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  #1   ^
Old Thu, Jan-01-09, 19:42
Nancy LC's Avatar
Nancy LC Nancy LC is offline
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Default High insulin levels linked with enhanced breast cancer risk

Full Article from Dr. Briffa.

Quote:
Yesterday saw the on-line publication of a study which, again, suggests that insulin may be a provoking factor in breast cancer [1]. The study compared insulin levels in more than 800 women with breast cancer, and a similar number without the disease. Women with the highest insulin levels were found to be at a 46 per cent increased risk of breast cancer. However, the associated between insulin levels and increased risk of breast cancer was only found to be significant in women who did not use hormone replacement therapy.


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  #2   ^
Old Thu, Jan-01-09, 19:47
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LessLiz LessLiz is offline
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Wait, insulin levels *after* breast cancer are not the same as insulin measures before breast cancer.
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  #3   ^
Old Thu, Jan-01-09, 20:05
Nancy LC's Avatar
Nancy LC Nancy LC is offline
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Quote:
Originally Posted by LessLiz
Wait, insulin levels *after* breast cancer are not the same as insulin measures before breast cancer.

Huh? Not sure I understand.
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  #4   ^
Old Thu, Jan-01-09, 20:19
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LessLiz LessLiz is offline
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Default

Read what you quoted. They were looking at women with breast cancer and women without it, not even *vaguely* like looking at women without breast cancer and testing to see if the ones with high insulin levels are more likely to develop breast cancer.

It is pretty well known that cancers drive all sorts of hormonal changes, including changes in insulin levels. It is not at all useful to look at women with breast cancer and try to say that some hormonal level adds to the risk since those levels may well exist as a result of the disease.
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  #5   ^
Old Fri, Feb-06-09, 10:30
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Nancy LC Nancy LC is offline
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Default High insulin levels increased breast cancer risk in postmenopausal women

http://www.endocrinetoday.com/view.aspx?rid=36782
Quote:
Postmenopausal women with hyperinsulinemia were at least two times more likely to develop breast cancer compared with women with the lowest insulin levels. Interventions that target insulin and its signaling pathways may decrease breast cancer risk in these women.

Researchers with the multiyear WHI followed health outcomes in 93,676 postmenopausal women. In 2004, they selected a subset of more than 1,600 women without diabetes: 835 had incident breast cancer. They assessed fasting insulin levels, naturally occurring estradiol levels and BMI.

There was a positive association between insulin levels and risk for breast cancer (HR=1.46; 95% CI, 1.00-2.13 for the highest vs. lowest quartile of insulin level). Most of this effect was observed in the large subset of women from the WHI study who did not receive hormone therapy.

However, the association with insulin level varied by HT use. After controlling for multiple breast cancer risk factors, insulin levels were associated with breast cancer only among women who did not receive HT (HR=2.40; 95% CI, 1.30-4.41 for the highest vs. lowest quartile of insulin level). There was an association between obesity and risk for breast cancer among women who did not receive HT (HR=2.12; 95% CI, 1.26-3.58). However, this association was attenuated by adjustment for insulin.

J Natl Cancer Inst. 2009;101:48-60.
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  #6   ^
Old Fri, Feb-06-09, 11:01
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KarenJ KarenJ is offline
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Default

I thought I read somewhere that insulin was a precursor to the hormones that feed hormonally fed cancers? Is this correct?

Quote:
There was an association between obesity and risk for breast cancer among women who did not receive HT (HR=2.12; 95% CI, 1.26-3.58). However, this association was attenuated by adjustment for insulin.


Mumbler! I didn't understand a single word of that. What is wrong with me?
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  #7   ^
Old Fri, Feb-06-09, 11:07
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Nancy LC Nancy LC is offline
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I'm assuming that HT means Hormone Treatment? So what I'd normally call HRT.

But the rest of it goes straight over my head.
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  #8   ^
Old Fri, Feb-06-09, 12:28
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melibsmile melibsmile is offline
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Quote:
Originally Posted by KarenJ
Mumbler! I didn't understand a single word of that. What is wrong with me?



Quote:
There was an association between obesity and risk for breast cancer among women who did not receive HT (HR=2.12; 95% CI, 1.26-3.58). However, this association was attenuated by adjustment for insulin.


HR is the hazard ratio, which means that they were using a Cox Proportional Hazards model in their data analysis. Women who were obese had about two times the hazard of getting breast cancer. The 95% confidence interval does not include 1 (the null value), meaning that the association is statistically significant. The attenuation by insulin means that when they included the effect of insulin in the model, the association of obesity to breast cancer hazard was smaller. This means that insulin confounds the relationship between obesity and breast cancer, as it is associated with both of them.

Does that help or make it worse?

--Melissa
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  #9   ^
Old Fri, Feb-06-09, 14:07
Nancy LC's Avatar
Nancy LC Nancy LC is offline
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Default

Melissa, that helps. So let me translate back what I think you said:

1) More breast cancer is seen in obese women
2) Insulin is higher in many obese women and some thin women
3) Breast cancer is more common with women with high insulin rather than just obesity.

Do ya suppose anyone will make the leap that it's the insulin causing the obesity AND the cancer?
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  #10   ^
Old Fri, Feb-06-09, 15:17
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melibsmile melibsmile is offline
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Default

Quote:
Originally Posted by Nancy LC
Melissa, that helps. So let me translate back what I think you said:

1) More breast cancer is seen in obese women
2) Insulin is higher in many obese women and some thin women
3) Breast cancer is more common with women with high insulin rather than just obesity.

Do ya suppose anyone will make the leap that it's the insulin causing the obesity AND the cancer?


Yes, you got it. This insulin relationship to both obesity and breast cancer is the definition of a confounding factor--an additional variable in a statistical model that correlates (positively or negatively) with both the dependent variable (breast cancer) and the independent variable (obesity).

I would hope that this would prompt additional research on the relationship between insulin and breast cancer, but I'm not going to hold my breath.

--Melissa
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  #11   ^
Old Fri, Feb-06-09, 15:19
Nancy LC's Avatar
Nancy LC Nancy LC is offline
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Is there a way to get your insulin level measured? And what would be the most meaningful way to measure it? Fasting insulin levels or post-meal?
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  #12   ^
Old Fri, Feb-06-09, 15:22
melibsmile's Avatar
melibsmile melibsmile is offline
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Default

Quote:
Originally Posted by Nancy LC
Is there a way to get your insulin level measured? And what would be the most meaningful way to measure it? Fasting insulin levels or post-meal?


There is. Dr Eades talked about it in PPLP. It's not commonly done since it's a lot cheaper and easier to measure glucose rather than insulin. I think when they do measure insulin they will measure both--measure fasting levels and then take multiple measurements over the course of a few hours after eating a glucose "meal" to track the rise and then fall of insulin levels in response.

--Melissa
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  #13   ^
Old Fri, Feb-06-09, 16:50
LC FP LC FP is offline
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Default

I frequently order fasting insulin levels along with fasting blood sugars for my patients. It's not an expensive test. And I've never had an insurance company deny it. And I think it's helpful information, sort of a staging test--

For example, a normal FBS and a low insulin level (< 10) means you're insulin-sensitive. A normal FBS and a high insulin level mean's you're insulin resistant. An elevated FBS and a high insulin level mean's you're verging on type-2 diabetes, and a high FBS with a low insulin level means you're a burned-out type 2, or a type 1.
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  #14   ^
Old Fri, Feb-06-09, 17:06
Nancy LC's Avatar
Nancy LC Nancy LC is offline
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Default

I don't necessarily think blood glucose can tell you what your insulin is doing, right? you could have high glucose and high insulin (hyperinsulinism) or high glucose and low insulin (beta cells gettings burned out).

I'm going to try to get a fasting insulin blood test done. I am getting high BG's in the morning and I can't quite figure out why. I'm not diabetic, at least not on my current diet, but I do see some outrageous BG numbers if I eat a really horribly carby meal. But my BG right before I eat dinner is usually 80-90, which seems really nice.
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  #15   ^
Old Sat, Feb-07-09, 15:42
LC FP LC FP is offline
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Nancy, your liver is probably pretty insulin resistant if your FBS is high. Basal insulin production overnight should stop your liver from making glucose, but apparently your liver is resistant and continues to make glucose. There's no other reason BS should be high so long after you've eaten. During the day your pancreas responds appropriately or super-appropriately to ingested food and produces excess insulin to drive your BS down before dinner. Incretin hormones like GLP-1 can help you produce excess insulin.

I'd bet if you had a 2 hour glucose tolerance test with insulin levels your fasting insulin level would be relatively low, maybe in the 10-15 range, but at 2 hours it could be quite high like 50-100 depending how long you've been dealing with insulin resistance.
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