How do you account for the observation that incidence of cancer in young, immunosupressed individuals (e.g. solid organ transplant recipients), whilst increased, is no way comparable to that seen in elderly individuals?
As we age, cancer rates go up as immune system winds down
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Re: As we age, cancer rates go up as immune system winds down
#12If the immune system has finite resources, would reducing the lifetime drain on those resources by infectious diseases delay the age at which we can expect get cancer? For example, curing the common cold and/or developing a universal flu vaccine.
Via mechanisms similar to either the hygiene hypothesis or hormesis, it's possible those might backfire. This is highly speculative, but:
* the hygiene hypothesis suggests that allergies and auto-immune disorders can arise from having insufficient immune-system challenges, especially when young. Lacking the calibration from an 'expected' or 'optimal' level of dirt/allergens/infectious-diseases, the immune system starts doing unwanted self-destructive things.
* hormesis is the observation that almost everything bad for you also turns out to be good in very-tiny exposures – radiation, poisons, cancer-causing chemicals, etc. It's as if tiny doses trigger beneficial self-repairs to occur even beyond the direct damage received, even as larger doses overwhelm that mechanism.
Removing mild, survivable challenges from the environment could thus leave the immune system less 'tuned' for the full spectrum of challenges it faces (like clearing early cancers). It's an adaptive dynamic system with nonlinear effects, not a simple pool of fixed exhaustible capability.
Re: As we age, cancer rates go up as immune system winds down
#13I always think of these two monkeys[i] when I consider slowing down my age. [i] http://www.slate.com/articles/health_and_science/medical_exa...
This is really great! Thanks for the link. I think you should post it to HN
Re: As we age, cancer rates go up as immune system winds down
#14If the immune system has finite resources, would reducing the lifetime drain on those resources by infectious diseases delay the age at which we can expect get cancer? For example, curing the common cold and/or developing a universal flu vaccine.
Some types of cancer are directly caused by infectious diseases. The HPV vaccine has greatly reduced cancer rates.
Moral of this story, figure out how to tell all the anti-vaccination people they are wrong in some way they will believe. (the first is easy, the latter is impossible in my experience)
Re: As we age, cancer rates go up as immune system winds down
#15If the immune system has finite resources, would reducing the lifetime drain on those resources by infectious diseases delay the age at which we can expect get cancer? For example, curing the common cold and/or developing a universal flu vaccine.
Mice raised in a germ-free environment have improved health measures and longer average life span:
http://dx.doi.org/10.1016/j.chom.2017.03.002
Not all pathogens are equal; cytomegalovirus may be far more important than the rest:
https://doi.org/10.3389/fimmu.2017.01953
And historically, reducing the burden of infectious disease already has increased life expectancy and reduced/postponed incidence of age-related disease:
http://www.slate.com/articles/health_and_science/science_of_...
Re: As we age, cancer rates go up as immune system winds down
#16How do you account for the observation that incidence of cancer in young, immunosupressed individuals (e.g. solid organ transplant recipients), whilst increased, is no way comparable to that seen in elderly individuals?
Other age-related cell and tissue damage that raises the risk of cells becoming cancerous, or reduces the effectiveness of internal-to-the-cell controls that can shut down and destroy cancerous cells, would be the other variable, I'd imagine.
Re: As we age, cancer rates go up as immune system winds down
#17One immediate problem with the hypothesis that cancer is caused by the loss of T cells with age is the fact that HIV also destroys T cells, and it is associated with increased risk of some types of cancer. But the cancers associated with HIV are different from those associated with aging. In particular, Kaposi sarcoma occurs 500 times more in HIV patients than the general population. So there must be something else g…
Agree. No doubt immunosenescence contributes to the increased rate of malignancy at older ages but the spectrum of cancers seen in immunosupressed individuals does not that match seen in the elderly.
Re: As we age, cancer rates go up as immune system winds down
#18Cue the senescence guys who aim to fix accumulated damages there.
Ultimately, I think it comes down to metabolism. As you age, your metabolism slows. Coenzymes like NAD+[0] are depleted.
Re: As we age, cancer rates go up as immune system winds down
#19How do you account for the observation that incidence of cancer in young, immunosupressed individuals (e.g. solid organ transplant recipients), whilst increased, is no way comparable to that seen in elderly individuals?
Other age-related cell and tissue damage that raises the risk of cells becoming cancerous, or reduces the effectiveness of internal-to-the-cell controls that can shut down and destroy cancerous cells, would be the other variable, I'd imagine.
I think far more likely that the predominant variable is the expansion of mutant clones over time to occupy large fractions of the stem cell reservoir.
Re: As we age, cancer rates go up as immune system winds down
#20Cue the senescence guys who aim to fix accumulated damages there.
I mean, it bears repeating on account of the fact that senolytic treatments make a lot of other health problems seem like not even worth understanding