spend? And do you know how much we are spending now?

    I remember a discussion with a woman who argued that the Federal R&D budget be slashed to 10% of the total. It's actually about 3-1/2%.
     
  13. Jul 11, 2017 #12

    russ_watters

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    More than what? We spend a vast amount of money on cancer research (public and private), but squeaky wheels get greased, so you can probably guess which one(s) get the most funding. It isn't necessarily aligned with the biggest incidence/death rates.

    And though people say we can't "cure" cancer, really we can -- and do it vastly better than even 20 or 30 years ago. We're getting a substantial tangable benefit for that substantial investment.
     
  14. Jul 11, 2017 #13
    More and I guess not enough (or we are all just betting by the time we get the call, medicine will have advanced enough to feel ok about it)

    And by "we", I mean as individuals. Personal donations. However, I suppose it does matter at what age I get the call. If at 50, well yeah, I would like medicine to save me. If at 85, maybe it's time to go anyway and I could have used the money in other ways.
     
  15. Jul 11, 2017 #14

    russ_watters

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    Not to derail the thread, but that attitude is growing and will become essential to ensuring healthcare spending doesn't bankrupt us in the near future. Needless to say, I agree.
     
  16. Jul 11, 2017 #15

    jim mcnamara

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  17. Jul 11, 2017 #16

    russ_watters

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    Me no likey:
    I'm going to have to look into this more, but this strikes me as claims not in evidence and naturalistic fallacy.
     
  18. Jul 11, 2017 #17

    jim mcnamara

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    @russ_watters - I picked it for the picture. @Ygggdrasil has strong points to make on the subject.

    I've seen papers with the environment's role in carcinogenesis given varying percents over time, all were non-zero. So I don't see that as a conflicting statement.
    Possibly overstated. Remember this is a science reporter writing the story, and you know how that goes.
     
  19. Jul 11, 2017 #18

    Ygggdrasil

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    The extent to which cancer can be prevented is an important and sometimes contentious issue. Probably the most widely cited estimate on the issue comes from Cancer Research UK, which estimates that 40% of cancer cases are preventable by changes in lifestyle (such as quitting smoking, maintaining a healthy bodyweight, and vaccinating against viruses that cause cancer like HPV and hepatitis). Estimates in the scientific literature vary; while some have estimated that as much as two-thirds of cancer are due to "bad luck" and unavoidable, others find that up to ~90% of cancers are due to environmental factors. Overall, there is agreement that many cancers are due to elements of modern life (e.g. obesity) and some are unavoidable byproducts of human aging, but the exact numbers attributable to each are still a subject of debate. See these previous threads on physics forums for more discussion on the topic:
    https://www.physicsforums.com/threads/bad-luck-is-primary-cause-of-most-cancer.790125/
    https://www.physicsforums.com/insights/causes-cancer-bad-luck-bad-lifestyles/
    https://www.physicsforums.com/threads/cancer-causes-circa-67-are-replication-error.908823/
     
  20. Jul 11, 2017 #19
    Sorry to go all nutty, but, isn't plastic a type of carcinogenic substance? I don't think drinking water contained in plastic exposed to high heat is a great idea.
     
  21. Jul 11, 2017 #20

    Ygggdrasil

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    From Cancer Research UK:
    http://www.cancerresearchuk.org/abo...-controversies/plastic-bottles-and-cling-film
     
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