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Cue 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. [0] https://www.nature.com/articles/nrneph.2017.5
Earlier quoted context omitted.
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.
https://doi.org/10.1371/journal.pgen.1007108
"Recent single-cell studies point to the possibility that essentially all cells have unshared mutations in their genomes. In view of this extensive genetic diversity, it is perhaps not surprising that mutations that confer a proliferative advantage are readily detected as clonal populations of increasing abundance and size in the elderly. These clonal populations might lead to loss of organismal health through the functional decline of tissue and/or the promotion of disease processes, such as cancer. In this review, we summarize recent research that supports the notion that aberrant clonal expansion (ACE) resulting from cancer-associated mutations are common in noncancerous tissue and accumulate with age. We propose ACE to be a previously underappreciated aging phenotype that is universal in most organisms, affects multiple tissues, and likely helps explain why aging is the biggest risk factor for cancer."
If 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.
There's a huge variability in terms of your thymus (the organ that produces new T cells) getting switched off after your mid 20s. For some people its almost immediate. For others, it takes many decades: https://insight.jci.org/articles/view/93739/figure/5
Tweaking this process, without breaking anything else, would be huge to extend our lifespan with some good quality years.
One 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…
Earlier quoted context omitted.
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.
Possibly so, which is a phenomenon that might explain how stochastic nuclear mutation at its given rates can possibly cause widespread enough harm to be significant. There is an interesting recent paper on that subject: https://doi.org/10.1371/journal.pgen.1007108 "Recent single-cell studies point to the possibility that essentially all cells have unshared mutations in their genomes. In view of this extensive genetic…
Really? I figured as we age our cancer rates will plummet while our immune systems only strengthen, which is why the leading cause of the death in the elderly is extreme sports.
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?
I 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...
An even stronger data point to me would be the actual people of Okinawa who are (were?) among the healthiest and oldest in the world.
In addition to having a high quality diet and a rich social life in general, they are practicing “hara hachi bu” – the confucian tradition of always eating only until “about 80% full”.
If 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.
I would wager the opposite is true. Body systems maintain themselves and their fitness and function through use.
The obvious examples are bone and muscle tissue that become stronger through stress but are you aware that breast cancer incidence is strongly, negatively correlated to frequency and duration of breastfeeding ?
The immune system is also a bodily system and I would be surprised if it did not, also, strengthen itself and maintain its function through stresses and use.
"For example, curing the common cold and/or developing a universal flu vaccine."
Be careful what you wish for ...
We "cured" hard physical labor and traditional life patterns with lots of walking and standing. How's that working out for us ?