
Rise in cancers 'caused by weight' - onuralp
http://www.bbc.com/news/health-43502144
======
jere
>Rise in cancers 'caused by weight'

>The charity also found that excess weight now caused 6.3% of all cancer cases
- up from 5.5% in 2011

>Prof Mel Greaves, a cancer biologist at the Institute of Cancer Research, in
London, said the study was an "endorsement" of the idea that many cancers were
potentially preventable. But he said the idea that obesity itself or eating
too little fibre "causes" cancer was "somewhat simplistic" and still needed to
be explored further.

What a rollercoaster.

~~~
RobertRoberts
> _What a rollercoaster._

Decades ago everyone _knew_ smoking caused cigarettes. As a middle schooler I
could intuitively see that overeating sugar would lead to diabetic issues that
are just now being "proven" by science.

Is it possible that the UK health system has figured out something that is
obvious through their experiences with so many people? If you are overweight
and unhealthy in general, that in general you will have more instances of
every disease?

But until there are actual concerted scientific studies, not intimidated by
social/political bullying, to consider behavior as a risk factor for disease,
what can be done?

We can only rely on common sense, simplistic views, spreadsheets of private
data we aren't legally allowed to share, etc... People in health care are
stuck between a rock and a hard-place. (scientific studies vs what is obvious
in front of them)

~~~
lebrad
>Decades ago everyone _knew_ smoking caused cigarettes.

Surrealists, dadaists and fans of retrocausality tried in vain to warn us that
smoking caused cigarettes

~~~
dragonwriter
> Surrealists, dadaists and fans of retrocausality tried in vain to warn us
> that smoking caused cigarettes

At risk of taking this typo-launched tangent far too seriously, smoking
absolutely caused cigarettes, and without retrocausality; cigarettes weren't
the first vehicle for smoking, and were developed as a result of the
popularity of the practice.

------
spodek
> Across the UK, smoking remained by far the leading cause of preventable
> cancer, although it dropped from 19.4% in 2011 to 15.1%. Second was being
> overweight or obese . . .

Since obesity doesn't just randomly happen but has causes, shouldn't they say
"caused by" the causes of obesity -- i.e. sugar, inactivity, etc?

~~~
klmr
It’s not that simple. As the article correctly states:

> But he said the idea that obesity itself or eating too little fibre "causes"
> cancer was "somewhat simplistic" and still needed to be explored further.

Diet is certainly contributing to cancer risk but there’s no simple, direct
line from sugar to cancer, or from inactivity to cancer.

For example, one aspect of cancer risk is that it’s simply a game of numbers:
obese people have bigger cells (and, at least in the case of children, _more
cells_!). More cells trivially translates into a higher cancer risk because
every single cell individually has the potential of becoming a tumour
precursor. But even a constant number of bigger cells increases cancer risk by
a similar logic: more cellular mass increases the risk of a cell becoming
cancerous because there are more molecules that can become abnormal, disrupt
cellular processes and ultimately lead to DNA damage.

These are the facts. Whether this noticeably contributes to the increased
cancer risk in obese people is an open question. Nevertheless, in this
scenario it’s actually the obesity itself, and _not_ the diet/inactivity that
acts as a causal factor for cancer.

Ultimately this is probably a tiny contributor. Another comment correctly
singles out that obesity causes (chronic) inflammation, which is almost
certainly a much bigger single contributor to cancer risk.

~~~
jiggunjer
By that overly simplistic statistical reasoning, whales should be riddled with
tumors.

~~~
nonbel
The parent is wrong in that they fail to distinguish between
terminal/differentiated cells and tissue stem cells. Also they imply there is
a one-to-one correspondence between the relevant cell divisions and number of
total cells at any one time. This is not the case.

Eg, you can have one skin stem cell divide once to replace a single terminal
cell (one of the daughters remains as a stem cell). Or that one daughter cell
can divide itself once to replace two terminal cells per stem cell divisions.
Or those _two_ cells can each divide to get 4 terminal cells per stem cell
division, etc.

The relevant number is divisions since the fertilized egg for each stem cell
lineage.

~~~
klmr
> they fail to distinguish between terminal/differentiated cells and tissue
> stem cells

I don’t distinguish them because what I’ve said is true both for
differentiated and stem cells. I’m not saying that there are no relevant
differences between these cells, obviously.

> they imply there is a one-to-one correspondence between the relevant cell
> divisions and number of total cells at any one time

Uh, where did I imply that? That would obviously be false but, again, it’s not
relevant to the argument I’m making.

> The relevant number is divisions since the fertilized egg for each stem cell
> lineage.

The relevant number _for what_? I was talking about the total number/size of
cells at a given time, not the number of cell divisions, which is an entirely
different (but also relevant) facet of tumourigenesis.

------
AstralStorm
Percentages are no good without NNTs. It does not mention that some cases are
much harder to treat than others.

(NNT = number or treatments needed to treat or prevent one case of cancer)

------
ec109685
What is the mechanism to correlate an incidence of cancer with being over
weight versus another risk factor?

~~~
AstralStorm
Likely generalized inflammation. It is also not unlikely that overweight
people eat less nutritious diet in terms of phyto- and micronutrients some of
which may prevent cancer. Fat cell proliferation uses some of the same
mechanisms as certain cancers too.

~~~
atupis
Also overweight people have more cells than thin people. So there is bigger
risk to malicious cell mutations. Taller people have same problem
[https://www.theguardian.com/society/2015/oct/01/taller-
peopl...](https://www.theguardian.com/society/2015/oct/01/taller-people-more-
likely-to-get-cancer-say-researchers)

~~~
nonbel
Yes.

The current thought is that cancer arises by tissue stem cells accumulating
mutations at a low rate until it goes out of control. Every division there is
some chance of error. If you have more divisions, there is a higher chance of
cancer.

If you always keep this in mind: cell division -> cancer, so much will make
sense. Anything requiring an increase in cell division will increase the
chances of cancer in that tissue (smoking damages lung cells which need to be
replaced, uv damages skin cells, being larger means you have more cells).

That is not to say that immune surveillance for clearing these bad cells plays
no role, or that DNA damage sensitivity/repair can't be increased/decreased,
or that those rates need be similar in different species. However, the main
idea behind the entire modern cancer research programme is that cell division
-> cancer.

More info:
[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC54830/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC54830/)

~~~
rsync
"If you always keep this in mind: cell division -> cancer, so much will make
sense."

I am not so sure this is a good heuristic.

An athlete, or even a moderately active (fit) person is inducing quite a bit
of cell division due to the teardown and regrowth of muscle and bone, etc.,
caused by exercise.

However, activity and exercise seem to be (strongly) negatively correlated
with cancer.

Instead, I think a better mental model is the winnowing of a population. When
you subject your (muscles/bones/heart/lungs) to a highly stressful exertion,
some of the cells just can't maintain that output _and so they are killed off,
or commit suicide by the process of apoptosis_.

But if you never subject your cell population to an apoptosis-inducing level
of stress, you're just cultivating an increasingly weak population of cells.

I highly recommend the book by Nick Lane titled: Power, Sex, Suicide which
explores these topics...

[https://en.wikipedia.org/wiki/Power,_Sex,_Suicide](https://en.wikipedia.org/wiki/Power,_Sex,_Suicide)

------
agumonkey
Good, less calories means less livestock means less transport and pollution.
Virtuous cycle.

------
jlebrech
Funnily enough, lack of exercise, alcohol, meat can cause obesity. and not
eating enough veg gives people fibre deficiency.

Also to note none of those causes of cancers are protein deficiency.

~~~
n0tme
Bottom line: I am so fucked

------
stefap2
At the time, she was nearly 20 stone.

20 stone = 127 kg = 280 lbs

------
wyclif
_and third was exposure to the Sun_

That capitalised "Sun" will no doubt unintentionally amuse UK readers of the
news...

~~~
cup-of-tea
Why? Sun is a proper noun. The newspaper would be "The Sun" (capital T).

~~~
croon
It can be, but that's not usually how it's used.

You're playing in the sun, not "the Sun".

Earth's yellow sun, not Earth's yellow "Sun".

It's both common and proper, depending on context.

~~~
cup-of-tea
Yes, but I would have written it as a proper noun as it was written there.
They could have instead said "exposure to sun". But if you add the definite
article, it's a proper noun.

~~~
croon
> But if you add the definite article, it's a proper noun.

Not in my example.

Do you regularly go take walks in the Sun?

~~~
cup-of-tea
Well, quite, but in the BBC article it could have been either IMO.

