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Why cancer does not occur in myogenic heart cells? Is there any special ability in heart cells to resist cancer ?

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    $\begingroup$ Could you provide a reference to the article that you read that in? I want to look at what was said before answering. $\endgroup$ Aug 21, 2015 at 16:09
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    $\begingroup$ @Pi5 just to let you know, the answer you marked as correct is, in fact, not. You can see my comment below it for more info. $\endgroup$
    – MattDMo
    Aug 22, 2015 at 2:12
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    $\begingroup$ What do you mean by "myogenic heart cells" precisely? As I understand it, "myogenic" refers to a precursor cell (myoblast, myotube etc), as opposed to a fully developed cardiomyocyte. Such myogenic cells are mainly present during early development --- are you thinking of a childhood cancer of the heart? $\endgroup$
    – Roland
    Sep 22, 2015 at 6:12
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    $\begingroup$ Related question: biology.stackexchange.com/questions/10809/… $\endgroup$
    – Roland
    Sep 22, 2015 at 6:20
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    $\begingroup$ @user19679 Absolutely no problem. Anyway I'll write a short answer even if I think the question is unclear. $\endgroup$
    – Roland
    Dec 21, 2015 at 16:45

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As a preface, this isn't a comprehensive answer for everything. As MattDMo points out, some of the original answer was poor in it's presentation. In my update there's some supporting information to some expert testimonial, but this is mainly targeted at adult cases rather than pediatric cases, i.e. why would cardiac cancer be rare in an adult with no prior history of cancer. There's a reference #5 at the bottom which goes into some of the genetic conditions that result in rhabdomyocarcoma.

Cardiac muscle cells do not divide particularly often (though they may divide: Evidence for cardiomyocyte renewal in humans). This would be a good mechanism of resistance of heart tissue to a more typical or rapid cancer development, compared to say, the endothelium of a vessel or an interstitial/connective tissue cell. Not to say heart tumors are impossible, either, as rhabdomyocarcoma is a good example of a cardiac tumor. Moreover, here's an excerpt from this article on heart cancer:

“There’s not a lot of fatty tissue [in the heart],” Gaynor said. Even more, “the heart’s enclosed in a membrane,” he explained. Known as the pericardium, this fluid-filled sac may itself become engulfed by cancer, with tumors metastasizing to the outside of it, but still it does its job of protecting our precious hearts.

So, even though cancer can happen anywhere there are cells, your heart remains virtually immune due to its muscular nature and the assistance of the pericardium. Smart heart.

And then from Cancer Prognosis: Role of BMI and Fat Tissue,

Many prospective clinical trials have linked excess body weight—typically represented as a BMI of 25kg/m2 of body surface area or greater—with a higher risk of development of cancers, including postmenopausal breast cancer in women and esophageal, colon, pancreatic, endometrial, and kidney cancers in both sexes. The number of obese Americans will increase by an estimated 65 million by 2030, increasing cancer diagnoses by 500,000 (Lancet 2011;378:815–25).

So fat content has it's role in progressing cancers, determinately. Let's explore this part. The adipocyte isn't simply a storage for fat, it has it's own host of proteins it produces and secretes. In obesity, the adipose tissue becomes dysregulated in it's secretion of adipokines [1]. The book Adipose Tissue and Cancer by M. Kolonin, the author notes that two major adipokines, leptin and adiponectin, play a major role in tumorigenesis by induction of cell survival and proliferation pathways [2]. Also duly noted, increased circulating insulin and insulin-like growth factors due to insulin resistance results in mitogenic effects on tumor cells.

White adipose tissue has been shown by Pedro et al. to increase bioavailability of sex hormones such as estradiol, through increased aromatase activity and "increased insulin and bioactive IGF-1 levels which downregulate the concentration of the circulating sex hormone-binding globulin, resulting in an increased fraction of bioavailable estradiol, but decreased testosterone production." The same study has a section on inflammation induced by adipose tissue in section 3.2, the entire article is rather long but they sum up some of the information into a figure,

enter image description here

Source: Pedro et al.

Generally speaking, and in reference to the expert testimonial above from Dr. Gaynor, the heart isn't a very fatty organ, and it's protected from the surrounding adipose tissue by the pericardium. You could also argue that the fast flow of blood through the heart would leave a smaller fraction of circulating tumorigenic molecules for ready uptake by cardiac cells.

Being said, and while I haven't any data for the molecular pathogenesis for cardiac tumors, nondividing epidermal cells have been shown to enter a proliferative state in response to inflammation [3]. We also see that adipokines have been implicated in heart disease due to pro-inflammatory effects [4]. My concession here is that the rarity of cancers in adult cardiac muscle cells is because this process is very slow, and it's aided in part by the sort of environment the heart finds itself in. We often see cases of cardiac tumors in children due to errors in development [5].

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    $\begingroup$ Yeah the first part is a good point, cardiac cancers are rare but they do occur. And lack of replication may play a big role in this. I would point out though that there are plenty of nervous system cancers that affect cells that do not divide much if at all either (so we do have to be careful about assigning causation with division rate) $\endgroup$ Aug 21, 2015 at 18:35
  • $\begingroup$ That was my exact thought as well. I did want to make the distinction, though, that for the cardiac muscle cells themselves primary tumors are quite rare; More so than those of endothelial cells or interstitial cells that are part of the heart, and progress into cancer of the heart, like an angiosarcoma. $\endgroup$
    – CKM
    Aug 21, 2015 at 20:54
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    $\begingroup$ This doesn't really answer the question. Your second sentence is incorrect - cells do not have to be dividing to accumulate mutations. You then go on to say that this is your "opinion", which does not by any means constitute proof. The BMI part is irrelevant to the question - it's been well-established that excess weight can lead to all sorts of health risks, including cardiovascular disease and cancer of various body parts, but it has nothing to do with heart cancer. Please answer the question factually and support your reasoning with relevant citations from the scientific literature. $\endgroup$
    – MattDMo
    Aug 22, 2015 at 2:11
  • $\begingroup$ It looked good at the time, but I've tried to make something more acceptable in the little time I had. $\endgroup$
    – CKM
    Aug 22, 2015 at 21:07

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