Obesity/Insulin and Cancer

July 20, 2020

Information

July 19, 2020

Yale Cancer Center

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00:14Welcome to Yale Cancer
00:15Answers with your host
00:17Doctor Anees Chagpar.
00:18Yale Cancer Answers features
00:20the latest information on cancer
00:22care by welcoming oncologists and
00:24specialists who are on the forefront
00:26of the battle to fight cancer.
00:28This week is a conversation about
00:30the role of obesity and insulin in
00:32cancer with doctor Rachel Perry.
00:34Doctor Perry is an assistant professor
00:36in Medicine and Endocrinology
00:38and cellular and Molecular Physiology
00:40at the Yale School of Medicine,
00:42where doctor Chagpar is a
00:45professor of surgical oncology.
00:47Rachel,
00:47maybe we can start by talking
00:49a little bit about obesity.
00:55They talk about it
00:57being like the other pandemic.
00:59It's really something that's
01:01prevalent across the world,
01:02is that right?
01:05Yes, that is absolutely true.
01:06So at this point we're coming up on close
01:10to 50% of Americans who are obese and
01:13large numbers really worldwide as well.
01:15And with that obesity is a problem
01:18in and of itself, it increases
01:21the risk of cardiovascular disease,
01:23stroke and cancer which we will discuss
01:24today and other conditions,
01:26but it also brings with it an
01:28increased risk of type 2 diabetes
01:36which can be caused by obesity and
01:39is expected to effect 100% of
01:41Americans, or would affect 100%
01:42of Americans if current trends
01:44continue by the year 2050.
01:46That really is mazing.
01:49So that tells us we need to do
01:51something to intervene here.
01:53Two statistics that
01:54you put out in a single sentence
01:57that just completely blew me away.
01:59The first is that almost half of all
02:02Americans are obese and all of us are
02:05going to end up with Type 2 diabetes
02:08in 30 short years,
02:10that's incredible.
02:11I just have to correct myself.
02:14Overweight or obese, almost 50%.
02:16I was gonna ask about that.
02:19So what really is the definition of obesity?
02:22I mean are we talking about
02:25that last five or 10
02:28pounds that everyone has to lose?
02:31Or are we talking about people
02:33who are seriously several pounds
02:35or several 100 pounds overweight?
02:37Somewhere in between the two.
02:40Technically, obesity is defined
02:42as a body mass index over 30,
02:44and that really corresponds to
02:46being about 30 to 50 pounds,
02:48closer to 50 pounds over
02:49our ideal body weight,
02:51and so we're not talking about,
02:53you know the last five or
02:5510 pounds from high school.
02:56That may put us into the overweight category,
02:59but we don't need to be hundreds of pounds
03:02overweight to be in that obese category.
03:05That can really increase our risk
03:06of a number of health conditions,
03:09and so one of those conditions is cancer.
03:12Can you give us a metric?
03:15How much does obesity really
03:17increase your risk? I know a
03:19lot of people worry about cancer,
03:21I mean certainly they worry
03:23about diabetes and heart disease,
03:25all of those are some of the
03:28key killers of Americans these days.
03:30But how much does obesity
03:32really impact cancer?
03:33And does it affect all kinds of
03:36cancer or just a select few?
03:38Well, those are
03:39both great questions and in the
03:41answer to the first question,
03:43how much does obesity affect cancer risk,
03:45it's difficult to answer because it
03:48really depends on the tumor type
03:50and so I'm going to answer your
03:52second question first and that is
03:57at this point there are 13 tumor types
03:59that the Centers for Disease Control have
04:02associated with obesity and that means,
04:05with obesity increasing the risk and
04:07causing a worse prognosis of those tumor
04:09types and those include breast cancer,
04:11ovarian, uterine, renal,
04:12pancreatic, thyroid, colorectal,
04:13as well as several others.
04:16And but there are few tumor types
04:18where there's no risk of obesity,
04:20and we really don't understand what causes
04:23some tumor types to be worse with obesity,
04:26and other tumor types not to be
04:28worse within the tumor types that
04:31are associated with obesity,
04:32there are some where obesity brings with it
04:35a relatively lower risk in breast cancer.
04:37I believe the increase is about
04:4020 to 30% of an increased risk
04:42with obesity, still very significant
04:44but smaller than others.
04:46Whereas with pancreatic cancer,
04:47risk is a couple fold, ovarian cancer as well,
04:50a couple fold greater risk with obesity.
04:53So as I said
04:55it really depends on the tumor type.
04:57But because these 13 cancer types that
05:00are associated with obesity are among
05:02the most prevalent cancer types out there,
05:04it really translates to a
05:06significant excess risk.
05:07From an epidemiological standpoint
05:09that comes
05:10with obesity.
05:11And we really don't know why.
05:14Even 20 to 30% increased risk of breast
05:17cancer seems pretty significant to me.
05:19But why is that 20 to 30%
05:22but in ovarian cancer we're
05:24talking about more like 200%?
05:26Do we know why that is?
05:29Why it is that obesity effects more
05:31cancers in some situations than in others?
05:34We really don't,
05:36and that is a tremendous open question
05:38that we need to figure out.
05:41Because if we could figure out
05:43why obesity worsens certain
05:45cancer risks worse than others,
05:47then perhaps we would have a better handle
05:50on why obesity increases cancer risk
05:52at all, and that would be the
05:55target that would be where we
05:57can intervene in this process.
05:59A lot of labs, mine included as well as
06:02many others are working on this
06:04question to try to uncover number one,
06:07why are certain tumor types affected
06:09and not others and #2 why are
06:11certain tumor types affected worse than
06:14others because there's really going
06:16to be a major epidemiological role for
06:18uncovering that information.
06:21Do we know what exactly or how exactly
06:24obesity increases your risk of cancer?
06:29We're still working on that and there
06:31have been a number of potential mediators
06:33that people have thrown out there.
06:36One that my lab studies is
06:38insulin and related to that,
06:40insulin-like growth factor one.
06:41The concentrations of these molecules
06:43increase with obesity and we and others
06:46have shown that in vitro those molecules
06:48can increase tumor cell division.
06:50We can talk a little bit later about
06:53the mechanism by which that may occur,
06:55if you'd like.
06:56But there have been a number of other
06:59factors that people have proposed as well,
07:02including inflammatory cytokines.
07:03Obesity is a pro inflammatory
07:05state and so inflammatory cytokines
07:07are up in obese individuals.
07:08There's leptin, a protein that is
07:11secreted by the fat and has been shown in
07:14certain models to accelerate tumor growth.
07:17There are other hormones that
07:19may be involved, we
07:21mentioned insulin,
07:22but also potentially Glucagon,
07:24Adiponectin.
07:25And any and all of these have
07:28been shown in vitro,
07:29so in cell culture studies,
07:31to accelerate tumor growth,
07:32and there's been increasing
07:34work in mice in humans,
07:35it's a little bit more difficult
07:37to tell the answer because you know
07:39a patient comes in with cancer.
07:41you can't do all these types of
07:44interventions that we're able to
07:45do in the lab to really be able to
07:48pick out certain positive factors,
07:50but all of these hormones and cytokines
07:52that I just listed correlate with
07:54tumor appearance and progression.
07:58And a point
07:58I wanted to make related to the
08:01role of obesity,
08:02we talked about how obesity may increase
08:04the risk of certain types of cancers,
08:07but it also worsens the progression
08:09and increases the rate of recurrence
08:11of the cancer.
08:12So when we say that obesity may increase
08:15the risk of breast cancer by 20%,
08:18it also worsens the prognosis of
08:20someone who's already diagnosed with
08:22breast cancer as well as increasing
08:24her risk of recurrence, so that 20%
08:26increased risk is really not just 20%.
08:29Because the increased risk continues
08:31down the line and we really need
08:34to figure out what the reason for
08:37that is so that we can intervene in
08:39a mechanistically driven manner.
08:41And I think that the
08:44other problem now that you mention
08:46it, is the fact that obesity really
08:48increases the risk of recurrence,
08:50particularly in breast cancer and
08:52maybe in other cancers as well.
08:54Some of the therapies that we use
08:57actually make you gain weight, so
08:59many breast cancer survivors actually
09:02gain weight during therapy and then on
09:05top of that that weight gain or that
09:07obesity increases their risk of recurrence.
09:10So have people looked at that?
09:14I mean, is the weight that you gain
09:16during therapy versus simply just
09:18being overweight to begin with?
09:20Does that make a difference
09:22to your recurrence?
09:23If you were normal weight,
09:25for example, when you were diagnosed and
09:28then you gained weight with your treatment,
09:30does that increase your risk of
09:33recurrence because that weight gain
09:35was related to your treatment versus
09:37if you were overweight to begin with?
09:40In fact it does.
09:42So people have looked at this specifically,
09:44the change of weight during
09:46the course of treatment and those
09:48who gain weight during treatment.
09:49Actually specifically for
09:50breast cancer as you mentioned,
09:52are in fact at a higher risk
09:54of recurrence of their cancer,
09:56and so that's something that absolutely
09:58needs to be kept in mind during therapy.
10:00Now that said,
10:01it's not as simple as it may appear,
10:04because those who lose weight
10:05during treatment
10:07also have a poorer prognosis.
10:08This gets into the issue of cancer cachexia.
10:11So when patients are
10:12being treated for cancer,
10:13have cancer and they lose a
10:15significant amount of weight,
10:17a very large amount of weight so
10:19that they lose a lot of fat and
10:21start to lose muscle as well,
10:23those patients are also at
10:25higher risk for poorer outcomes,
10:26and so we can't simply tell people,
10:28just go and lose weight,
10:30and that's really why we need to
10:32understand mechanistically what this
10:33link is between obesity and cancer,
10:35so that instead of telling people,
10:37oh, just go and lose weight,
10:39we can give them a mechanistically
10:41driven intervention
10:41that may help mitigate that risk of obesity,
10:44while not predisposing them
10:46to cancer cachexia.
10:47So let's unpack that a little bit more.
10:50What do you mean by a mechanistically
10:53driven intervention?
10:56We want to understand what the molecule is or
10:58molecules are that are responsible for
11:00this link between obesity and cancer.
11:03For instance, if the link is
11:05at least in part insulin,
11:07one of my favorite hypothesis,
11:09there are ways that we can lower insulin
11:12while not forcing a patient to lose weight.
11:15There are different drugs that work
11:18in different ways that would all lower
11:21circulating insulin and that would
11:23not require the patient to go on a
11:25restrictive diet or put themselves
11:27at risk for cancer cachexia syndrome.
11:30Similarly, if the link were
11:32certain inflammatory cytokine,
11:33there are various antibodies that
11:34are being developed to block certain
11:37inflammatory cytokine action,
11:38and so we could potentially give
11:40folks an antibody to that particular
11:43cytokine that might lower their risk,
11:45while again,
11:46not requiring them to lose weight.
11:48So it would just allow us to more safely
11:52intervene in this link between
11:54obesity and cancer
11:55if we could understand
11:56exactly what mediates it.
11:58Except that they'd still be at
12:00increased risk of heart disease
12:02and diabetes if they were
12:04overweight, right?
12:05Yes, certainly weight loss
12:06within a healthy range,
12:08so not becoming underweight but
12:10weight loss within a healthy
12:12range is probably going to be the
12:15best way to mitigate this risk.
12:17Overall though it may be very
12:19difficult during cancer treatment,
12:21as you mentioned.
12:22Cancer treatment tends to
12:23cause people to gain weight,
12:25and so during that short period of
12:27time it may be better to focus on
12:30what we can do from
12:32a cancer standpoint,
12:33to mechanistically intervene in this
12:35link between obesity and cancer,
12:36rather than focusing on weight loss.
12:38But long term from a population standpoint,
12:41absolutely we should all be encouraging
12:43our patients and ourselves to
12:45maintain a healthy weight.
12:47Rachel, I want to dig a little bit deeper into
12:50what your lab is doing in terms of
12:52insulin and its link to obesity.
12:55One of the statistics that you
12:57gave us at the top of the show,
13:00which was the link between
13:02obesity and diabetes,
13:03was just mind blowing to me.
13:05So talk a little bit about that
13:08and how insulin plays into that,
13:10as well as into this
13:12whole concept of obesity.
13:14Yeah, so my training was
13:16in straight metabolism.
13:18I studied diabetes and substrate
13:20metabolism during my graduate work
13:22and my post doc and we developed
13:24methods to be able to assess
13:26metabolism in different tissues and
13:28different settings and so one of
13:30the hormones that we focus on in
13:33the metabolism world is insulin.
13:35Insulin is secreted by the endocrine
13:37pancreas when we eat a meal.
13:40When blood sugar levels go up,
13:42insulin is secreted.
13:43Insulin helps ourselves to take up
13:45glucose or sugar so that the sugar
13:48is taken out of the bloodstream
13:50and into the tissues.
13:52And when we do that,
13:54the tissues or even tumors in
13:56certain cases can use that sugar as
13:58fuel for themselves while lowering
14:00blood glucose concentrations.
14:02So in diabetes,
14:03that process doesn't happen efficiently.
14:05People tend to become insulin resistant,
14:08so their bodies don't respond as well
14:10as they need to insulin and so it
14:14either needs to be given by injection,
14:17or certain interventions need to
14:18take place to allow the body to
14:21respond better to insulin and
14:22the work that we've been doing
14:24in my lab in the last
14:27several years has been specifically
14:28looking at this link between insulin,
14:31obesity and cancer.
14:32I think there's a lot more
14:34we need to learn about obesity,
14:37insulin, and cancer,
14:38and how all of that plays together.
14:40But first we need to take a
14:42short break for a medical minute.
14:44Please stay tuned to learn
14:46more about obesity, insulin,
14:47and cancer with my guest doctor Rachel Perry.
14:51Support for Yale Cancer Answers
14:53comes from AstraZeneca,
14:55a bio pharmaceutical business that
14:57is pushing the boundaries of science
15:00to deliver new cancer medicines.
15:03More information at astrazeneca-us.com.
15:06This is a medical minute about genetic
15:09testing which can be useful for
15:11people with certain types of cancer
15:14that seem to run in their families.
15:16Patients that are considered at risk
15:19receive genetic counseling and testing so
15:21informed medical decisions can be based
15:24on their own personal risk assessment.
15:26Resources for genetic counseling and
15:28testing are available at federally
15:30designated comprehensive cancer centers.
15:32Interdisciplinary teams include geneticists,
15:34genetic counselors, physicians,
15:35and nurses who
15:36work together to provide
15:38risk assessment and steps to
15:40prevent the development of cancer.
15:42More information is available
15:44at yalecancercenter.org.
15:45You're listening to Connecticut public radio.
15:49This is doctor Anees Chagpar
15:51and I'm joined tonight by
15:53my guest doctor Rachel Perry.
15:55We're talking about the role of
15:57obesity and insulin in cancer and
15:59right before the break Rachel, you
16:01were starting to tell us a little
16:04bit about how insulin really works in
16:06terms of causing obesity and how that
16:08plays into the development of cancer.
16:10Can you take us back a couple of
16:13steps and talk about insulin and obesity?
16:16I know insulin is a hormone
16:18it's made by the pancreas,
16:20but how does that cause us to be obese?
16:24And if all of us make insulin,
16:26how come not
16:28all of us are obese?
16:30Those are both important questions,
16:32and honestly, we're still not certain the
16:35metabolic community is still not certain
16:37to what extent insulin causes obesity
16:39versus obesity causing high insulin levels.
16:42We know that obesity causes high
16:44insulin levels because as individuals
16:46become more and more obese,
16:49they become more and more
16:51insulin resistant and that's due to increased
16:53levels of lipid or fat in various tissues.
16:56When we become insulin resistant,
16:58that means we don't respond,
17:00our bodies don't respond very well to
17:03insulin and so our body has to secrete
17:06more insulin to counteract that effect.
17:08Now the question of whether insulin
17:10causes obesity is very interesting
17:13in sort of a chicken and
17:15egg type of question,
17:16and there are a number of
17:19studies that do suggest that
17:21insulin may itself independently cause
17:23obesity and that's at least in large part
17:27because insulin causes fat deposition.
17:29It causes those small molecules
17:31of carbohydrate and fat that are
17:33floating by in our bloodstream to
17:35actually be deposited in tissues in
17:38subcutaneous fat depots and form larger
17:40and larger pieces of fat, and so
17:43in that regard,
17:44it is likely that insulin causes obesity,
17:47at least to some extent.
17:49But as I said, it's more certain
17:52that obesity causes hyperinsulinemia
17:53or high insulin levels because of
17:55that insulin resistance phenomenon.
17:57As you said,
17:58we all need to have insulin.
18:00The body knows if it doesn't
18:03have enough functioning insulin,
18:04because when we don't have enough insulin,
18:07our blood glucose levels get high
18:09without insulin action on various
18:11tissues, wer'e not able to take up
18:13enough glucose or sugar from our
18:16bloodstream into those tissues,
18:17and when that happens,
18:19the body senses the high blood sugar level
18:22and secretes more insulin to try to
18:24counteract the effects of insulin resistance.
18:27So let me get this straight, obesity
18:30causes you to be insulin resistant,
18:33so your body needs to make more insulin.
18:36But that insulin takes sugar from your
18:39bloodstream and deposits it as fat,
18:41which then causes you to be more obese.
18:45So isn't this a vicious cycle?
18:48It absolutely is a vicious cycle and
18:50we and others have shown that if you
18:53intervene in any step of this cycle,
18:56so if you intervene in the step of eating
18:59too many calories, if you intervene
19:01in secreting too much insulin,
19:04if you intervene in depositing that
19:06sugar in tissues as fat if you
19:09intervene in any of these steps,
19:11you can intervene in the cycle
19:13of the development of obesity.
19:15But yes, absolutely,
19:16it's a vicious cycle and this
19:18absolutely contributes to this
19:20pandemic of obesity that we have
19:22in our country and worldwide.
19:24We're
19:25going to get back to exactly how
19:27we can intervene, but let's talk a
19:30little bit about the cancer part.
19:32So we talked a little bit at the
19:35beginning of the show about the fact
19:38that obesity really does drive,
19:40I think it was what 13 different
19:42types of cancer,
19:43but not all cancers are affected by obesity,
19:46but certainly a large number of cancers are.
19:49So how does that happen?
19:51And what does insulin have
19:53to do with it anyways?
19:55Right, so as we were discussing earlier,
19:57I think in reality there are a
20:00number of different factors that
20:01may mediate at least part of this
20:04link between obesity and cancer.
20:06But as you said, we focus on specifically
20:09how insulin may fuel tumor growth.
20:11So, as I mentioned,
20:12individuals with obesity frequently have
20:14high circulating insulin levels because
20:16they tend to be insulin resistant.
20:18And this is indeed a vicious cycle. We
20:20found in a few studies, both in vitro
20:23so in a dish and in vivo, in mice,
20:26that insulin can drive tumor
20:28glucose uptake and metabolism, that
20:30actually was a little bit surprising
20:33initially because conventional wisdom
20:35has said that tumor glucose or sugar
20:37metabolism is constitutively high,
20:39so it would always be high and
20:42not regulated by any hormones,
20:44but the surprising finding that we
20:47and that others have also shown is that in fact,
20:51tumor glucose or sugar
20:52metabolism is insulin dependent,
20:54and so in mice that are obese
20:57and insulin resistant,
20:58they have high circulating insulin
21:00levels and this causes glucose
21:01uptake into their tumor cells.
21:03After the tumor cells take up glucose,
21:06it can be used in two different ways.
21:08It can be used for metabolism,
21:10so simply to provide the fuel that
21:13allows the cells to keep going,
21:15and it can also be used to make
21:18building blocks for cells.
21:19So a unique feature about tumor cells
21:22is that in order to be a tumor,
21:24these cells need to be growing
21:26and dividing all the time.
21:28They grow and divide very rapidly and they
21:31need building blocks to be able to do that,
21:34and glucose is a key fuel to be
21:36able to provide those building
21:38blocks for these tumor cells,
21:40and so in that way glucose
21:42and insulin which drives glucose uptake,
21:44is a key pathogenic factor in tumors.
21:47So let me ask you this,
21:49we know a lot of diabetics who
21:52are type one diabetics who take insulin.
21:55Does that mean that the insulin can actually
21:58be driving tumor growth in these people?
22:01Putting them at increased risk since
22:03their injecting themselves with insulin?
22:05You know that's a key question.
22:07A very important question,
22:09and frankly a personally relevant question, as
22:11I am a person with type one
22:13diabetes and so this is something
22:15that I am very curious about.
22:18The epidemiological evidence doesn't
22:19seem to support a strong role for
22:21exogeneous insulin, that is injected
22:23insulin, in type one diabetic
22:25individuals in driving tumor growth,
22:27and there could be a few
22:29different reasons for that.
22:30It is a little bit surprising,
22:32but what we currently believe
22:34is that you may need two hits.
22:36That is,
22:37high glucose and high insulin levels,
22:39so type one diabetic individuals
22:41who take as much insulin as they
22:43need tend not to have chronically
22:45high glucose levels all the time,
22:47and so it may be that keeping blood
22:49sugar normal is also very important in
22:52these individuals who need to inject
22:54insulin exogeneously to stay alive.
22:56But that's a question that really
22:58is an open question and one
23:00that were very curious about.
23:02It's also entirely possible,
23:03and I think this is likely that
23:06insulin may not be the only factor
23:08that mediates the effects
23:10of obesity on tumor growth,
23:11so it may be that you need high
23:14insulin levels to have an obesity
23:16affect to drive tumor growth,
23:18but that you also need other factors
23:21like inflammatory cytokines or
23:22leptin or other hormones.
23:26And in these lean type one diabetic
23:28individuals they may have high
23:30insulin levels but not these other
23:32factors that may be required
23:34to mediate the effects.
23:37You know, and that makes me
23:39think of something else.
23:40Some people have these benign tumors
23:42in their pancreas that secrete insulin,
23:44so it's kind of a little insulin
23:47factory that they've got going on.
23:49Are those people at increased
23:50risk of developing cancer,
23:52or is it still this,
23:54you need the interplay of a
23:56number of factors so they may
23:58not really be at increased risk.
24:00So I believe that these
24:02folks and I could be wrong on this,
24:04this isn't particularly my field,
24:06but I believe that those folks
24:08are at higher risk of pancreatic,
24:10at least benign tumors of other types,
24:13and maybe at higher risk
24:15of pancreatic cancer,
24:16so that would suggest that insulin
24:18may be acting within the pancreas
24:21as a tumor promoting factor,
24:23but I don't believe they're at
24:25substantially higher risk in other sites.
24:27Now this could be because it's
24:30my understanding that those folks
24:32aren't allowed to go continuously
24:34forever with high insulin levels
24:36secreted by a tumor from the pancreas.
24:38The tumor will be either removed, or
24:41treated,
24:42they may be treated with somatostatin
24:43or some other agent to prevent the
24:46high insulin secretion,
24:48but I would expect that if someone
24:50were chronically having high
24:51insulin levels from continuous
24:53excess secretion of insulin,
24:54that they would in fact be at risk and
24:58that is a study that we've done in mice.
25:01So if you take mice and put a
25:03subcutaneous insulin pellet into
25:05them so that they
25:07chronically have high insulin levels,
25:09they do develop tumors more quickly
25:11and do worse with the tumors
25:13than mice that
25:15don't have too much circulating
25:17insulin all the time.
25:19And when we talked about the fact
25:22that some of the cancers are increased
25:24with obesity and insulin is one
25:27factor that may be playing a role,
25:29sometimes people talk
25:31about this thing called insulin
25:33growth factor or my IGF,
25:34which can be found in some cancers.
25:37Are those related?
25:38So we find that insulin plays more
25:41of role in people who have tumors
25:43that have receptors, for example,
25:45that are more responsive to insulin,
25:47or is this something that is more ubiquitous?
25:50At least in these 13 tumor types,
25:52regardless of whether or not
25:54the tumor secretes insulin or
25:56insulin related growth factor,
25:58there does seem
25:59to be a relationship
26:00between my IGF and insulin,
26:02so that comes in several different ways,
26:05mostly that the IGF1 and insulin
26:07receptors are very similar and both
26:10molecules can activate the other.
26:12So insulin can activate the IG F1 receptor
26:15and IG F1 can activate the insulin receptor
26:18and so I would absolutely expect there to
26:21be interplay between insulin an IG F1,
26:24particularly in those
26:26IGF one expressing tumors.
26:27This also brings up a good
26:29point that I want to highlight,
26:32and that is that the insulin receptor
26:35is not ubiquitously found in tumors.
26:37The tumor types that are associated
26:39with obesity on average have
26:41higher insulin receptor expression,
26:43but that's not 100% across the board,
26:46but because of this cross talk between IGF,1
26:50and insulin that may explain some of
26:53the discrepancies there where a tumor
26:55may be at least weakly obesity associated.
26:58But may not have the insulin receptor
27:00and that may be because the IGF1
27:03receptor compensates for that.
27:04Unfortunately,
27:05tumors are evolved to survive very well,
27:07and so they've sort of developed mechanisms
27:10in their evolution to be able to survive,
27:13and one that I think
27:15is the redundancy of insulin,
27:17and IGF1 action.
27:19In our last few
27:22minutes I really want to get back
27:24to something you said earlier which
27:27was breaking the cycle of obesity.
27:29Can have an impact on reducing cancer risk.
27:32I wanna make sure I got that straight.
27:35So if you're overweight and you
27:37decide to lose weight by cutting
27:40calories or exercise,
27:42that actually can reduce your cancer risk.
27:45Is that right?
27:46Absolutely, epidemiologically,
27:47even losing weight within the last
27:49couple years reduces your cancer risk,
27:51and so it's best
27:54of course, if we're normal weight,
27:56healthy weight throughout our lives.
27:58But it absolutely can have a
28:00huge impact to lower cancer risk.
28:02Losing a little bit of
28:04weight at really anytime.
28:06And you know the other point I want
28:09to highlight is we don't have to be
28:12back to our high school body weight.
28:15This is a case where
28:17Losing 5 to 10% of body weight
28:19if you're an overweight or obese
28:21individual can actually almost fully
28:23normalize your insulin sensitivity,
28:26and so that can be
28:28predicted to almost fully normalize
28:30or reduce the excess risk of obesity,
28:33and so that is something where
28:36that loss of five to 10% is something
28:39that would be much more achievable
28:42then returning to a quote
28:43unquote healthy weight for a lot of
28:46individuals.
28:48Doctor Rachel Perry is an assistant professor in
28:50medicine and Endocrinology
28:51and cellular and Molecular Physiology
28:53at the Yale School of Medicine.
28:56If you have questions,
28:57the address is canceranswers@yale.edu
28:59and past editions of the program
29:01are available in audio and written
29:03form at Yalecancercenter.org.
29:04We hope you'll join us next week to
29:07learn more about the fight against
29:10cancer here on Connecticut public radio.