According to John Hopkins’ Sidney Kimmel Comprehensive Cancer Center, breast cancer rates continue to rise globally suggesting that our attention needs to be put on prevention. While it is difficult to prove causality between even known carcinogens and cancer, avoiding chemicals which have strong ties to this disease is wise. In addition to cigarettes, alcohol, and animal products which are known to increase risk, endocrine disrupting chemicals, EDCs, are increasingly being looked at as suspects. This is due to their now known alterations to the endocrine system and the resulting hormonal disturbances which have been shown to increase risk.
The nervous and endocrine systems regulate all mechanisms in the body. The nervous system consists of the central nervous system, CNS, and the peripheral nervous system, PNS. The CNS consists of the brain and the spinal cord, and the PNS of nerves that connect the CNS to every part of the body. The endocrine system consists of glands that produce hormones which trigger multiple reactions in the body. The glands are the pineal, pituitary, thyroid, thymus, adrenals, pancreas, and ovaries and testes for women and men respectively. Together, the nervous and endocrine systems run the human body. The nervous system provides the information via physical and psychological cues and the endocrine system produces the chemicals that transfers the information to the cells.
The endocrine system distributes hormones along specific pathways: the hypothalamic-pituitary-adrenal (HPA), the hypothalamic-pituitary-gonadal (HPG) axis, the hypothalamic-pituitary-growth hormone (GH) axis, and the hypothalamic-pituitary-thyroid (HPT) axis. The hypothalamus is the ruler of the endocrine system. (Nicholas, 2015)
On the HPA axis, the hypothalamus produces a hormone called corticotropin-releasing factor (CRF). CRF travels to the anterior pituitary gland, binds to specific receptors on cells which produce adrenocorticotropic hormone, ACTH, which travels to the adrenal glands, which produce glucocorticoids. Glucocorticoids are then returned to the hypothalamus and the pituitary glands decreasing CRF and ACTH release. Glucocorticoids influence metabolism, the cardiovascular system, bone and calcium metabolism, the CNS, growth, development, reproduction, and immunity. It has been shown that alcohol affects the HPA. (Nicholas, 2015)
On the HPG axis, the hypothalamus produces luteinizing hormone releasing hormone, LHRH, which travels to the pituitary, attaches to specific receptors and triggers the production of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). LH is responsible for the production of healthy male hormones. FSH ensures normal development of gonadal hormones in males and females; these include testosterone in men, and estrogen and progesterone in the female. These hormones then return to hypothalamic-pituitary unit and encourage or discourage further release of LHRH, LH, and FSH. Healthy balance of these hormones are paramount for reproductive health, nutrient metabolism, healthy cardiovascular system, bone growth and development, central nervous system, and immunity. Alcohol has been shown to affect the HPG axis, raise estrogen levels, and suppress progesterone. (Nicholas, 2015)
Along the GH axis, the hypothalamus produces growth hormone releasing factor (GRF), travels to the anterior pituitary, binds to GRF receptors, and enhances GH production. Via the same pathway, the hormone somatostatin inhibits GH secretion. GH travels to the liver which produces insulin-like growth factor 1 (IGF-1). IGF-1 carries out the functions of GH such as protein formation and cell growth at the tissue level. It then feeds back to the hypothalamus and the pituitary reducing GH synthesis and secretion. Alcohol has also been shown to alter the GH axis and disturb levels of GH. (Nicholas, 2015)
The HPT axis is paramount to all mammals as all metabolic processes of each cell proper levels of thyroid hormone. The hypothalamus produces thyrotropin releasing hormone (TRH). It travels to the anterior pituitary gland which produces thyroid-stimulating hormone (TSH), which produces thyroxine (T4) and triiodothyronine (T3). Alcohol also affect the HPT axis. (Nicholas, 2015)
In addition to alcohol, epidemiological data also shows hormonal changes associated with EDCs and an increase in cancers. An endocrine-disrupting substance changes the hormonal and homeostatic balance in the body. Two of the most important aspects of these disruptions are related to xenoestrogens, compounds which mimic estrogens, and disruption of thyroid function. Endocrine disruptors include industrial solvents/lubricants, plastics, pesticides, pharmaceutical agents, and heavy metals. Xenoestrogens include phytoestrogen isoflavonoids, polychlorinated biphenyls or PCBs found in chlorine, plastics components, surfactants used in cleaning detergents, UV filters, preservatives, pesticides, and pollutants produced by incomplete combustion. These chemicals are also known to disrupt thyroid hormones. However, while these pathways increase human exposure, humans are most likely to encounter them through their food. (DeCoster, 2012)
The 2009 Endocrine Society Scientific statement lists considerable evidence indicating that endocrine disruptors contribute to the risk of breast cancer. Estrogen causes cells to proliferate and promotes growth of any existing tumor, and many EDCs are estrogenic. In addition, studies such as The Agricultural Health study in Iowa and North Carolina showed that Farmers and commercial pesticide applicators have a significantly increased risk of prostate cancer. Participants in this study showed high blood serum levels of herbicides, pesticides, insecticides, although this risk was more significant in those with genetic predisposition. It is well known that these chemicals break down into estrogenic chemicals making this a risk for men also. (DeCoster, 2012)
Determining which endocrine disruptors promote breast cancer is difficult to do. But doing so is important since recently it has been shown that exposure by fetuses to such certain chemical affect breast cancer risk. A new study published in Hormones & Cancer, a journal of the Endocrine Society, indicates that adult women who were exposed prenatally to BPA or DES could be at increased risk of breast cancer.
“BPA is a weak estrogen and DES is a strong estrogen, yet our study shows both have a profound effect on gene expression in the mammary gland (breast) throughout life,” said Hugh Taylor, MD, of the Yale University School of Medicine in New Haven, Conn. and lead author of the study. “All estrogens, even ‘weak’ ones can alter the development of the breast and ultimately place adult women who were exposed to them prenatally at risk of breast cancer.” (Anonymous, 2010)
Economic interests have a major role in shaping what we know and don’t know about endocrine disruptors. Huge resources are invested in research to understand how birth control, hormone replacement therapy (HRT), and breast cancer treatment and prevention affects the risk of cancer. However, consumer products such as detergents and baby bottles are never tested for how they break down and how they affect the endocrine system. For example, dioxins which are endocrine disrupting chemicals and known carcinogens, are a byproduct of industrial processes such as bleaching paper pulp or pesticide manufacture. They can be directly ingested via meats, dairy, water, or breast milk. Indirect exposure can come from bleached coffee filters, bleached tampons, and the ground since dioxins do not break down. (DeCoster, 2012)
Millions of dollars are spent on producing pesticides and on bleaching paper products, but nothing is being spent on studying the long term effects of using bleached tampons and cervical cancer risk for example. The Environmental Defense Fund states that toxicological information is available for only 29 percent of the 3,000 most used chemicals in the United States, with fewer having been tested for effects on endocrine alterations or breast cancer. (Brody,2015) The lack of safety testing is likely due not only to the expense of testing the products, but also to a lowering of profits which would result from discovering that these chemicals are indeed detrimental to our health.
To reduce the risk of cancer, maintain a healthy weight, exercise, limit alcohol intake, and conduct breast exams (but consider alternative methods since x-rays are also known to damage DNA which increases risk). Another risk factor is HRT. Clinical trials conducted in the 1990s show that HRT increases breast cancer risk without reducing heart disease. It was also seen that with lesser HRT use, breast cancer incidence has dropped. (www.hopkinsmedicine.org) In addition, since EDCs have been shown so often to cause hormonal disruptions, and hormones such as estrogen have such a strong indication of increased risk, lowering exposure to EDCs would further reduce the risk.
It seems that the more we learn about cancer, the less we know about it. We still don’t ultimately know why even in a family with strong history of cancer, some people develop the disease while others don’t. We know what increases risks, but don’t know why it is only triggered in some. We are therefore were we have always been, where there is only one thing to do: live as well as possible and hope for the best. Luckily, we now have more knowledge and therefore the added power of at least opting out of dangerous practices, should we chose to do so.
Anonymous. Breast cancer; Pre-natal exposure to endocrine disrupting chemicals linked to
breast cancer. NewsRx Health. (June, 2010) Retrieved from www.evergaldeslibrary.com
on 2/16/2015. Document URL: http://search.proquest.com.ezp-02.lirn.net /docview
Brody, J., Ruddel R., Melly, R., Maxwell, N. Endocrine disruptors and breast cancer. Forum
for Applied Research and public Policy. (1998) Retrieved on 2/16/2015 from
www.evergladeslibrary.com. Document URL: http://search.proquest.com.ezp-02.lirn.net
De Coster, S., Larebeke, N. Endocrine disrupting chemicals: Associated Disorders and
Mechanisms of Action. Journal of Environmental and Public Health (2012). Retrieved
from www.evergladeslibrary.com on 2/15/2015. Document URL:
John Hopkins Staff. Prevention. The Johns Hopkins University, The Johns Hopkins Hospital,
and Johns Hopkins Health System. Retrieved from http://www.hopkinsmedicine.org/
Nicholas, E., Emanuele, M. The endocrine system. Alcohol Health and Research World (1997).
Retrieved from www.evergladeslibrary.com on 2/12/2015. Document URL